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The working principle of springmvc is: 1. The browser sends a request to DispatcherServlet; 2. Find the corresponding Controller according to the request; 3. Return to ModelAndView; 4. Find the corresponding view object View and render it; 5. Return to browser.
SpringMVC working principle:
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1. The specified request sent by the browser will be handed over to DispatcherServlet, which will entrust other modules to perform real business and data processing;
2. DispatcherServlet will find HandleMapping, find the corresponding Controller according to the browser's request, and The request is handed over to the target Controller;
3. After the target Controller completes the business, it returns a ModelAndView to the DispatcherServlet;
4. The DispatcherServlet finds the corresponding view object View through the ViewResolver view parser;
4. The view object View is responsible for rendering and returning to the browser.
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Let’s take a look at the code example:
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name>springmvc</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <!-- spring入口 --> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <!-- 项目启动时,就加载并实例化 --> <load-on-startup>1</load-on-startup> </servlet> <!-- 拦截所有不包括jsp的请求 --> <servlet-mapping> <servlet-name>springmvc</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> </web-app>
springmvc-servlet.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <!-- springmvc注解驱动 --> <mvc:annotation-driven></mvc:annotation-driven> <!-- 开启注解扫描 --> <context:component-scan base-package="cn.itcast.controller"></context:component-scan> <!-- 配置试图解析器 prefix:指定试图所在目录 suffix:指定视图的后缀名 例如:prifex="/WEB-INF/jsp/",suffix=".jsp",当viewname="test"时,跳转到/WEB-INF/jsp/test.jsp页面 --> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/jsp/"></property> <property name="suffix" value=".jsp"></property> </bean> </beans>
UserControll class
@Controller @RequestMapping("user") public class UserController { @RequestMapping("findAllUsers") public ModelAndView findAllUsers() { ModelAndView mv = new ModelAndView(); ArrayList<User> users = new ArrayList<User>(); for (int i = 0; i < 5; i++) { User user = new User(); user.setUsername("zs" + i); user.setAge(20 + i); user.setIncome(16000.0+i*100); user.setIsMarry(false); user.setHobby(new String[] { "篮球"+i, "足球"+i }); users.add(user); } mv.addObject("users", users); mv.setViewName("users"); return mv; } }
Entity class
public class User implements Serializable { /** * */ private static final long serialVersionUID = 1L; private String username; private Integer age; private Boolean isMarry; private Double income; private String[] hobby; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public Boolean getIsMarry() { return isMarry; } public void setIsMarry(Boolean isMarry) { this.isMarry = isMarry; } public Double getIncome() { return income; } public void setIncome(Double income) { this.income = income; } public String[] getHobby() { return hobby; } public void setHobby(String[] hobby) { this.hobby = hobby; } @Override public String toString() { return "User [username=" + username + ", age=" + age + ", isMarry=" + isMarry + ", income=" + income + ", hobby=" + Arrays.toString(hobby) + "]"; } }
jsp page
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> <link rel="stylesheet" type="text/css" href="/css/user.css" /> </head> <body> <table id="customers"> <tr> <th>用户名</th> <th>年龄</th> <th>收入</th> <th>婚姻状态</th> <th>兴趣爱好</th> </tr> <!-- 遍历后台传递的集合数据 --> <c:forEach items="${users}" var="user"> <tr> <td>${user.username}</td> <td>${user.age}</td> <td>${user.income}</td> <!-- 判婚姻状态 --> <td><c:choose> <c:when test="${user.isMarry}">已婚</c:when> <c:otherwise>未婚</c:otherwise> </c:choose> </td> <td> <!-- 再次遍历用户爱好 --> <c:forEach items="${user.hobby}" var="hobby" varStatus="status"> ${hobby} <!-- 如果不是最后一个爱好,则加上逗号,否则就不加 --> <c:if test="${!status.last}">,</c:if> </c:forEach> </td> </tr> </c:forEach> </table> </body> </html>
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