系统中有自己的Netty服务器，同时指定Dubbo用Netty，然后LoggingHandler就没法用了。下面的代码回导致我的Netty服务器无法使用Netty自带的日志体系。如果我强制自己的Netty服务器晚于Dubbo加载，那么Dubbo也是无法使用到DubboLogger的。
```
public class NettyHelper {

    public static void setNettyLoggerFactory() {
        InternalLoggerFactory factory = InternalLoggerFactory.getDefaultFactory();
        if (factory == null || !(factory instanceof DubboLoggerFactory)) {
            InternalLoggerFactory.setDefaultFactory(new DubboLoggerFactory());
        }
    }
```
# Added content in English. Help with Google Translate
System is TCP server using Netty4, and Dubbo is specified to use Netty4. When I add LoggingHandler to ChannelPipeline of my System, The log is not expected. 
Like this:
![image](https://user-images.githubusercontent.com/11850956/37442060-5a02eabc-283f-11e8-939a-68255f8912b2.png)

I tracked the code and found the Logger is `com.alibaba.dubbo.remoting.transport.netty4.logging.NettyHelper.DubboLogger` instead of `io.netty.util.internal.logging.Slf4JLogger`.  DubboLogger added other content arount the original log. The NeetyHelper replace the InternalLoggerFactory when Dubbo loading, like the code block above shows.
# By the way.
My system build by Spring Boot, use default logging framework which is Slf4j + Logback.
Dubbo's logger is not extend default logger, but replace it.
![image](https://user-images.githubusercontent.com/11850956/37442386-0585c494-2841-11e8-8f8f-354e7f226726.png)

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 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
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package com.alibaba.dubbo.remoting.transport.netty4;
import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.Version;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.common.utils.NetUtils;
import com.alibaba.dubbo.remoting.ChannelHandler;
import com.alibaba.dubbo.remoting.RemotingException;
import com.alibaba.dubbo.remoting.transport.AbstractClient;
import com.alibaba.dubbo.remoting.transport.netty4.logging.NettyHelper;
import io.netty.bootstrap.Bootstrap;