집 >데이터 베이스 >MySQL 튜토리얼 >mybatis-的使用(使用配置文件)
简介: MyBatis 是支持普通 SQL 查询,存储过程和高级映射的优秀持久层框架。 MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以及结果集的检索。MyBatis 使用简单的 XML或注解用于配置和原始映射,将接口和 Java 的 POJOs(Plan Old Java Objects,普
简介: MyBatis 是支持普通 SQL 查询,存储过程和高级映射的优秀持久层框架。 MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以及结果集的检索。MyBatis 使用简单的 XML或注解用于配置和原始映射,将接口和 Java 的 POJOs(Plan Old Java Objects,普通的 Java对象)映射成数据库中的记录。<code class="language-xml"><?xml version="1.0" encoding="UTF-8" ?><code class="language-xml"><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"<code class="language-xml">"http://mybatis.org/dtd/mybatis-3-config.dtd"><code class="language-xml"><configuration><code class="language-xml"> <code class="language-xml"><!-- 这个是po类的设置 这样不必在sql中写po类的全限定名 --> <code class="language-xml"> <typeAliases> <typeAlias alias="Photo" type="com.bjsxt.po.Photo"/> </typeAliases> <code class="language-xml"> <code class="language-xml"> <environments default="development"><code class="language-xml"> <environment id="development"><code class="language-xml"> <transactionManager type="JDBC" /><code class="language-xml"> <dataSource type="POOLED"><code class="language-xml"> <property name="driver" value="com.mysql.jdbc.Driver" /><code class="language-xml"> <property name="url" value="jdbc:mysql://localhost/photo" /><code class="language-xml"> <property name="username" value="root" /><code class="language-xml"> <property name="password" value="xiaohang" /><code class="language-xml"> </dataSource><code class="language-xml"> </environment><code class="language-xml"> </environments><code class="language-xml"> <mappers><code class="language-xml"> <!-- sql 映射文件 这个是对应的配置文件 这个配置文件和dao里面的接口类联系 --><code class="language-xml"> <mapper resource="com/smallang/dao/PhotoDao.xml" /><code class="language-xml"> </mappers><code class="language-xml"></configuration></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">3、接着,创建dao和对应xml sql映射文件:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><strong>@、</strong> 创建一个接口,里面就是一个或多个方法:比如像这样:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">(这个里面就是各种方法,sql语句是放在映射的xml文件里面的,当然这个参数和返回类型是会面)
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">public interface PhotoDao {<code class="language-xml"> public void savePhoto(Photo photo);<code class="language-xml"> public Photo getPhotoById(int id); <code class="language-xml"> public Photo findPhotoByName(String name,int uid); <code class="language-xml">// public Photo findPhotoByName2(Map<String, Object> v); <code class="language-xml"> public Photo findPhotoByName2(Photo photo); <code class="language-xml"> public List<Photo> findPhotos();<code class="language-xml">} </code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><strong>@、</strong> 创建于类名相同的xml,像这样PhotoDao.xml 里面的配置是这样的:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><?xml version="1.0" encoding="UTF-8" ?><code class="language-xml"><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"<code class="language-xml">"http://mybatis.org/dtd/mybatis-3-mapper.dtd"><code class="language-xml"><mapper namespace="com.bjsxt.dao.PhotoDao"><code class="language-xml"> <!-- Id :dao中的方法名字 parameterType:方法中传参的类型 --><code class="language-xml"> <insert id="savePhoto" parameterType="Photo"> <!-- name 代表方法中第一个参数的name属性值 --><code class="language-xml"> insert into t_photo (name,uploadDate) values (#{name},#{uploadDate})<code class="language-xml"> </insert><code class="language-xml"> <!-- java中基本数据类型和string 都不需指定类型 parameterType="int" 不要--><code class="language-xml"> <select id="getPhotoById" resultType="Photo"> <!-- dsfsfs 代表方法中第一个参数的值 --><code class="language-xml"> select * from t_photo where id=#{dsfsfs}<code class="language-xml"> </select><code class="language-xml"> <code class="language-xml"> <!-- #{和方法中参数的名字无关} {表示第n个参数的值或者其属性的值,或者其key的值}--><code class="language-xml"> <select id="findPhotoByName" resultType="Photo"> <!-- {}可以使用下标表示n --><code class="language-xml"> select * from t_photo where name=#{0} and uid=#{1}<code class="language-xml"> </select> <code class="language-xml"> <code class="language-xml"> <select id="findPhotoByName2" resultType="Photo"> <!-- {}: map中的key --><code class="language-xml"> select * from t_photo where name=#{name} and uid=#{uid}<code class="language-xml"> </select><code class="language-xml"> <code class="language-xml"> <!-- resultType表示sql语句执行之后返回的数据类型 --><code class="language-xml"> <select id="findPhotos" resultType="Photo"><code class="language-xml"> select * from t_photo<code class="language-xml"> </select><code class="language-xml"></mapper></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">(解释上面的东东: 绿色:id= 对应的方法名;
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">蓝色:parameterType 参数的类型 特殊类必学写
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">黄色:sql 的 语句 (里面的#{参数类属性名} 或 #{0,1.。。}下标 来使用参数的数据)
