0025SpringMVC的几种响应方式

本文主要涉及到一下几种响应方式：

1、返回字符串
2、返回void
3、返回ModelAndView
4、转发关键字forward和重定向关键字redirect返回字符串
5、ajax调用返回json

具体实现参看代码：

responseTest.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/7
  Time: 8:41
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    
    
    


    testString

    testVoid

    testModelAndView

    testForwardOrRedirect

    发送ajax请求

ResponseController.java

package com.example.controller;

import com.example.bean.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Controller
@RequestMapping("/response")
public class ResponseController {
    public static final String SUCCESS = "success";
    /*1、返回字符串*/
    /*2、返回void*/
    /*3、返回ModelAndView*/
    /*4、转发关键字forward和重定向关键字redirect返回字符串*/
    /*5、ajax调用返回json*/
　　/*返回字符串和返回ModelAndView会经视图解析器解析，返回void和使用关键字的形式不会经视图解析器解析*/

    /*1、返回字符串*/
    /*这种方式会经过视图解析器解析，拼接上前缀和后缀*/
    @RequestMapping("/testString")
    public String testString(Model model){
        User user = new User();
        user.setName("张三");
        user.setAge(18);
        model.addAttribute("user",user);
        System.out.println("测试返回字符串");
        return SUCCESS;
    }

    /*2、返回void*/
    @RequestMapping("testVoid")
    public void testVoid(HttpServletRequest request, HttpServletResponse response){
        System.out.println("测试返回void，可利用转发或重定向，或者直接写输出给用户");
        //转发,不会经过视图解析器解析，但是由于是服务器内跳转，不用写项目名称，但是需要写转发的完整路径
        /*try {
            request.getRequestDispatcher("/WEB-INF/pages/success.jsp").forward(request,response);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }*/
        //重定向,由于是客户端重新发送请求，所以需要带项目名，且不能直接访问WEB-INF下的内容
        //所以此处以访问webapp下的index.jsp页面为例，地址栏的地址会发生变化
        /*try {
            response.sendRedirect(request.getContextPath() + "/index.jsp");
        } catch (IOException e) {
            e.printStackTrace();
        }*/
        //直接写给客户端，即写出的内容会以新的页面的形式显示
        //为了防止中文乱码，需用一下代码设置相关编码
        try {
            response.setCharacterEncoding("UTF-8");
            response.setContentType("text/html;charset=UTF-8");
            response.getWriter().print("您好");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /*3、返回ModelAndView*/
    //底层也会把对象存入request作用域中，设置视图名称时可直接写字符串，会调用到视图解析器解析
    @RequestMapping("testModelAndView")
    public ModelAndView testModelAndView(){
        System.out.println("测试返回ModelAndView");
        User user = new User();
        user.setName("张三");
        user.setAge(18);
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject(user);
        modelAndView.setViewName(SUCCESS);
        return modelAndView;
    }
    /*4、转发关键字forward和重定向关键字redirect返回字符串*/
    //这种方式不会用到视图解析器，需要自己将视图路径写正确
    @RequestMapping("testForwardOrRedirect")
    public String testForwardOrRedirect(){
        System.out.println("测试testForwardOrRedirect");
        //测试forward
        /*return "forward:/WEB-INF/pages/success.jsp";*/
        //测试redirect，此处与调用response.sendRedirect()方法有区别，可不加项目名
        return "redirect:/index.jsp";
    }
    /*5、ajax调用返回json*/
    /*a、js文件夹下引入jquery.min.js文件，并在responseTest.jsp中引入该文件
    * b、经测试引入的js文件不生效，原因为被前端控制器拦截了，
    *   解决办法在springmvc.xml中配置哪些静态资源不被拦截，如：
    * c、responseTest。jsp中的方法能正常调用后，将方法改为ajax异步方法
    * d、ResponseController中编写请求对应的方法，如果用@RequestBody接收，需要参数类型是字符串，
    *   若想用User类型接收json格式的字符串，且方法返回User类型数据，页面以json格式接收，需引入相关jar包*/
    @RequestMapping("/testAjax")
    public @ResponseBody User testAjax(@RequestBody User user){
        System.out.println("测试testAjax");
        System.out.println(user);
        user.setName("李四");
        user.setAge(50);
        return user;
    }

}

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/12/4
  Time: 14:07
  To change this template use File | Settings | File Templates.
--%>
<%--为了使el表达式生效，需要在此写上isELIgnored="false"--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>


    


    
入门成功
    <%--如下两行仅用于测试@SessionAttributes注解时使用--%>
    <%--${ requestScope.get("msg") }

    ${ sessionScope.get("msg") }--%>
    <%--返回ModelAndView测试--%>
    用户名为：${user.name}

    密码为：${user.age}

springmvc.xml

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:c="http://www.springframework.org/schema/c"
       xmlns:cache="http://www.springframework.org/schema/cache"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:jdbc="http://www.springframework.org/schema/jdbc"
       xmlns:jee="http://www.springframework.org/schema/jee"
       xmlns:lang="http://www.springframework.org/schema/lang"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.3.xsd
      http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
      http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
      http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
      http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd
      http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.3.xsd
      http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-4.3.xsd
      http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.3.xsd
      http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-4.3.xsd
      http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd ">
    
    
    
    
        
        
        
        
    
    
    
        
            
                
            
        
    

    
    　　
    

    
    
    

pom.xml

  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.0.0

  com.example
  springmvc_day01_01_start
  1.0-SNAPSHOT
  war

  springmvc_day01_01_start Maven Webapp
  
  http://www.example.com

  
    UTF-8
    1.7
    1.7
    5.0.2.RELEASE
  

  
    
    
    
      org.springframework
      spring-aop
      ${spring.version}
    

    
    
      org.springframework
      spring-aspects
      ${spring.version}
    
    
    
      org.springframework
      spring-beans
      ${spring.version}
    
    
    
      org.springframework
      spring-context
      ${spring.version}
    
    
    
      org.springframework
      spring-core
      ${spring.version}
    
    
    
      org.springframework
      spring-expression
      ${spring.version}
    
    
    
      org.springframework
      spring-orm
      ${spring.version}
    
    
    
      org.springframework
      spring-jdbc
      ${spring.version}
    
    
    
      org.springframework
      spring-test
      ${spring.version}
    
    
    
      org.springframework
      spring-tx
      ${spring.version}
    
    
    
      org.springframework
      spring-web
      ${spring.version}
    
    
    
      org.springframework
      spring-webmvc
      ${spring.version}
    
    

    
    
      org.springframework.boot
      spring-boot-devtools
    
    
    
      com.fasterxml.jackson.core
      jackson-databind
      2.9.0
    
    
      com.fasterxml.jackson.core
      jackson-core
      2.9.0
    
    
      com.fasterxml.jackson.core
      jackson-annotations
      2.9.0
    


  

  
    springmvc_day01_01_start
    
      
        
          maven-clean-plugin
          3.1.0
        
        
        
          maven-resources-plugin
          3.0.2
        
        
          maven-compiler-plugin
          3.8.0
        
        
          maven-surefire-plugin
          2.22.1
        
        
          maven-war-plugin
          3.2.2
        
        
          maven-install-plugin
          2.5.2
        
        
          maven-deploy-plugin
          2.8.2
        
      
    
  

 

若有理解不到之处，望指正！