020 SpringMVC返回Json

一：处理Json

1.添加jar包

　　添加json需要的包

2.后端返回json对用的对象或者集合

　　使用ResponseBody标签

 1 package com.spring.it.json;
 2 
 3 import java.util.Collection;
 4 
 5 import org.springframework.beans.factory.annotation.Autowired;
 6 import org.springframework.stereotype.Controller;
 7 import org.springframework.web.bind.annotation.RequestMapping;
 8 import org.springframework.web.bind.annotation.ResponseBody;
 9 
10 import com.spring.it.dao.EmployeeDao;
11 import com.spring.it.enties.Employee;
12 
13 @Controller
14 public class ReturnJsonHander {
15     @Autowired
16     private EmployeeDao employeeDao;
17     
18     @ResponseBody
19     @RequestMapping(value="/testJson")
20     public Collection<Employee> testJson() {
21         return employeeDao.getAll();
22     }
23 }

3.前段

 1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 2     pageEncoding="ISO-8859-1"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 7 <script type="text/javascript" src="scripts/jquery-1.9.1.min.js"></script>
 8 <script type="text/javascript">
 9     $(function(){
10         $("#testJson").click(function(){
11             var url=this.href;
12             var args={};
13             $.post(url,args,function(data){
14                 for(var i=0;i<data.length;i++){
15                     var id=data[i].id;
16                     var lastName=data[i].lastName;
17                     alert(id+":"+lastName);
18                 }
19             });
20             return false;
21         });
22     })
23 </script>
24 <title>Insert title here</title>
25 </head>
26 <body>
27     <br>
28     <a href="emps">list emps</a>
29     <br><br>
30     <a href="testJson" id="testJson">Test Json</a>
31 </body>
32 </html>

4.返回json

 1 [{
 2     "id": 1001,
 3     "lastName": "E-AA",
 4     "email": "aa@163.com",
 5     "gender": 1,
 6     "department": {
 7         "id": 101,
 8         "departmentName": "D-AA"
 9     },
10     "birth": null,
11     "salary": null
12 }, {
13     "id": 1002,
14     "lastName": "E-BB",
15     "email": "bb@163.com",
16     "gender": 1,
17     "department": {
18         "id": 102,
19         "departmentName": "D-BB"
20     },
21     "birth": null,
22     "salary": null
23 }, {
24     "id": 1003,
25     "lastName": "E-CC",
26     "email": "cc@163.com",
27     "gender": 0,
28     "department": {
29         "id": 103,
30         "departmentName": "D-CC"
31     },
32     "birth": null,
33     "salary": null
34 }, {
35     "id": 1004,
36     "lastName": "E-DD",
37     "email": "dd@163.com",
38     "gender": 0,
39     "department": {
40         "id": 104,
41         "departmentName": "D-DD"
42     },
43     "birth": null,
44     "salary": null
45 }, {
46     "id": 1005,
47     "lastName": "E-EE",
48     "email": "ee@163.com",
49     "gender": 1,
50     "department": {
51         "id": 105,
52         "departmentName": "D-EE"
53     },
54     "birth": null,
55     "salary": null
56 }]

