上一次的介绍，主要围绕如何统一去捕获异常，以及为每一种异常添加自己的Mapper实现，并且我们知道，当在ExceptionMapper中返回非200的Response，不支持application/json的响应类型，而是写死的text/plain类型。

Filter为二方包异常手动捕获

参考：https://blog.csdn.net/2401_84048290/article/details/138105184

我们来看看dubbo的源码进行分析，如果Dubbo的provider端抛出异常（Throwable），则会被 provider端的ExceptionFilter拦截到，执行以下invoke方法，里面有个实现Listener类，重写了onResponse，我们可以自定义filter来覆盖原来的ExceptionFilter，把自定义的异常通过RuntimeException进行包裹，然后在Mapper中进行统一的捕获。

添加CustomExceptionFilter类型，实现Filter和BaseFilter.Listener，重写onResponse方法，添加自定义代码，如下：


public class CustomExceptionFilter implements Filter, BaseFilter.Listener {
    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
          exception = appResponse.getException();
        String className = exception.getClass().getName();
        // 本项目的异常也直接抛出
        if (className.startsWith("com.myself.")) {
          appResponse.setException(new RuntimeException(exception));
          return;
        }
        // 其它原来ExceptionFilter中的代码
    }
}
public class CustomExceptionFilter implements Filter, BaseFilter.Listener {
    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
          exception = appResponse.getException();
        String className = exception.getClass().getName();

        // 本项目的异常也直接抛出
        if (className.startsWith("com.myself.")) {
          appResponse.setException(new RuntimeException(exception));
          return;
        }
        // 其它原来ExceptionFilter中的代码
    }
}
public class CustomExceptionFilter implements Filter, BaseFilter.Listener {
    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
        	exception = appResponse.getException();
				String className = exception.getClass().getName();

				// 本项目的异常也直接抛出
				if (className.startsWith("com.myself.")) {
					appResponse.setException(new RuntimeException(exception));
					return;
				}
				// 其它原来ExceptionFilter中的代码
    }
}

META-INF中注册这个过滤器resources/META-INF/dubbo/org.apache.dubbo.rpc.Filter


customExceptionFilter=com.xxx.register.exception.filter.CustomExceptionFilter
customExceptionFilter=com.xxx.register.exception.filter.CustomExceptionFilter
customExceptionFilter=com.xxx.register.exception.filter.CustomExceptionFilter

配置中文中注册，并移除默认的resources/application.properties


# 自定义过滤器,上面-exception就是dubbo默认的处理异常的filter，前面-号就代表去除,注意：不需要加双引号
dubbo.provider.filter=customExceptionFilter,-exception
# 自定义过滤器,上面-exception就是dubbo默认的处理异常的filter，前面-号就代表去除,注意：不需要加双引号
dubbo.provider.filter=customExceptionFilter,-exception
# 自定义过滤器,上面-exception就是dubbo默认的处理异常的filter，前面-号就代表去除,注意：不需要加双引号
dubbo.provider.filter=customExceptionFilter,-exception

一个Mapper处理所有自定义异常

配置文件中指定mapper，resources/application.properties


dubbo.protocols.http.extension=com.xxx.register.exception.mapper.CustomExceptionMapper
dubbo.protocols.http.extension=com.xxx.register.exception.mapper.CustomExceptionMapper
dubbo.protocols.http.extension=com.xxx.register.exception.mapper.CustomExceptionMapper

mapper源码如下


@Provider
public class DbViolationExceptionMapper implements ExceptionMapper<RuntimeException> {
  @Override
  public Response toResponse(RuntimeException exception) {
    Map<String, String> map = MapUtil.<String, String>builder().put("error", exception.getMessage()).build();
    if (exception.getCause() instanceof ForbiddenException) {
      return Response.status(Response.Status.FORBIDDEN).entity(map).type(MediaType.APPLICATION_JSON).build();
    }
    if (exception.getCause() instanceof CustomException) {
      return Response.status(Response.Status.BAD_REQUEST).entity(map).type(MediaType.APPLICATION_JSON).build();
    }
    if (exception.getCause() instanceof IdentityBrokerException) {
      return Response.status(Response.Status.UNAUTHORIZED).entity(map).type(MediaType.APPLICATION_JSON).build();
    }
    if (exception.getCause() instanceof UniqueException) {
      return Response.status(Response.Status.SERVICE_UNAVAILABLE).entity(map).type(MediaType.APPLICATION_JSON)
          .build();
    }
    return Response.status(Response.Status.SERVICE_UNAVAILABLE)
        .entity(MapUtil.builder().put("error", exception.getMessage()).build()).type(MediaType.APPLICATION_JSON)
        .encoding("utf-8").build();// 非200的请求，这个type无效，一直是text/plain
  }
}
@Provider
public class DbViolationExceptionMapper implements ExceptionMapper<RuntimeException> {

  @Override
  public Response toResponse(RuntimeException exception) {
    Map<String, String> map = MapUtil.<String, String>builder().put("error", exception.getMessage()).build();
    if (exception.getCause() instanceof ForbiddenException) {
      return Response.status(Response.Status.FORBIDDEN).entity(map).type(MediaType.APPLICATION_JSON).build();
    }
    if (exception.getCause() instanceof CustomException) {
      return Response.status(Response.Status.BAD_REQUEST).entity(map).type(MediaType.APPLICATION_JSON).build();
    }
    if (exception.getCause() instanceof IdentityBrokerException) {
      return Response.status(Response.Status.UNAUTHORIZED).entity(map).type(MediaType.APPLICATION_JSON).build();
    }
    if (exception.getCause() instanceof UniqueException) {
      return Response.status(Response.Status.SERVICE_UNAVAILABLE).entity(map).type(MediaType.APPLICATION_JSON)
          .build();
    }
    return Response.status(Response.Status.SERVICE_UNAVAILABLE)
        .entity(MapUtil.builder().put("error", exception.getMessage()).build()).type(MediaType.APPLICATION_JSON)
        .encoding("utf-8").build();// 非200的请求，这个type无效，一直是text/plain

  }

}
@Provider
public class DbViolationExceptionMapper implements ExceptionMapper<RuntimeException> {

	@Override
	public Response toResponse(RuntimeException exception) {
		Map<String, String> map = MapUtil.<String, String>builder().put("error", exception.getMessage()).build();
		if (exception.getCause() instanceof ForbiddenException) {
			return Response.status(Response.Status.FORBIDDEN).entity(map).type(MediaType.APPLICATION_JSON).build();
		}
		if (exception.getCause() instanceof CustomException) {
			return Response.status(Response.Status.BAD_REQUEST).entity(map).type(MediaType.APPLICATION_JSON).build();
		}
		if (exception.getCause() instanceof IdentityBrokerException) {
			return Response.status(Response.Status.UNAUTHORIZED).entity(map).type(MediaType.APPLICATION_JSON).build();
		}
		if (exception.getCause() instanceof UniqueException) {
			return Response.status(Response.Status.SERVICE_UNAVAILABLE).entity(map).type(MediaType.APPLICATION_JSON)
					.build();
		}
		return Response.status(Response.Status.SERVICE_UNAVAILABLE)
				.entity(MapUtil.builder().put("error", exception.getMessage()).build()).type(MediaType.APPLICATION_JSON)
				.encoding("utf-8").build();// 非200的请求，这个type无效，一直是text/plain

	}

}