实现图书的增删查改（CRUD）

图书的MySQL数据库创建脚本： CREATE TABLE books ( id int NOT NULL AUTO_INCREMENT, title varchar(255) NOT NULL, description text, image_url varchar(255), price decimal(8, 2) NOT NULL, author varchar(255) NOT NULL, isbn varchar(255) NOT NULL,

图书的MySQL数据库创建脚本：

CREATE TABLE books (
  id int NOT NULL AUTO_INCREMENT,
  title varchar(255) NOT NULL,
  description text,
  image_url varchar(255),
  price decimal(8, 2) NOT NULL,
  author varchar(255) NOT NULL,
  isbn varchar(255) NOT NULL,
  publisher varchar(255) NOT NULL,
  user_id int NOT NULL,
  PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

图书实体类文件Book.java主要代码：

public class Book {
    private Long id;
    private String title;
    private String description;
    private String image_url;
    private double price;
    private String author;
    private String isbn;
    private String publisher;
    private User user;
    ...
}

在User类中添加集合变量books：

public class User {
    ...
    private Set<book> books = new HashSet<book>();
    ...
}
</book></book>

在User.hbm.xml中配置和图书的一对多关联：

<!-- Bidirectional one-to-many association to Book -->
<set name="books" inverse="true">
    <key column="user_id" not-null="true"></key>
    <one-to-many class="name.dohkoos.book.model.Book"></one-to-many>
</set>

图书的表映射文件Book.hbm.xml代码：

<hibernate-mapping>
    <class name="name.dohkoos.book.model.Book" table="books">
        <id name="id">
            <generator class="increment"></generator>
        </id>
        <property name="title" not-null="true"></property>
        <property name="description"></property>
        <property name="image_url"></property>
        <property name="price" not-null="true"></property>
        <property name="author" not-null="true"></property>
        <property name="isbn" not-null="true"></property>
        <property name="publisher" not-null="true"></property>
        <many-to-one name="user" column="user_id" not-null="true"></many-to-one>
    </class>
</hibernate-mapping>

BookService.java中的代码相对简单，因为没什么复杂的业务逻辑，只是负责把Action和Dao这两层连接起来。

BookDao.java中的代码主要实现图书的读取，更新和删除：

package name.dohkoos.book.dao;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import name.dohkoos.book.model.Book;
public class BookDao {
    private SessionFactory sessionFactory;
    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }
    public List<book> getBookList() {
        Session session = sessionFactory.openSession();
        try {
            Query query = session.createQuery("from Book b");
            List<book> bookList = query.list();
            return bookList;
        } finally {
            session.close();
        }
    }
    public Book getBook(Long bookId) {
        Session session = sessionFactory.openSession();
        try {
            Query query = session.createQuery("from Book b where b.id = :id");
            query.setLong("id", bookId);
            query.setMaxResults(1);
            return (Book)query.uniqueResult();
        } finally {
            session.close();
        }
    }
    public void saveOrUpdateBook(Book book) {
        Session session = sessionFactory.openSession();
        Transaction ts = null;
        try {
            ts = session.beginTransaction();
            session.saveOrUpdate(book);
            ts.commit();
        } finally {
            session.close();
        }
    }
    public void deleteBook(Long bookId) {
        Session session = sessionFactory.openSession();
        Transaction ts = null;
        try {
            ts = session.beginTransaction();
            Book book = (Book)session.get(Book.class, bookId);
            session.delete(book);
            ts.commit();
        } finally {
            session.close();
        }
    }
}
</book></book>

BookAction.java负责协调图书应用程序间的运转。接收访问请求，与模型进行交互，将合适的视图展示给用户：

package name.dohkoos.book.action;
import java.util.List;
import name.dohkoos.account.model.User;
import name.dohkoos.book.model.Book;
import name.dohkoos.book.service.BookService;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class BookAction extends ActionSupport {
    private static final long serialVersionUID = 2538923417705852774L;
    private Long bookId;
    private Book book;
    private List<book> bookList;
    private BookService bookService;
    public String list() throws Exception {
        bookList = bookService.getBookList();
        return "list";
    }
    public String show() throws Exception {
        book = bookService.getBook(bookId);
        return "show";
    }
    public String input() throws Exception {
        if (bookId != null) {
            book = bookService.getBook(bookId);
        }
        return INPUT;
    }
    public String saveOrUpdate() throws Exception {
        User user = (User)ActionContext.getContext().getSession().get("user");
        book.setUser(user);
        bookService.saveOrUpdateBook(book);
        return SUCCESS;
    }
    public String delete() throws Exception {
        bookService.deleteBook(bookId);
        return SUCCESS;
    }
    ...
}
</book>

