dubbo Filter 过滤器（拦截器）

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package com.test.wangyong.remote.filter;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;

import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.extension.Activate;
import com.alibaba.dubbo.rpc.Filter;
import com.alibaba.dubbo.rpc.Invocation;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.Result;
import com.alibaba.dubbo.rpc.RpcContext;
import com.alibaba.dubbo.rpc.RpcException;
import com.test.wangyong.support.MyThreadContext;
import com.test.wangyong.support.AbstractUUIDShort;


@Activate(group = {Constants.CONSUMER, Constants.PROVIDER}, order = -30000)
public class RemoteTraceIdFilter implements Filter {
    protected final Logger log = LoggerFactory.getLogger(this.getClass());

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
       //判断是消费者  还是 服务提供者
        if (RpcContext.getContext().isConsumerSide()) {
            //消费者 将trace_id（业务流水号） set至上下文中
            RpcContext.getContext().setAttachment(MyThreadContext.TRACE_ID,
                    MyThreadContext.getTraceId());
        } else {
            //取出业务流水号
            String traceId =
                    RpcContext.getContext().getAttachment(MyThreadContext.TRACE_ID);
            if (traceId == null) {
                traceId = AbstractUUIDShort.generate();
            }
            //流水号set至线程局部变量
            MyThreadContext.setTraceId(traceId);
            //slf4j 中设置了日志打印格式用作日志链路追踪
            MDC.put(MyThreadContext.MDC_TRACE_ID, traceId);
        }
        try {
            return invoker.invoke(invocation);
        } finally {
            if (RpcContext.getContext().isProviderSide()) {
                MDC.remove(MyThreadContext.MDC_TRACE_ID);
                MyThreadContext.removeTraceId();
            }
        }
    }
}

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在resources目录下新建META-INF文件夹，然后建立子文件夹dubbo,最后新建文件com.alibaba.dubbo.rpc.Filter。（敲黑板划重点拉！这里不要弄错了）
为你的过滤器起个名并附上对应的过滤器实现类的路径，如下图就取名为traceId（这里的名大家根据业务自己起名字）

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tubeException=com.wangyong.bee.tube.dubbox.TubeExceptionFilter
tubeLog=com.wangyong.bee.tube.dubbox.TubeLogFilter
tubeContext=com.wangyong.bee.tube.dubbox.TubeContextFilter
tubeConfException=com.wangyong.bee.tube.dubbox.TubeConfExceptionFilter

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<dubbo:provider filter="traceId" />
<dubbo:consumer filter="traceId" />