使用場景
我們在編寫代碼時候，可能需要給前端一個相對統一的格式，所以經常用一個Result類來封裝結果。
@GetMapping("result")
public Result get1() {
return Result.success(new Person("tom"));
}
采用以下方式處理，就不用每次調用Result.success方法了
使用方法
1、定義注解，組合@ResponseBody
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
@Documented
@ResponseBody//繼承
public @interface ResponseResultBody {
}
2、實現ResponseBodyAdvice接口
這里也包含了統一異常處理
import com.lexiaoyao.controlleradvice_.annos.ResponseResultBody;
import com.lexiaoyao.controlleradvice_.model.Result;
import com.lexiaoyao.controlleradvice_.model.ResultException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
import java.lang.annotation.Annotation;
@RestControllerAdvice
@Slf4j
public class ResponseResultBodyAdvice implements ResponseBodyAdvice<Object> {
private static final Class<? extends Annotation> ANNOTATION_TYPE = ResponseResultBody.class;
/**
* 判斷類或者方法是否使用了 @ResponseResultBody
*/
@Override
public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
return AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ANNOTATION_TYPE) || returnType.hasMethodAnnotation(ANNOTATION_TYPE);
}
/**
* 當類或者方法使用了 @ResponseResultBody 就會調用這個方法
*/
@Override
public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
// 防止重復包裹的問題出現
if (body instanceof Result) {
return body;
}
return Result.success(body);
}
/**
* 提供對標准Spring MVC異常的處理
*
* @param ex the target exception
*/
@ExceptionHandler(Exception.class)
public final ResponseEntity<Result<?>> exceptionHandler(Exception ex) {
log.error("ExceptionHandler: {}", ex.getMessage());
HttpHeaders headers = new HttpHeaders();
if (ex instanceof ResultException) {
return this.handleResultException((ResultException) ex, headers);
}
// TODO: 這里可以自定義其他的異常攔截
return this.handleException(ex, headers);
}
/**
* 對ResultException類返回返回結果的處理
*/
private ResponseEntity<Result<?>> handleResultException(ResultException ex, HttpHeaders headers) {
Result<?> body = Result.failure(ex.getResultStatus());
HttpStatus status = ex.getResultStatus().getHttpStatus();
return this.handleExceptionInternal(ex, body, headers, status);
}
/**
* 異常類的統一處理
*/
private ResponseEntity<Result<?>> handleException(Exception ex, HttpHeaders headers) {
Result<?> body = Result.failure();
HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
return this.handleExceptionInternal(ex, body, headers, status);
}
private ResponseEntity<Result<?>> handleExceptionInternal(
Exception ex, Result<?> body, HttpHeaders headers, HttpStatus status) {
return new ResponseEntity<>(body, headers, status);
}
}
3、在需要包裝的controller上加上注解
@RestController
@ResponseResultBody//自定義的統一處理注解
public class AppController {
/**
* 會被自動包裝為result
*
* @return
*/
@GetMapping
public Person get() {
return new Person("tom");
}
@GetMapping("result")
public Result get1() {
return Result.success(new Person("tom"));
}
@PostMapping
public void post() {
throw new ResultException(ResultStatus.INTERNAL_SERVER_ERROR);
}
}