在applicationContext.xml中添加Book的相关配置，如下面代码所示：

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    ...
    <property name="mappingResources">
        <list>
            ...
            <value>name/dohkoos/book/model/Book.hbm.xml</value>
        </list>
    </property>
</bean>
...
<!-- book -->
<bean id="bookDao" class="name.dohkoos.book.dao.BookDao">
    <property name="sessionFactory" ref="sessionFactory"></property>
</bean>
<bean id="bookService" class="name.dohkoos.book.service.BookService">
    <property name="bookDao" ref="bookDao"></property>
</bean>
<bean id="bookAction" class="name.dohkoos.book.action.BookAction" scope="prototype">
    <property name="bookService" ref="bookService"></property>
</bean>

在Struts 2配置文件struts.xml中include文件book.xml。以下是book.xml文件的内容：

<?xml version="1.0" encoding="UTF-8"?>

<struts>
    <package name="book" extends="struts-default">
        <action name="*Book" method="{1}" class="bookAction">
            <result name="list">/books/list.jsp</result>
            <result name="show">/books/show.jsp</result>
            <result name="input">/books/form.jsp</result>
            <result type="redirectAction">listBook</result>
        </action>
    </package>
</struts>

视图文件show.jsp作为显示单本图书的信息，代码很简单，就不放出来了，只把list.jsp和form.jsp的代码列出来。

list.jsp用来显示所有的图书：

<h1>Listing books</h1>

Title	Description	Image url	Price	Author	ISBN	Publisher	Action
							Show Edit Destroy

Add

当用户新建或者更新图书时，视图form.jsp就上场了。因为被两个逻辑使用，显示的标题等信息也不相同，所以需要判断图书的id是否存在，如果不存在的话即是新建业务，否则就是更新操作。

<if test="book.id != null">
    <h1>Editing book</h1>
</if>
<else>
    <h1>Add book</h1>
</else>
<form action="saveOrUpdateBook" method="post">
    <div class="field">
        <hidden name="book.id" value="%{book.id}"></hidden>
    </div>
    <div class="field">
        <textfield name="book.title" label="Title"></textfield>
    </div>
    <div class="field">
        <textarea name="book.description" label="Description" rows="5" cols="25"></textarea>
    </div>
    <div class="field">
        <textfield name="book.image_url" label="Image URL"></textfield>
    </div>
    <div class="field">
        <textfield name="book.price" label="Price"></textfield>
    </div>
    <div class="field">
        <textfield name="book.author" label="Author"></textfield>
    </div>
    <div class="field">
        <textfield name="book.isbn" label="ISBN"></textfield>
    </div>
    <div class="field">
        <textfield name="book.publisher" label="Publisher"></textfield>
    </div>
    <div class="actions">
        <if test="book.id != null">
        <submit value="Update"></submit>
        </if>
        <else>
        <submit value="Save"></submit>
        </else>
  </div>
</form>
<if test="book.id != null">
<a href="http://codemany.com/" showbook.action>Show</a> |
</if>
<a action="listBook">Back</a>

最后还要完成图书模型的服务端校验。Struts 2的校验文件有两种格式：ActionName-validation.xml和ActionName-alias-validation.xml。第一种会对该Action中的每个方法进行校验，不符合只对saveOrUpdate校验的要求。在BookAction.java同目录下创建BookAction-saveOrUpdateBook-validation.xml文件：

<validators>
    <field name="book">
        <field-validator type="visitor">
            <param name="appendPrefix">true
            <message></message>
        </field-validator>
    </field>
</validators>

当然，还要在Book.java所在的位置创建Book-validation.xml文件：

<validators>
    <field name="title">
        <field-validator type="required">
            <message>Price is required</message>
        </field-validator>
    </field>
    ...
    <field name="price">
        <field-validator type="required">
            <message>Price is required</message>
        </field-validator>
        <field-validator type="double">
            <param name="minInclusive">0.01
            <message>Price should be at least 0.01</message>
        </field-validator>
    </field>
</validators>

看着BookAction-saveOrUpdateBook-validation.xml这么长的文件名是不是有点无语:)没关系，BookAction-validation.xml配置文件还是可以用的，只要在BookAction.java中那些不需要进行校验的方法上添加@SkipValidation；也可以在action配置中启用validation.excludeMethods参数：

<action name="*Book" method="{1}" class="bookAction">
    <interceptor-ref name="defaultStack">
        <param name="validation.excludeMethods">list,show,input,delete
    </interceptor-ref>
    ...
</action>

代码下载：https://github.com/dohkoos/JBookShelf

原文地址：实现图书的增删查改（CRUD）, 感谢原作者分享。