原文网址:SpringBoot--通过JSON传递请求参数--方法/实例_IT利刃出鞘的博客-CSDN博客
简介
本文用示例介绍SpringMVC如何通过JSON格式传递入参。
JSON格式使用post方式来请求,即:对应的注解为:@PostMapping。
@PostMapping注解的方法可以接收1个@RequestBody标记的参数和多个没有@RequestBody标记的参数。
代码
Entity
User.java
package com.example.demo.entity;
import lombok.Data;
import java.util.List;
@Data
public class User {
private String name;
private Integer age;
private String[] password;
private List<Integer> scoreArray;
}
Account.java
package com.example.demo.entity;
import lombok.Data;
import java.io.Serializable;
@Data
public class Account implements Serializable {
private String phoneNum;
private String[] emails;
}
Controller
package com.example.demo.controller;
import com.example.demo.entity.User;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import java.util.Arrays;
import java.util.List;
@RequestMapping("/json")
@RestController
public class JsonController {
@PostMapping("/1")
public User setUserNoAnnotation(User user, List<String> password, Integer[] scoreArray) {
printUser(user);
return user;
}
@RequestMapping("/2")
public User setUserAnnotation(@RequestBody User user) {
printUser(user);
return user;
}
@RequestMapping("/3")
public User setUserAnnotation1(@RequestBody User user, @RequestParam List<String> password, Integer[] scoreArray) {
System.out.println(password);
if (scoreArray != null) {
System.out.println(Arrays.asList(scoreArray));
} else {
System.out.println("scoreArray = null");
}
System.out.println();
printUser(user);
return user;
}
@RequestMapping("/4")
public User setUserAnnotation2(@RequestBody User user, @RequestBody List<String> password, @RequestBody Integer[] scoreArray) {
if (password != null) {
System.out.println(password);
} else {
System.out.println("password = null");
}
if (scoreArray != null) {
System.out.println(Arrays.asList(scoreArray));
} else {
System.out.println("scoreArray = null");
}
System.out.println();
printUser(user);
return user;
}
private void printUser(User user){
System.out.println("name : " + user.getName());
System.out.println("password : " + Arrays.asList(user.getPassword()));
System.out.println("scoreArray : " + user.getScoreArray());
System.out.println("acount.phoneNum : " + user.getAccount().getPhoneNum());
System.out.println("account.emails : " + Arrays.asList(user.getAccount().getEmails()));
}
}
测试
为方便测试,我用了knife4j。
测试前提
json的body
{
"name": "Jarvis",
"password": [
"ab",
"cd"
],
"scoreArray": [
99,
98
],
"account": {
"phoneNum": "123",
"emails": [
"123@qq.com",
"456@163.com"
]
}
}
正确的用法
1个RequestBody
0个@RequestBody,多个无@RequestBody
1个@RequestBody,多个无@RequestBody
错误的用法(会报错)
多个@RequestBody
后端报错信息
2022-09-20 22:04:45.857 WARN 3340 --- [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotReadableException: I/O error while reading input message; nested exception is java.io.IOException: Stream closed]
错误原因
每个方法只能有一个@RequestBody。使用@RequestBody把请求转化为特定的Object(在最后会关闭相应的流),所以在同一个方法中第二次使用@RequestBody是没用的,因为流已经关闭。
You cannot use it this way as only one @RequestBody per method is allowed. Using @RequestBody Spring converts incoming request body into the specified object (what closes the stream representing body at the end) so attempting to use @RequestBody second time in the same method makes no sense as stream has been already closed.
不带@RequestBody参数类型是List
后端错误信息
2022-09-20 23:19:11.044 ERROR 3340 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: No primary or default constructor found for interface java.util.List] with root cause
java.lang.NoSuchMethodException: java.util.List.<init>()
at java.lang.Class.getConstructor0(Class.java:3082) ~[na:1.8.0_201]
at java.lang.Class.getDeclaredConstructor(Class.java:2178) ~[na:1.8.0_201]
...(其他信息)
错误原因
不支持非@RequstBody的参数是List类型。(数组类型可以)。