spring mvc 返回json数据的四种方式

一.返回ModelAndView,其中包含map集

/*
     * 返回ModelAndView类型的结果
     * 检查用户名的合法性,如果用户已经存在，返回false，否则返回true(返回json数据，格式为{"valid",true})
     */
    @RequestMapping(value = "/checkNameExistsMethod2", produces = "application/json;charset=UTF-8") //这里的produces值在不设置的情况下将根据返回结果自动决定
    public @ResponseBody
    ModelAndView checkNameValidMethod2(@RequestParam String name) {
        boolean result = true;
       //...
        Map<String, Boolean> map = new HashMap<>();
        map.put("valid", result);
        return new ModelAndView(new MappingJackson2JsonView(), map);
    }

 

 

二.返回String类型的json，这里有两种方式。

方式一：使用jackson-databind-x.x.x.jar包中的ObjectMapper将Map型数据改写为String并返回

  /*
     * 返回String类型的结果
     * 检查用户名的合法性,如果用户已经存在，返回false，否则返回true(返回json数据，格式为{"valid",true})
     */
    @RequestMapping(value = "/checkNameExistsMethod1", produces = "application/json;charset=UTF-8")
    public @ResponseBody
    String checkNameValidMethod1(@RequestParam String name) {
        boolean result = true;
        //...
        Map<String, Boolean> map = new HashMap<>();
        map.put("valid", result);
        ObjectMapper mapper = new ObjectMapper();
        String resultString = "";
        try {
            resultString = mapper.writeValueAsString(map);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return resultString;
    }

 

 

方式二：

直接返回字符串,主要key/value值必须使用含有转义字符\的双引号，单引号无效 

 /*
     * 返回String类型的结果
     * 检查用户名的合法性,如果用户已经存在，返回false，否则返回true(返回json数据，格式为{"valid",true})
     */
    @RequestMapping(value = "/checkNameExistsMethod1", produces = "application/json;charset=UTF-8")
    public @ResponseBody
    String checkNameValidMethod1(@RequestParam String name) {
        boolean result = true;
     
        String resultString = "{\"result\":true}"; //注意一定是双引号 "{\"result\":\"success\"}"
      
        return resultString;
    }

 

三.返回任何预定义class类型的结果：

@RequestMapping(value = "/findEmployeebyName")
    public @ResponseBody
    Employee findEmployeebyName(String name) {
        List<Employee> lstEmployees = employeeService.getAllEmployees();
        for (Employee employee : lstEmployees) {
            if (employee.getName().equals(name))
                return employee;
        }
        return null;
    }

这里的Employ必须事先定义好。

四.使用HttpServletResponse对象的response.getWriter().write(xxx)方法

 

 

@RequestMapping(value="/forbiddenUser")
    public void forbiddenUser(int id,HttpServletRequest request,HttpServletResponse response) {
        String resultString="{\"result\":\"success\"}";//注意一定是双引号 "{\"result\":true}"    
        try {
            response.setContentType("application/json");
            response.getWriter().write(resultString);
        } catch (IOException e) {
            e.printStackTrace();
        }        
    }

spring4mvc返回json(bean,list,map)

　　因为spring3和spring4的mvc在前端返回json所需要的jar包不一样，所以索性写一篇关于spring4mvc在前端返回json的博文。

首先，新建一个web项目，项目格式如图所示：

 

convertJsonAction:springmvc的action类

inde.jsp：有三个按钮，分别返回bean，list和map对应的json

然后是引入的library：分别是spring-core，spring-mvc,spring-web,servlet> <servlet-name>DispatcherServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <!-- 将配置对应的springmvc文件设置在src根目录下 --> <param-value>classpath:springmvc.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>DispatcherServlet</servlet-name> <url-pattern>*.action</url-pattern> </servlet-mapping>

 

然后在src下面新建一个叫springmvc的xml文件，文件内容如图所示:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    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
        ">
    
</beans>

 

接着我们在ConvertJSonAction.java类中添加一个方法：

package com.mz.json;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * controller指明这是一个springmvc的action类
 * requestMapping是总的路径，所有访问这个action类中的方法必须通过/convert
 * @author asus
 *
 */
@Controller
@RequestMapping("/convert")
public class ConvertJsonAction {
    //responseBody是指返回的User是一个json对象(也可以是string或者xml对象)
    @RequestMapping("/bean2json")
    public @ResponseBody User bean2json() {
        User user = new User();
        user.setId(1);
        user.setUsername("Irasel");
        return user;
    }
}

 

 这是action的处理类，接着我们在springmvc中配置开启mvc的annotation和扫描标签:

<mvc:annotation-driven />
    <context:component-scan base-package="com.mz.json"></context:component-scan>

 

index.jsp中添加三个按钮，每一个按钮分别对应的返回一个bean对象的json，list对象的json和map对象的json:

 <!-- 点击返回一个bean对象的json -->
    <input type="button" value="bean2json"><br/>
    <!-- 点击返回一个list对象的json -->
    <input type="button" value="list2json"> <br/>
    <!-- 点击返回一个map对象的json -->
    <input type="button" value="map2json"><br/>

 

使用jquery的异步传输：

    $(':button:first').click(function(){
              var url = 'convert/bean2json.action';
              var arg =null;
              $.post(url,arg,function(returnData){
                  console.log(returnData);
              });
          });

 

效果如图所示：

接着是list和map的方法(不再粘贴效果图了，反正都差不多)

