在spring中手写全局异常拦截器

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface ExceptionAdvice {
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ExceptionHandler {
  Class<? extends Throwable>[] value();
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ExceptionIntercept {
}

@Data
public class BaseResponse<T> {
  private Integer code;
  private String message;
  private T data;

  public BaseResponse(Integer code, String message) {
    this.code = code;
    this.message = message;
  }
}

public class ExceptionMethodPool {
  private List<ExceptionMethod> methods;
  private Object excutor;

  public ExceptionMethodPool(Object excutor) {
    this.methods = new ArrayList<ExceptionMethod>();
    this.excutor = excutor;
  }

  public Object getExcutor() {
    return excutor;
  }

  public void add(Class<? extends Throwable> clazz, Method method) {
    methods.add(new ExceptionMethod(clazz, method));
  }
		
 	//按序查找能够处理该异常的处理器
  public Method obtainMethod(Throwable throwable) {
    return methods
        .stream()
        .filter(e -> e.getClazz().isAssignableFrom(throwable.getClass()))
        .findFirst()
        .orElseThrow(() ->new RuntimeException("没有找到对应的异常处理器"))
        .getMethod();
  }

  @AllArgsConstructor
  @Getter
  class ExceptionMethod {
    private Class<? extends Throwable> clazz;
    private Method method;
  }
}

@Component
public class ExceptionBeanPostProcessor implements BeanPostProcessor {
  private ExceptionMethodPool exceptionMethodPool;
  @Autowired
  private ConfigurableApplicationContext context;

  @Override
  public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
    Class<?> clazz = bean.getClass();
    ExceptionAdvice advice = clazz.getAnnotation(ExceptionAdvice.class);
    if (advice == null) return bean;
    if (exceptionMethodPool != null) throw new RuntimeException("不允许有两个异常定义类");
    exceptionMethodPool = new ExceptionMethodPool(bean);

    //保持处理异常方法顺序
    Arrays.stream(clazz.getDeclaredMethods())
        .filter(method -> method.getAnnotation(ExceptionHandler.class) != null)
        .forEach(method -> {
          ExceptionHandler exceptionHandler = method.getAnnotation(ExceptionHandler.class);
          Arrays.stream(exceptionHandler.value()).forEach(c -> exceptionMethodPool.add(c,method));
        });
    //注册进spring容器
    context.getBeanFactory().registerSingleton("exceptionMethodPool",exceptionMethodPool);
    return bean;
  }
}

@Component
public class ExceptionProcessor {
  @Autowired
  private ExceptionMethodPool exceptionMethodPool;

  public BaseResponse process(Throwable e) {
    return (BaseResponse) FunctionUtil.computeOrGetDefault(() ->{
      Method method = exceptionMethodPool.obtainMethod(e);
      method.setAccessible(true);
      return method.invoke(exceptionMethodPool.getExcutor(),e);
    },new BaseResponse(0,"未知错误"));
  }
}

@Aspect
@Component
public class ExceptionInterceptAop {
  @Autowired
  private ExceptionProcessor exceptionProcessor;
 
  @Pointcut("@annotation(com.example.exception.intercept.ExceptionIntercept)")
  public void pointcut() {
  }
 
  @Around("pointcut()")
  public Object around(ProceedingJoinPoint point) {
    return computeAndDealException(() -> point.proceed(),
        e -> exceptionProcessor.process(e));
  }
 
  public static <R> R computeAndDealException(ThrowExceptionSupplier<R> supplier, Function<Throwable, R> dealFunc) {
    try {
      return supplier.get();
    } catch (Throwable e) {
      return dealFunc.apply(e);
    }
  }
  @FunctionalInterface
  public interface ThrowExceptionSupplier<T> {
    T get() throws Throwable;
  }
}

@ExceptionAdvice
public class ExceptionConfig {
  @ExceptionHandler(value = NullPointerException.class)
  public BaseResponse process(NullPointerException e){
    return new BaseResponse(0,"NPE");
  }

  @ExceptionHandler(value = Exception.class)
  public BaseResponse process(Exception e){
    return new BaseResponse(0,"Ex");
  }
  
}

@RestController
public class TestControler {

  @RequestMapping("/test")
  @ExceptionIntercept
  public BaseResponse test(@RequestParam("a") Integer a){
    if (a == 1){
      return new BaseResponse(1,a+"");
    }
    else if (a == 2){
      throw new NullPointerException();
    }
    else throw new RuntimeException();
  }
}