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">粉色:resultType = 返回类型 )
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">然后这里有一个多表查询,返回list<map>d 数据;像这样 </map>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><select id="findPhotoName" resultType="map"><code class="language-xml"> select p.name as pn,a.name as an from t_photo as p join t_album a on p.aid=a.id<code class="language-xml"> </select><code class="language-xml">public List<Photo> findPhotos();</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">还有<strong>高级的动态SQL(DynamicSQL)的使用</strong>,也是在这个,xml里面: 这些的东东; 例子: <u><em>Foreach的:</em></u> foreach元素的属性主要有item,index,collection,open,separator,close。item表示集合中每一个元素进行迭代时的别名,index指定一个名字,用于表示在迭代过程中,每次迭代到的位置,open表示该语句以什么开始,separator表示在每次进行迭代之间以什么符号作为分隔符,close表示以什么结束,在使用foreach的时候最关键的也是最容易出错的就是collection属性,该属性是必须指定的,但是在不同情况下,该属性的值是不一样的,主要有一下3种情况:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">如果传入的是单参数且参数类型是一个List的时候,collection属性值为list
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">如果传入的是单参数且参数类型是一个array数组的时候,collection的属性值为array
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">如果传入的参数是多个的时候,我们就需要把它们封装成一个Map了,当然单参数也可以封装成map,实际上如果你在传入参数的时候,在MyBatis里面也是会把它封装成一个Map的,map的key就是参数名,所以这个时候collection属性值就是传入的List或array对象在自己封装的map里面的key
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">public List<Album> findAlbum(List<Integer> ids); <code class="language-xml">//list<?> 接口里面的 因为查找包含条件不同,所以需要动态 <code class="language-xml"> <select id="findAlbum" resultType="Album"><code class="language-xml"> select * from t_album where id in <code class="language-xml"> <foreach collection="list" item="id" open="(" close=")" separator=","><code class="language-xml"> #{id}<code class="language-xml"> </foreach> <code class="language-xml"> </select></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">If 的例子就不用了; where的例子有一个:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"> <select id="findAlbum2" resultType="Album"><!-- 整数不能当成int,而是Integer --><code class="language-xml"> select * from t_album <code class="language-xml"> <where><code class="language-xml"> <if test="name!=null"><code class="language-xml"> name=#{name} <code class="language-xml"> </if><code class="language-xml"> <if test="name !=null and uid!=null"><code class="language-xml"> and <code class="language-xml"> </if><code class="language-xml"> <if test="uid!=null"><code class="language-xml"> uid=#{uid}<code class="language-xml"> </if><code class="language-xml"> </where><code class="language-xml"> </select><code class="language-xml">就是如果where 后面有东东的话 就会输出where + 后面的东东 否则 就不输出</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">choose choose元素的作用就相当于JAVA中的switch语句,基本上跟JSTL中的choose的作用和用法是一样的,通常都是与when和otherwise搭配的。看如下一个例子:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"> <select id="dynamicChooseTest" parameterType="Blog" resultType="Blog"><code class="language-xml"> select * from t_blog where 1 = 1 <code class="language-xml"> <choose><code class="language-xml"> <when test="title != null"><code class="language-xml"> and title = #{title}<code class="language-xml"> </when><code class="language-xml"> <when test="content != null"><code class="language-xml"> and content = #{content}<code class="language-xml"> </when><code class="language-xml"> <otherwise><code class="language-xml"> and owner = "owner1"<code class="language-xml"> </otherwise><code class="language-xml"> </choose><code class="language-xml"> </select></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">trim: trim元素的主要功能是可以在自己包含的内容前加上某些前缀,也可以在其后加上某些后缀,与之对应的属性是prefix和suffix;可以把包含内容的首部某些内容覆盖,即忽略,也可以把尾部的某些内容覆盖,对应的属性是prefixOverrides和suffixOverrides;正因为trim有这样的功能,所以我们也可以非常简单的利用trim来代替where元素的功能,示例代码如下:
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"> <select id="dynamicTrimTest" parameterType="Blog" resultType="Blog"><code class="language-xml"> select * from t_blog <code class="language-xml"> <trim prefix="where" prefixOverrides="and |or"><code class="language-xml"> <if test="title != null"><code class="language-xml"> title = #{title}<code class="language-xml"> </if><code class="language-xml"> <if test="content != null"><code class="language-xml"> and content = #{content}<code class="language-xml"> </if><code class="language-xml"> <if test="owner != null"><code class="language-xml"> or owner = #{owner}<code class="language-xml"> </if><code class="language-xml"> </trim><code class="language-xml"> </select></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
<code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml"><code class="language-xml">set: set元素主要是用在更新操作的时候,它的主要功能和where元素其实是差不多的,主要是在包含的语句前输出一个set,然后如果包含的语句是以逗号结束的话将会把该逗号忽略,如果set包含的内容为空的话则会出错。有了set元素我们就可以动态的更新那些修改了的字段。(如果set中一个条件都不满足,即set中包含的内容为空的时候就会报错。)<br>
这个的例子不copy了,感觉没什么用的;
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