    @RequestMapping("/list2json")
    public @ResponseBody List<User> list2Json() {
        List<User> users = new ArrayList<User>();
        User user1 = new User();
        user1.setId(1);
        user1.setUsername("Irasel");
        User user2 = new User();
        user2.setId(2);
        user2.setUsername("路西法");
        User user3 = new User();
        user3.setId(3);
        user3.setUsername("Micheal");
        users.add(user1);
        users.add(user2);
        users.add(user3);
        return users;
    }
    @RequestMapping("/map2json")
    public @ResponseBody Map<String, Object> map2Json() {
        List<User> users = new ArrayList<User>();
        Map<String, Object> map = new HashMap<String, Object>();
        User user1 = new User();
        user1.setId(1);
        user1.setUsername("Irasel");
        User user2 = new User();
        user2.setId(2);
        user2.setUsername("路西法");
        User user3 = new User();
        user3.setId(3);
        user3.setUsername("Micheal");
        users.add(user1);
        users.add(user2);
        users.add(user3);
        map.put("row", users.size());
        map.put("users", users);
        return map;
        
    }

 

SpringMVC通过实体类返回json格式的字符串,并在前端显示

一.除了搭建springmvc框架需要的jar包外,还需要这两个jar包

jackson-core-asl-1.9.2.jar和jackson-mapper-asl-1.9.2.jar

二.web,.xml配置

1	classpath:spring-servlet.xml指定springmvc配置文件的位置

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<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5"     xmlns="http://java.sun.com/xml/ns/javaee"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">         <servlet>     <servlet-name>spring</servlet-name>     <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>      <init-param>         <param-name>contextConfigLocation</param-name>         <param-value>classpath:spring-servlet.xml</param-value>     </init-param>     <!-- 可以自定义servlet.xml配置文件的位置和名称，默认为WEB-INF目录下，名称为[<servlet-name>]-servlet.xml，如spring-servlet.xml     <init-param>         <param-name>contextConfigLocation</param-name>         <param-value>/WEB-INF/spring-servlet.xml</param-value>  默认     </init-param>     -->     <load-on-startup>1</load-on-startup> </servlet>    <servlet-mapping>     <servlet-name>spring</servlet-name>     <url-pattern>*.do</url-pattern> </servlet-mapping>   </web-app>

三.spring-servlet.xml配置

通过此配置,将实体类自动返回为json格式的数据

<?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"  
    xmlns:mvc="http://www.springframework.org/schema/mvc"  
   xsi:schemaLocation="  
       http://www.springframework.org/schema/beans   
       http://www.springframework.org/schema/beans/spring-beans-3.2.xsd  
       http://www.springframework.org/schema/context   
        http://www.springframework.org/schema/context/spring-context-3.2.xsd  
        http://www.springframework.org/schema/mvc      
        http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">  
     <!-- 启用spring mvc 注解 -->
    <context:annotation-config />
 
    <!-- 设置使用注解的类所在的jar包 -->
    <context:component-scan base-package="me.mvc,me.base"></context:component-scan>
 
    <!-- 完成请求和注解POJO的映射 -->
  <!--   <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" /> -->
 
    <!-- 对转向页面的路径解析。prefix：前缀， suffix：后缀 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/jsp/" p:suffix=".jsp" />

   <!-- 通过实体类返回json格式数据的关键配置 -->

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> <property name="messageConverters"> <list> <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"> <property name="supportedMediaTypes"> <list> <!--返回字符串格式json--> <value>application/json;charset=UTF-8</value> </list> </property> </bean> </list> </property> </bean> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <property name="maxUploadSize" value="102400000"></property> </bean> </beans>

四,后台java代码

package me.mvc;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import me.mvc.service.testmvcDao;
import net.sf.json.JSONArray;

import org.apache.struts2.ServletActionContext;
import org.springframework.http.HttpRequest;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.servlet.ModelAndView;

@Controller
@RequestMapping("/mvc/*")
public class testmvc {


    @RequestMapping(method=RequestMethod.GET,value="/hello22index.do")//第一步访问hello2页面
      public String index2() {
    
      return "hello2";
  }
    @ResponseBody
    @RequestMapping(method=RequestMethod.POST,value="/hello22.do")//第二步前台发送ajax请求调用此方法并返回json数据
      public User index2post(String testname1 ,HttpServletResponse response) throws IOException {
   
        System.out.println("*************:"+testname1);
  
        User u=new User();
        u.setUsername("name");
        u.setUserpassword("pass");
        return u;
}

}

五.前端页面

该方法sendajax()将向后台发送请求,调用index2post()方法,返回json数据格式

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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %>   <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html>   <head>    <script type="text/javascript" src="../../js/jquery-1.12.0.js"></script>     <base href="<%=basePath%>">           <title>My JSP 'hello2.jsp' starting page</title>           <meta http-equiv="pragma" content="no-cache">     <meta http-equiv="cache-control" content="no-cache">     <meta http-equiv="expires" content="0">        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">     <meta http-equiv="description" content="This is my page">    <script type="text/javascript" src="<%=path%>/js/jquery-1.12.0.js"></script></head>       <body>         <input type="text" name="testname" id="testname1">          <input type="button" value="ajax提交" onclick="sendajax()">    </form>   </body>   <script type="text/javascript">    function  sendajax()    {          var testname1=$("#testname1").val();        alert(testname1);        $.ajax({             type: "post",             url: "<%=path%>/mvc/hello22.do",              data: {testname1:testname1},                         dataType: "json",                        success: function (data) {               alert(data.username);                                 },             error: function (XMLHttpRequest, textStatus, errorThrown) {              alert("系统繁忙,请稍后重试!");                      }     });    }   </script> </html>