springboot的@RestControllerAdvice作用和捕获自定义异常返回自定义结果案例

Posted on by hackdl

一、@RestControllerAdvice是什么?

@RestContrllerAdvice是一种组合注解，由@ControllerAdvice，@ResponseBody组成

@ControllerAdvice继承了@Component，反过来，可以理解为@RestContrllerAdvice本质上就是@Component

1.1 @Component是什么？

本质上是一个类，泛指各种组件，就是说当我们的类不属于各种归类的时候(不属于@Controller，@Service等的时候)，我们就可以使用@Component

作用就是实现bean注入，利用这个注解可以取代spring的xml配置文件

1.2 @Component案例

1.2.1 准备的jar

         
            com.alibaba
            fastjson
            1.2.75

1.2.2 controller

@RestController
public class TestController {

    @Autowired
    private TestService testService;

    @GetMapping("/test3")
    public String test3() {
        return testService.test();
    }
}

1.2.3 接口

public interface TestService {
    
    String test();
}

1.2.4组件

@Component
public class TestServiceImpl implements TestService {

    @Autowired
    private ObjectMapper objectMapper;

    @Override
    public String test() {
        String b = null;
        try {
            b =  objectMapper.writeValueAsString("a");
            System.out.println(b);
        } catch (Exception e) {
        }
        return b;
    }
}

二、@RestControllerAdvice有什么作用？

  1. 自定义客户端返回格式

  1. 捕获客户端返回异常

三、@RestControllerAdvice案例和使用场景

捕获客户端返回异常案例(自定义返回异常)

3.1 未自定义捕获异常之前

3.2 自定义捕获异常以后

3.3代码实现自定义捕获异常

3.3.1 自定义异常枚举

public interface BaseCodeMsg {

    String getCode();

    String getMsg();
}
public enum PlatformExceptionMsgEnum implements BaseCodeMsg {

    /**
     * base平台返回的异常信息
     */
    SELECT_NULL("000000001", "查询数据为空"),
    INVOKE_IS_REJECT("00000002", "请求被拒绝"),
    ILLEGAL_ARGUMENT_FORMAT("000000003", "非法参数格式"),
    ILLEGAL_ARGUMENT("000000004","数据非法"),
    SYSTEM_EXCEPTION("000000005", "系统异常");

    /**
     * 错误码
     */
    private final String code;

    /**
     * 错误信息
     */
    private final String msg;

    PlatformExceptionMsgEnum(String code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    @Override
    public String getCode() {
        return code;
    }

    @Override
    public String getMsg() {
        return msg;
    }


}

3.3.2 自定义平台异常

public abstract class AbstractApiException extends RuntimeException{

    public AbstractApiException() {

    }

    public abstract String getCode();

    public abstract String getMsg();
}
public class PlatformException extends AbstractApiException {

    private String code;

    private String msg;

    public PlatformException(BaseCodeMsg baseCodeMsg) {
        code = baseCodeMsg.getCode();
        msg = baseCodeMsg.getMsg();
    }

    public static void throwException(BaseCodeMsg baseCodeMsg) {
        throw new PlatformException(baseCodeMsg.getCode(), baseCodeMsg.getMsg());
    }

    public static void throwException(BaseCodeMsg baseCodeMsg, String msg) {
        throw new PlatformException(baseCodeMsg.getCode(), StringUtils.isEmpty(baseCodeMsg.getMsg()) ? msg : baseCodeMsg.getMsg());
    }

    public static void throwException(String code, String msg) {
        throw new PlatformException(code, msg);
    }

    public static void throwException(String msg) {
        throw new PlatformException(PlatformExceptionMsgEnum.SYSTEM_EXCEPTION.getCode(), msg);
    }

    public PlatformException(String code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    @Override
    public String getCode() {
        return code;
    }

    @Override
    public String getMsg() {
        return msg;
    }
}

3.3.3 自定义返回类

@Data
public class BaseResult implements Serializable {
    private static final long serialVersionUID = 1L;

    private String code;

    private String msg;

    private String traceId;

    private T data;

    public boolean isSuccess() {
        return PlatformExceptionMsgEnum.SUCCESS.getCode().equals(this.code);
    }
    public static BaseResult ok() {
        return restBaseResult((Object)null, PlatformExceptionMsgEnum.SUCCESS);
    }

    public static  BaseResult ok(T data) {
        return restBaseResult(data, PlatformExceptionMsgEnum.SUCCESS);
    }

    public static BaseResult fail() {
        return restBaseResult((Object)null, PlatformExceptionMsgEnum.SYSTEM_ERROR);
    }

    public static BaseResult fail(BaseCodeMsg baseCodeMsg) {
        return restBaseResult((Object)null, baseCodeMsg);
    }

    public static BaseResult fail(String code, String msg) {
        return restBaseResult((Object)null, code, msg);
    }


    private static  BaseResult restBaseResult(T data, BaseCodeMsg baseCodeMsg) {
        return restBaseResult(data, baseCodeMsg.getCode(), baseCodeMsg.getMsg());
    }

    private static  BaseResult restBaseResult(T data, String code, String msg) {
        BaseResult apiBaseResult = new BaseResult();
        apiBaseResult.setCode(code);
        apiBaseResult.setData(data);
        apiBaseResult.setMsg(msg);
        apiBaseResult.setTraceId(MDC.get("traceId"));
        return apiBaseResult;
    }

    public BaseResult() {
    }
}

3.3.4 controller层

@RestController
public class TestController {

    @GetMapping("/test")
    public void test() {
        PlatformException.throwException(PlatformExceptionMsgEnum.SYSTEM_EXCEPTION);
    }

