SpringMVC （八）SpringMVC返回值类型

SpringMVC的返回值类型有MedelAndView，String，void,Object数值型，集合类型等等

前两种我们之前写案例的时候一直在用，现在看一下返回值是void

第一种：返回viod

返回值是void的话，就要结合ajax来写

准备一个用户类

package demo09Return;

/**
 * Created by mycom on 2018/3/26.
 */
public class UserInfo {
    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

和控制器类

package demo09Return;

import com.alibaba.fastjson.JSON;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by mycom on 2018/3/26.
 */
@Controller
public class ReturnController {

    @RequestMapping("/one")
    public void doFirst(HttpServletResponse response) throws IOException {
        List<UserInfo> list=new ArrayList<UserInfo>();
        UserInfo user=new UserInfo();
        user.setUsername("敖");
        user.setPassword("1225");
        list.add(user);
        String data = JSON.toJSONString(list);
        response.getWriter().write(data);

    }
}

在页面上

<%--
  Created by IntelliJ IDEA.
  User: mycom
  Date: 2018/3/26
  Time: 17:13
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.8.3.min(1).js"></script>
<script type="text/javascript">
    $(function () {
        $("input").click(function () {
            $.ajax({
                url:"/one",
                type:"POST",
                success:function (data) {
                    $.each(eval("("+data+")"),function (i,dom) {
                        alert(dom.username);
                    })
                }
            })
        })
    })
</script>
<head>
    <title>Title</title>
</head>
<body>
<input type="button" value="按钮">
</body>
</html>

在配置文件中

<?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:mvc="http://www.springframework.org/schema/mvc"
       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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="demo09Return"></context:component-scan>

    <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>


</beans>

注意不要忘记修改web.xml中的classpath的值

 第二种：返回Object

引入jar

<!--返回Object类型的jar-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.8.1</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.5.1</version>
        </dependency>
 //返回int
    @RequestMapping("/first")
    @ResponseBody
    public Object doFirst(){
        return 1;
    }

    //返回String
    @RequestMapping(value = "/second",produces = "text/html;charset=UTF-8")
    @ResponseBody
    public Object doSecond(){
        return "明天会更好";
    }

    //返回对象
    @RequestMapping(value = "/third")
    @ResponseBody
    public Object doThird(){
        UserInfo user=new UserInfo();
        user.setUsername("增");
        user.setPassword("123456");
        return user;
    }

    //返回集合
    @RequestMapping(value = "/four")
    @ResponseBody
    public Object doFour(String name){
        List<UserInfo> list=new ArrayList<UserInfo>();
        UserInfo user=new UserInfo();
        user.setUsername("敖");
        user.setPassword("1225");
        UserInfo user2=new UserInfo();
        user2.setUsername(name);
        user2.setPassword("123456");
        list.add(user);
        list.add(user2);
        String data = JSON.toJSONString(list);
       return list;
    }


    //返回map
    @RequestMapping(value = "/five")
    @ResponseBody
    public Object doFive(){
        Map<String,UserInfo> map=new HashMap<String, UserInfo>();
        UserInfo user=new UserInfo();
        user.setUsername("敖");
        user.setPassword("1225");
        UserInfo user2=new UserInfo();
        user2.setUsername("增");
        user2.setPassword("123456");
        map.put(user.getUsername(),user);
        map.put(user2.getUsername(),user2);
        return map;
    }

配置文件中：

<?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:mvc="http://www.springframework.org/schema/mvc"
       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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="demo09Return"></context:component-scan>

    <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    <!--注解驱动-->
    <mvc:annotation-driven/>


</beans>

测试页面：

<%--
  Created by IntelliJ IDEA.
  User: mycom
  Date: 2018/3/26
  Time: 17:13
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.8.3.min(1).js"></script>
<script type="text/javascript">
    /*$(function () {
        $("input").click(function () {
            $.ajax({
                url:"/four",
                type:"POST",
                success:function (data) {
                    $.each(function (i,dom) {
                        alert(dom.username);
                    })
                }
            })
        })
    })*/

    $(function () {
        $("input").click(function () {
            $.ajax({
                url:"/five",
                type:"POST",
                success:function (data) {
                    $.each(function (i,dom) {
                        alert(dom.username);
                    })
                }
            })
        })
    })
</script>
<head>
    <title>Title</title>
</head>
<body>
<input type="button" value="按钮">
</body>
</html>
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原文地址：https://www.cnblogs.com/my-123/p/8654603.html