SpringMVC:响应数据和结果视图

一、返回值分类

　　1.字符串

　　2.void

　　

　　3.ModelAndView

二、转发和重定向

　　1.forward转发

   

　　

      

　 2.Redirect重定向

三、ResponseBody响应json数据

需要在pom.xml中添加如下代码：

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

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>cn.itcast</groupId>
  <artifactId>ssm</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>ssm Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <spring.version>5.0.2.RELEASE</spring.version>
    <slf4j.version>1.6.6</slf4j.version>
    <log4j.version>1.2.12</log4j.version>
    <mysql.version>5.1.6</mysql.version>
    <mybatis.version>3.4.5</mybatis.version>
  </properties>

  <dependencies>
    <!-- spring -->
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>1.6.8</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>compile</scope>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>${mysql.version}</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <!-- log start -->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>${log4j.version}</version>
    </dependency>

    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>${slf4j.version}</version>
    </dependency>

    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>${slf4j.version}</version>
    </dependency>

    <!-- log end -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>${mybatis.version}</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>1.3.0</version>
    </dependency>
    <!-- jakson-START-->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.9.0</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.9.0</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>2.9.0</version>
    </dependency>
    <!-- jakson-END-->
    <dependency>
      <groupId>c3p0</groupId>
      <artifactId>c3p0</artifactId>
      <version>0.9.1.2</version>
      <type>jar</type>
      <scope>compile</scope>
    </dependency>
  </dependencies>

  <build>
    <finalName>ssm</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.0.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.7.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.20.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

完整代码：

jsp代码：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
   String path=request.getContextPath();
%>
<html>
<head>
    <title>重定向</title>
    <script src="js/jquery.min.js"></script>
    <script>
        // 页面加载，绑定单击事件
        $(function(){
            $("#btn").click(function(){
                alert("hello btn");
                // 发送ajax请求
                $.ajax({
                    // 编写json格式，设置属性和值
                    url:"user/testAjax",
                    contentType:"application/json;charset=UTF-8",
                    data:'{"username":"hehe","password":"123","age":30}',
                    dataType:"json",
                    type:"post",
                    success:function(data){
                        // data服务器端响应的json的数据，进行解析
                        alert(data);
                        alert(data.username);
                        alert(data.password);
                        alert(data.age);
                    }
                });
            });
        });
    </script>
</head>
<body>
<a href="<%=path%>/user/testReturnString">testReturnString</a>
<br>
<a href="<%=path%>/user/testReturnVoid">testReturnVoid</a>
<br>
<a href="<%=path%>/user/testModelAndView">testModelAndView</a>
<br>
<a href="<%=path%>/user/testForwardOrRedirect">testForwardOrRedirect</a>
<br>
<input type="button" value="发送ajax的请求" id="btn">
</body>
</html>

控制层

package cn.itcast.controller;
import cn.itcast.domain.User;
import org.springframework.stereotype.Controller;
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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Controller("jsonController")
@RequestMapping("/user")
public class UserController {
    @RequestMapping("/testReturnString")
    public String testReturnString(){
        System.out.println("testReturnString方法执行了............");
        return  "success";
    }
    @RequestMapping("testReturnVoid")
    public void testReturnVoid(
            HttpServletRequest request,
                               HttpServletResponse response) throws Exception{
        System.out.println("testVoid方法执行了...");
        // 编写请求转发的程序
        /* request.getRequestDispatcher("/WEB-INF/pages/success.jsp")
           .forward(request,response);*/
        // 重定向:这种方式相当于重新定向到webapp下的根目录下去寻找.
         //response.sendRedirect(request.getContextPath()+"/index.jsp");
        // 设置中文乱码
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        // 直接会进行响应
        response.getWriter().print("你好");
        return;
    }
    /**
     * 使用关键字的方式进行转发或者重定向
     * @return
     */
    @RequestMapping("/testForwardOrRedirect")
    public String testForwardOrRedirect(){
        System.out.println("testForwardOrRedirect方法执行了...");
        // 请求的转发
        // return "forward:/WEB-INF/pages/success.jsp";
        // 重定向
        return "redirect:/index.jsp";
    }
    /*
    * 返回ModeAndView
    * @return
    * */
    @RequestMapping("/testModelAndView")
    public ModelAndView testModelAndView(){
        System.out.println("testModelAndView方法执行了...");
        // 创建ModelAndView对象
        ModelAndView mv = new ModelAndView();
        // 模拟从数据库中查询出User对象
        User user = new User();
        user.setUsername("小凤");
        user.setPassword("456");
        user.setAge(30);
        // 把user对象存储到mv对象中，也会把user对象存入到request对象
        mv.addObject("user",user);
        // 跳转到哪个页面
        mv.setViewName("success");
        return  mv;
    }

    /**
     * 模拟异步请求响应
     */
    @RequestMapping("/testAjax")
    public @ResponseBody User testAjax(@RequestBody User user){
        System.out.println("testAjax方法执行了...");
        // 客户端发送ajax的请求，传的是json字符串，后端把json字符串封装到user对象中
        System.out.println(user);
        // 做响应，模拟查询数据库
        user.setUsername("haha");
        user.setAge(40);
        // 做响应
        return user;
    }

}