}

3.3.5 @RestControllerAdvice

@RestControllerAdvice
@Configuration
public class GlobalExceptionHandler {
    private static final Logger log = LoggerFactory.getLogger(GlobalExceptionHandler.class);
    private MessageSource messageSource;


    /**
     * 捕获全局异常类
     *
     * @param e
     * @return
     */
    @ExceptionHandler({MethodArgumentNotValidException.class})
    public BaseResult handle(MethodArgumentNotValidException e) {
        if (e.getBindingResult().hasErrors()) {
            String msg = ((ObjectError) e.getBindingResult().getAllErrors().get(0)).getDefaultMessage();
            return BaseResult.fail(PlatformExceptionMsgEnum.ILLEGAL_ARGUMENT.getCode(), this.getI18nMsg(msg));
        } else {
            log.info(e.getMessage(), e);
            return BaseResult.fail(PlatformExceptionMsgEnum.ILLEGAL_ARGUMENT.getCode(), this.getI18nMsg(PlatformExceptionMsgEnum.ILLEGAL_ARGUMENT.getMsg()));
        }
    }


    /**
     * 捕获API调用接口的异常类
     *
     * @param e
     * @return
     */
    @ExceptionHandler(AbstractApiException.class)
    public BaseResult abstractApiException(AbstractApiException e) {
        return BaseResult.fail(e.getCode(), e.getMsg());
    }

    /**
     * 前端传入的参数和后端传入的参数接收不匹配
     *
     * @param e
     * @return
     */
    @ExceptionHandler({HttpMessageNotReadableException.class})
    public BaseResult handle(HttpMessageNotReadableException e) {
        log.warn(e.getMessage(), e);
        return BaseResult.fail(PlatformExceptionMsgEnum.ILLEGAL_ARGUMENT_FORMAT.getCode(), this.getI18nMsg(PlatformExceptionMsgEnum.ILLEGAL_ARGUMENT_FORMAT.getMsg()));
    }

    /**
     * 子类异常(相当于子类不能抛出比父类更广泛异常)
     *
     * @param e
     * @return
     */
    @ExceptionHandler({UndeclaredThrowableException.class})
    public BaseResult handle(UndeclaredThrowableException e) {
        log.warn(e.getMessage(), e);
        return BaseResult.fail(PlatformExceptionMsgEnum.INVOKE_IS_REJECT.getCode(), this.getI18nMsg(PlatformExceptionMsgEnum.INVOKE_IS_REJECT.getMsg()));
    }

    /**
     * 异常捕获
     *
     * @param e 捕获的异常，封装返回的对象
     * @return
     */
    @ExceptionHandler(Exception.class)
    public BaseResult handleException(Exception e) {
        log.warn(e.getMessage(), e);
        StringJoiner joiner = new StringJoiner(":");
        joiner.add(this.getI18nMsg(PlatformExceptionMsgEnum.INVOKE_IS_REJECT.getMsg())).add(e.getMessage());
        return BaseResult.fail(PlatformExceptionMsgEnum.SYSTEM_EXCEPTION.getCode(), joiner.toString());
    }

    private String getI18nMsg(String msg) {
        try {
            return this.messageSource.getMessage(msg, (Object[]) null, LocaleContextHolder.getLocale());
        } catch (NoSuchMessageException var3) {
            return msg;
        }
    }

    public GlobalExceptionHandler(MessageSource messageSource) {
        this.messageSource = messageSource;
    }
}

3.4 代码实现自定义返回结果

没有自定义返回结果之前

自定义返回结果以后

3.4.1 controller

@RestController
public class TestController {

    @GetMapping("/test2")
    public String test2() {
        return "test2";
    }

}

3.4.2 返回结果来

BaseResult返回结果类在上面，对应需要导入json的jar也在上面

3.4.3 @RestControllerAdvice

@RestControllerAdvice(
        annotations = {RestController.class}
)
@Configuration
public class BaseResultResponseAdvice implements ResponseBodyAdvice {

    @Autowired
    private ObjectMapper objectMapper;

    /**
     * @param methodParameter 利用这个参数判断注解信息
     * @param aClass
     * @return
     */
    @Override
    public boolean supports(MethodParameter methodParameter, Class extends HttpMessageConverter>> aClass) {
        return true;
    }

    /**
     * @param body               原controller需要返回的内容
     * @param methodParameter    利用这个参数判断注解信息
     * @param mediaType
     * @param aClass
     * @param serverHttpRequest
     * @param serverHttpResponse
     * @return
     */

    @Override
    public Object beforeBodyWrite(Object body, MethodParameter methodParameter, MediaType mediaType, Class extends HttpMessageConverter>> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
        try {
            if (methodParameter.getParameterType() == ResponseEntity.class) {
                return body;
            } else if (methodParameter.getParameterType() == BaseResult.class) {
                return body;
            } else if (methodParameter.getParameterType() == String.class) {
                serverHttpResponse.getHeaders().setContentType(MediaType.APPLICATION_JSON);
                return this.objectMapper.writeValueAsString(BaseResult.ok(body));
            } else {
                return BaseResult.ok(body);
            }
        } catch (Throwable t) {
            return BaseResult.fail();
        }
    }
}

四、拓展

@RestControllerAdvice的使用还可以指定对应的注解、包，类。比如你需要返回自定义结果格式，可以指定@RestController层使用，如果你要指定类和包也可以

4.1 指定注解

@RestControllerAdvice(
        annotations = {RestController.class}
)

4.2 指定类

@RestControllerAdvice(
        basePackageClasses = TestController.class
)

4.3 指定包

@RestControllerAdvice(
        basePackages = "com.common.base.controller"
)

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