这一篇讲以下三个知识点：
1.@RequestMapping——请求映射注解
2.@RequestParam——请求参数
3.ModelAndView——返回模型和视图
4.SpringMVC——属性自动封装
5.SpringMVC——POST请求乱码解决
6.Controller——内部转发与重定向
示例：（学生信息的查询、添加、修改，删除）——为了方便就不链接数据库直接在类中模拟了一些数据
1.配置springMVC的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_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>SpringMVC2display-name>
<welcome-file-list>
<welcome-file>index.jspwelcome-file>
welcome-file-list>
<servlet>
<servlet-name>springmvcservlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
<init-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:spring-mvc.xmlparam-value>
init-param>
servlet>
<servlet-mapping>
<servlet-name>springmvcservlet-name>
<url-pattern>*.dourl-pattern>
servlet-mapping>
<filter>
<filter-name>characterEncodingFilterfilter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilterfilter-class>
<init-param>
<param-name>encodingparam-name>
<param-value>utf-8param-value>
init-param>
filter>
<filter-mapping>
<filter-name>characterEncodingFilterfilter-name>
<url-pattern>*.dourl-pattern>
filter-mapping>
web-app>
2.配置spring-mvc.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:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.maya"/>
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/jsp/" />
<property name="suffix" value=".jsp">property>
bean>
beans>
3.建立model层，实体类student
package com.maya.model; public class Student { private int id; private String name; private int age; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public Student(int id, String name, int age) { super(); this.id = id; this.name = name; this.age = age; } //空参构造函数一定要加上，不然再SpringMVC进行自动封装时会报init<>异常 public Student() { super(); } }
4.建立controller层，StudentController类
package com.maya.controller; import java.util.ArrayList; import java.util.List; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.servlet.ModelAndView;//是web.servlet.ModelAndView!!!不要选错 import com.maya.model.Student; @Controller//声明这是控制层 @RequestMapping("/student")//为了区分模块，在请求时通常会在模块前加一个前缀 public class StrudentController { private static ListstudentList=new ArrayList (); static{//模拟数据 studentList.add(new Student(1, "张三", 11)); studentList.add(new Student(2, "李四", 12)); studentList.add(new Student(3, "王五", 13)); } @RequestMapping("/list")//定义请求的名字 public ModelAndView list(){//ModelAndView返回模型和视图 ModelAndView mav=new ModelAndView(); mav.addObject("studentList", studentList); mav.setViewName("student/list");//设置视图的名，student文件名下的list.jsp return mav; } @RequestMapping("/preSave") //required默认是true！ 与value同时出现 public ModelAndView preSave(@RequestParam(value="id",required=false) String id){ //接收前台参数id，因为添加修改都用这一个请求，那么required应设为false，后面定义接收参数的类型 ModelAndView mav=new ModelAndView(); if(id==null){//如果没有接收到参数，说明是添加 mav.setViewName("student/add");//设置视图的名，student文件名下的add.jsp }else{//否则就是修改了 mav.addObject("student", studentList.get(Integer.parseInt(id)-1)); mav.setViewName("student/update");//设置视图的名，student文件名下的update.jsp } return mav; } @RequestMapping("/saveOrUdate") public String save(Student student){//进行添加或者修改 if(student.getId()!=0){//根据id判断 Student s=studentList.get(student.getId()-1); s.setName(student.getName()); s.setAge(student.getAge()); }else{ studentList.add(student); } return "redirect:/student/list.do";//重定向 } @RequestMapping("/delete") public String delete(@RequestParam("id") int id){//这样就可以将String id强制转换成int id了 studentList.remove(id-1); //return "redirect:/student/list.do";//当然除了重定向之外，还有转发(如下) return "forward:/student/list.do"; } }
5.建立view视图层，因为设定了在jsp文件夹下的student文件下！所以要相应的建立正确的路径
<%@ 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>list.jsptitle> head> <body> <a href="${pageContext.request.contextPath }/student/preSave.do">添加a> <table> <tr> <th>编号th> <th>姓名th> <th>年龄th> <th>操作th> tr> <c:forEach var="list" items="${studentList }"> <tr> <td>${list.id }td> <td>${list.name }td> <td>${list.age }td> <td><a href="${pageContext.request.contextPath }/student/preSave.do?id=${list.id }">修改a>td> <td><a href="delete.do?id=${list.id }">删除a>td> tr> c:forEach> table> body> html>
<body> 添加 <form action="${pageContext.request.contextPath}/student/saveOrUdate.do" method="post"> 姓名：<input type="text" name="name" /> 年龄：<input type="text" name="age" /> <input type="submit" value="提交" /> form> body>
<body> 修改 <form action="${pageContext.request.contextPath }/student/saveOrUdate.do" method="post"> 姓名：<input type="text" name="name" value="${student.name }" /> 年龄：<input type="text" name="age" value="${student.age }" /> <input type="hidden" name="id" value="${student.id }" /> <input type="submit" value="提交" /> form> body>