全局统一返回RESTful风格数据，主要是实现ResponseBodyAdvice接口的方法，对返回值在输出之前进行修改。
使用注解@RestControllerAdvice拦截异常并统一处理。
开发环境：
IntelliJ IDEA 2019.2.2
jdk1.8
Spring Boot 2.2.2
1、创建一个SpringBoot项目，pom.xml引用的依赖包如下
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.62</version>
</dependency>
2、定义一个返回类
package com.example.response.entity;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import java.io.Serializable;
@Data
@NoArgsConstructor
@ToString
public class ResponseData<T> implements Serializable {
/**
* 状态码：0-成功，1-失败
* */
private int code;
/**
* 错误消息，如果成功可为空或SUCCESS
* */
private String msg;
/**
* 返回结果数据
* */
private T data;
public static ResponseData success() {
return success(null);
}
public static ResponseData success(Object data) {
ResponseData result = new ResponseData();
result.setCode(0);
result.setMsg("SUCCESS");
result.setData(data);
return result;
}
public static ResponseData fail(String msg) {
return fail(msg,null);
}
public static ResponseData fail(String msg, Object data) {
ResponseData result = new ResponseData();
result.setCode(1);
result.setMsg(msg);
result.setData(data);
return result;
}
}
3、统一拦截接口返回数据
新建一个类GlobalResponseHandler，用注解@RestControllerAdvice，并且实现ResponseBodyAdvice接口的方法，其中方法supports可以判断哪些需要拦截，方法beforeBodyWrite可以对返回值在输出之前进行修改，从而实现返回统一的接口数据。
package com.example.response.config;
import com.alibaba.fastjson.JSON;
import com.example.response.entity.ResponseData;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
/**
* 实现ResponseBodyAdvice接口，可以对返回值在输出之前进行修改
*/
@RestControllerAdvice
public class GlobalResponseHandler implements ResponseBodyAdvice<Object> {
//判断支持的类型
@Override
public boolean supports(MethodParameter methodParameter, Class<? extends HttpMessageConverter<?>> aClass) {
// 检查注解是否存在，存在则忽略拦截
if (methodParameter.getDeclaringClass().isAnnotationPresent(IgnorReponseAdvice.class)) {
return false;
}
if (methodParameter.getMethod().isAnnotationPresent(IgnorReponseAdvice.class)) {
return false;
}
return true;
}
@Override
public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class<? extends HttpMessageConverter<?>> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
// 判断为null构建ResponseData对象进行返回
if (o == null) {
return ResponseData.success();
}
// 判断是ResponseData子类或其本身就返回Object o本身，因为有可能是接口返回时创建了ResponseData,这里避免再次封装
if (o instanceof ResponseData) {
return (ResponseData<Object>) o;
}
// String特殊处理，否则会抛异常
if (o instanceof String) {
return JSON.toJSON(ResponseData.success(o)).toString();
}
return ResponseData.success(o);
}
}
新建自定义注解IgnorReponseAdvice
package com.example.response.config;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface IgnorReponseAdvice {
}
4、统一异常处理
package com.example.response.exception;
import com.example.response.entity.ResponseData;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
@RestControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(Exception.class)
public ResponseData exceptionHandler(Exception e) {
e.printStackTrace();
return ResponseData.fail("服务器异常：" + e.getMessage());
}
}
5、新建一个测试用的实体类
package com.example.response.entity;
import lombok.Data;
@Data
public class User {
private Long userId;
private String userName;
public User(Long userId, String userName){
this.userId = userId;
this.userName = userName;
}
}
6、新建一个测试用的控制器类
package com.example.response.controller;
import com.example.response.config.IgnorReponseAdvice;
import com.example.response.entity.ResponseData;
import com.example.response.entity.User;
import org.springframework.web.bind.annotation.*;
import java.util.ArrayList;
import java.util.List;
@RestController
public class DemoController {
@GetMapping("user")
public User user() {
User u = new User(100L, "u1");
return u;
}
@GetMapping("userList")
public List<User> userList(){
List<User> list = new ArrayList<User>();
list.add(new User(100L, "u1"));
list.add(new User(200L, "u2"));
return list;
}
@GetMapping("test1")
public String test1(){
return "test1";
}
@GetMapping("test2")
public ResponseData test2(){
return ResponseData.success("test2");
}
@IgnorReponseAdvice
@GetMapping("test3")
public String test3() {
return "test3";
}
@GetMapping("test4")
public String test4() {
Integer x = 1 / 0;
return x.toString();
}
@GetMapping("test5")
public String test5() throws Exception {
throw new Exception("自定义异常信息");
}
}
7、用Postman测试
(1)请求http://localhost:8080/user，返回
{
"code": 0,
"msg": "SUCCESS",
"data": {
"userId": 100,
"userName": "u1"
}
}
(2)请求http://localhost:8080/userList，返回
{
"code": 0,
"msg": "SUCCESS",
"data": [
{
"userId": 100,
"userName": "u1"
},
{
"userId": 200,
"userName": "u2"
}
]
}
(3)请求http://localhost:8080/tes1，返回
{"msg":"SUCCESS","code":0,"data":"test1"}
(4)请求http://localhost:8080/test2，返回
{
"code": 0,
"msg": "SUCCESS",
"data": "test2"
}
(5)请求http://localhost:8080/test3，返回
test3
(6)请求http://localhost:8080/test4，返回
{
"code": 1,
"msg": "服务器异常：/ by zero",
"data": null
}
(7)请求http://localhost:8080/test5，返回
{
"code": 1,
"msg": "服务器异常：自定义异常信息",
"data": null
}
