Spring MVC的Controller接受请求方式以及编写请求处理方法

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Controller接受请求参数的常见方法：

1、通过Bean接受请求参数：

创建POJO实体类

创建pojo包，并在该包中创建实体类UserForm，代码：

package pojo;

public class UserForm {

    private String uname;//与请求参数名称相同

    private String upass;

    private String reupass;

    public String getUname() {

        return uname;

    }

    public void setUname(String uname) {

        this.uname = uname;

    }

    public String getUpass() {

        return upass;

    }

    public void setUpass(String upass) {

        this.upass = upass;

    }

    public String getReupass() {

        return reupass;

    }

    public void setReupass(String reupass) {

        this.reupass = reupass;

    }

}

创建控制器类，在controller包中创建控制器类IndexController和UserController

其中@RequestMapping注解的作用个人浅显的理解就是将方法或类注解为一个“路径”的名称，以便在HTML，JSP（视图）向控制器发送请求时寻找到。

IndexController代码：

package controller;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

@Controller//在这里@Controller相当于@Controller（“indexController”）

@RequestMapping("/index")

public class IndexController {

    @RequestMapping("/login")

    public String login() {

        return "login";//跳转到“/WEB-INF/jsp/login.jsp”

    }

    @RequestMapping("/register")

    public String register() {

        return "register";

    }

}

UserController代码：

package controller;

import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import org.springframework.ui.Model;

import org.springframework.web.bind.annotation.ModelAttribute;

import org.springframework.web.bind.annotation.RequestMapping;

import pojo.UserForm;

import service.UserService;

@Controller//在这里@Controller相当于@Controller（“userController”）

@RequestMapping("/user")

public class UserController {

    //得到一个用来记录日志的对象，这样打印信息的时候能够标记打印的是那个类的信息

    private static final Log logger = LogFactory.getLog(UserController.class);

    //将服务依赖注入到属性userService

    @Autowired

     public UserService userService;

    /**

     * 处理登录

     */

    @RequestMapping("/login")

    public String login(UserForm user, HttpSession session, Model model) {

        if(userService.login(user)){

            session.setAttribute("u", user);

            logger.info("成功");

            return "main";//登录成功，跳转到main.jsp

        }else{

            logger.info("失败");

            model.addAttribute("messageError", "用户名或密码错误");

            return "login";

        }

    }

    /**

     *处理注册

     */

    @RequestMapping("/register")

    public String register(@ModelAttribute("user") UserForm user) {

        if(userService.register(user)){

            logger.info("成功");

            return "login";//注册成功，跳转到login.jsp

        }else{

            logger.info("失败");

            //使用@ModelAttribute("user")与model.addAttribute("user", user)功能相同

          //在register.jsp页面上可以使用EL表达式${user.uname}取出ModelAttribute的uname值

            return "register";//返回register.jsp

        }

    }

}

创建页面视图，结合视图中更能理解 @RequestMapping注解的作用，其中关于本次知识的核心代码为<body>标签中的内容:

创建register.jsp代码：

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<!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">

<style type="text/css">

    .textSize{

        width: 100pt;

        height: 15pt

    }

</style>

<title>注册画面</title>

<script type="text/javascript">

    //注册时检查输入项

    function allIsNull(){

        var name=document.registForm.uname.value;

        var pwd=document.registForm.upass.value;

        var repwd=document.registForm.reupass.value;

        if(name==""){

            alert("请输入姓名！");

            document.registForm.uname.focus();

            return false;

        }

        if(pwd==""){

            alert("请输入密码！");

            document.registForm.upass.focus();

            return false;

        }

        if(repwd==""){

            alert("请输入确认密码！");

            document.registForm.reupass.focus();

            return false;

        }

        if(pwd!=repwd){

            alert("2次密码不一致，请重新输入！");

            document.registForm.upass.value="";

            document.registForm.reupass.value="";

            document.registForm.upass.focus();

            return false;

        }

        document.registForm.submit();

        return true;

    }

</script>

</head>

<body>

    <form action="${pageContext.request.contextPath }/user/register" method="post" name="registForm">

        <table

        border=1

        bgcolor="lightblue"

        align="center">

            <tr>

                <td>姓名：</td>

                <td>

                    <input class="textSize" type="text" name="uname" value="${user.uname }"/>

                </td>

            </tr>

            <tr>

                <td>密码：</td>

                <td><input class="textSize" type="password" maxlength="20" name="upass"/></td>

            </tr>

            <tr>

                <td>确认密码：</td>

                <td><input class="textSize" type="password" maxlength="20" name="reupass"/></td>

            </tr>

            <tr>

                <td colspan="2" align="center"><input type="button" value="注册" onclick="allIsNull()"/></td>

            </tr>

        </table>

    </form>

</body>

</html>

创建login.jsp代码：

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<!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>后台登录</title>

    <style type="text/css">

    table{

        text-align: center;

    }

    .textSize{

        width: 120px;

        height: 25px;

    }

    * {

        margin: 0px;

        padding: 0px;

    }

    body {

        font-family: Arial, Helvetica, sans-serif;

        font-size: 12px;

        margin: 10px 10px auto;

        background-image: url(${pageContext.request.contextPath }/images/bb.jpg);

    }

    </style>

    <script type="text/javascript">

    //确定按钮

    function gogo(){

        document.forms[0].submit();

    }

    //取消按钮

    function cancel(){

        document.forms[0].action = "";

    }

    </script>

  </head>

  <body>

      <form action="${pageContext.request.contextPath }/user/login" method="post">

    <table>

        <tr>

            <td colspan="2"><img src="${pageContext.request.contextPath }/images/login.gif"></td>

        </tr>

        <tr>

            <td>姓名：</td>

            <td><input type="text" name="uname" class="textSize"></td>

        </tr>

        <tr>

            <td>密码：</td>

            <td><input type="password" name="upass" class="textSize"></td>

        </tr>

        <tr>

            <td colspan="2">

                <input type="image" src="${pageContext.request.contextPath }/images/ok.gif" onclick="gogo()" >

                <input type="image" src="${pageContext.request.contextPath }/images/cancel.gif" onclick="cancel()" >

            </td>

        </tr>

    </table>

    ${messageError }

    </form>

  </body>

</html>

2、通过处理方法的形参接收请求参数

即将控制类UserConttroller中的register方法的代码修改如下：

@RequestMapping("/register")

/**

*通过形参的计收请求参数，形参名称与请求参数名称完全相同

*/

    public String register(String uname，String upass，Model model) {

        if(userService.equals(uname)&&userService.equals(upass)){

            logger.info("成功");

            return "login";//注册成功，跳转到login.jsp

        }else{

            logger.info("失败");

            return "register";//返回register.jsp

        }

    }

3、通过HttpServetRequest接受请求参数（推荐使用）：

即将控制类UserConttroller中的register方法的代码修改如下：

    @RequestMapping("/register")

    public String register(HttpServletRequest request，Model model) {

               String uname = request.getParameter("uname");

               String upass = request.getParameter("upass");

        if(userService.equals(uname)&&userService.equals(upass)){

            logger.info("成功");

            return "login";//注册成功，跳转到login.jsp

        }else{

            logger.info("失败");

            return "register";//返回register.jsp

        }

    }

其他@PathVariable、@RequestParam等不多赘述，原理相同。