5.请求

二：HttpMessageConverter

1.工作原理

　　使用HttpMessageConverter<T>将请求信息转化并绑定到处理方法的入参中，或将响应结果转化为对应类型的响应信息。

　　主要提供了两种途径：

　　@RequestBody与@ResponseBody对处理方法进行标注

　　HttpEntity与ResponseEntity作为处理方法的入参或返回值

三：案例--上传--注解

1.index

 1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 2     pageEncoding="ISO-8859-1"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 7 <script type="text/javascript" src="scripts/jquery-1.9.1.min.js"></script>
 8 <script type="text/javascript">
 9     $(function(){
10         $("#testJson").click(function(){
11             var url=this.href;
12             var args={};
13             $.post(url,args,function(data){
14                 for(var i=0;i<data.length;i++){
15                     var id=data[i].id;
16                     var lastName=data[i].lastName;
17                     alert(id+":"+lastName);
18                 }
19             });
20             return false;
21         });
22     })
23 </script>
24 <title>Insert title here</title>
25 </head>
26 <body>
27     <br>
28     <a href="emps">list emps</a>
29     <br><br>
30     <a href="testJson" id="testJson">Test Json</a>
31     <br><br>
32     <form action="testHttpMessageConverter" method="post" enctype="multipart/form-data">
33         File:<input type="file" name="file"/>
34         Desc:<input type="text" name="desc"/>
35         <input type="submit" value=Submit"">
36     </form>
37     
38 </body>
39 </html>

2.处理方法

 1 package com.spring.it.json;
 2 
 3 import java.util.Collection;
 4 import java.util.Date;
 5 
 6 import org.springframework.beans.factory.annotation.Autowired;
 7 import org.springframework.stereotype.Controller;
 8 import org.springframework.web.bind.annotation.RequestBody;
 9 import org.springframework.web.bind.annotation.RequestMapping;
10 import org.springframework.web.bind.annotation.ResponseBody;
11 
12 import com.spring.it.dao.EmployeeDao;
13 import com.spring.it.enties.Employee;
14 
15 @Controller
16 public class ReturnJsonHander {
17     @Autowired
18     private EmployeeDao employeeDao;
19     
20     @ResponseBody
21     @RequestMapping(value="/testJson")
22     public Collection<Employee> testJson() {
23         return employeeDao.getAll();
24     }
25     
26     @ResponseBody
27     @RequestMapping(value="/testHttpMessageConverter")
28     public String testHttpMessage(@RequestBody String body) {
29         System.out.println("body:"+body);
30         return "helloWorld"+new Date();
31     }
32 }

3.效果

四：案例--下载--处理方法

1.请求

　　<a href="testResponseEntity">Test ResponseEntity</a>

2.处理方法

 1 package com.spring.it.json;
 2 
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5 import java.util.Collection;
 6 import java.util.Date;
 7 
 8 import javax.servlet.ServletContext;
 9 import javax.servlet.http.HttpSession;
10 
11 import org.springframework.beans.factory.annotation.Autowired;
12 import org.springframework.http.HttpHeaders;
13 import org.springframework.http.HttpStatus;
14 import org.springframework.http.ResponseEntity;
15 import org.springframework.stereotype.Controller;
16 import org.springframework.web.bind.annotation.RequestBody;
17 import org.springframework.web.bind.annotation.RequestMapping;
18 import org.springframework.web.bind.annotation.ResponseBody;
19 
20 import com.spring.it.dao.EmployeeDao;
21 import com.spring.it.enties.Employee;
22 
23 @Controller
24 public class ReturnJsonHander {
25     @Autowired
26     private EmployeeDao employeeDao;
27     
28     @ResponseBody
29     @RequestMapping(value="/testJson")
30     public Collection<Employee> testJson() {
31         return employeeDao.getAll();
32     }
33     
34     @ResponseBody
35     @RequestMapping(value="/testHttpMessageConverter")
36     public String testHttpMessage(@RequestBody String body) {
37         System.out.println("body:"+body);
38         return "helloWorld"+new Date();
39     }
40     
41     @RequestMapping("/testResponseEntity")
42     public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws Exception{
43         byte[] body=null;
44         ServletContext context=session.getServletContext();
45         InputStream in=context.getResourceAsStream("/file/ADC.txt");
46         body=new byte[in.available()];
47         in.read(body);
48         HttpHeaders headers=new HttpHeaders();
49         headers.add("Content-Disposition", "attament;fileName=ADC.txt");
50         HttpStatus status=HttpStatus.OK;
51         ResponseEntity<byte[]> response=new ResponseEntity<>(body,headers,status);
52         return response;
53     }
54     
55     
56 }

3.效果

　　浏览器上：

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原文地址：https://www.cnblogs.com/juncaoit/p/8733701.html