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
}
参考文章：
https://blog.csdn.net/lrt890424/article/details/83624761
https://www.cnblogs.com/Purgeyao/p/11599810.html
