log4j 同一线程隔离classloader下MDC信息不同问题解决 ThreadLocal问题分析

package com.coderli.log4j.mdc;


import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;


import org.apache.log4j.MDC;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
* 单线程多 classloader模式下，log4jMDC信息传递测试。
*
* @author OneCoder
* @blog http://www.coderli.com
* @date 2014年5月6日 上午10:55:34
*/
public class SingleThreadMultiLoader {


     private static final Logger logger = LoggerFactory
              . getLogger(SingleThreadMultiLoader.class);
     private static String key = "loaderName";
     static ThreadLocal<String> tl = new ThreadLocal<String>();


     public static void main(String[] args) throws MalformedURLException,
              ClassNotFoundException, InstantiationException,
              IllegalAccessException, NoSuchMethodException, SecurityException,
              IllegalArgumentException, InvocationTargetException {
          MDC. put(key, "in main loader" );
           logger.info( "线程名: {}; 日志MDC信息：{}。" , Thread.currentThread().getName(),
                   MDC. get(key));
           tl.set( "huanyige");
          ClassLoader cLoader = Thread.currentThread().getContextClassLoader();
          URL[] urls = new URL[] {
                    new URL("file:\\D:\\acap\\workspace\\shurnim-lab\\lib\\mdc.jar" ),
                    new URL(
                              "file:\\D:\\acap\\workspace\\shurnim-lab\\lib\\log4j-1.2.17.jar" ),
                    new URL(
                              "file:\\D:\\acap\\workspace\\shurnim-lab\\lib\\slf4j-api-1.7.5.jar" ),
                    new URL(
                              "file:\\D:\\acap\\workspace\\shurnim-lab\\lib\\slf4j-log4j12-1.7.5.jar" ) };
          ClassLoader loader = new URLClassLoader(urls, null);
          Thread. currentThread().setContextClassLoader(loader);
          String className = SingleThreadMultiLoader.class.getName();
           Class clz = loader.loadClass(className);
          Method main = clz.getMethod("logMethod");
          main.invoke( null);
           logger.info( "线程名: {}; 日志MDC信息：{}。" , Thread.currentThread().getName(),
                   MDC. get(key));
     }


     public static void logMethod() {
           logger.info( "线程名: {}; 日志MDC信息：{}。" , Thread.currentThread().getName(),
                   MDC. get(key));
          MDC. put(key, "hahahahhaha" );
          System. out.println( tl.get());
     }
}

public T get() {
        Thread t = Thread.currentThread();
        ThreadLocalMap map = getMap(t);
        if (map != null) {
            ThreadLocalMap.Entry e = map.getEntry(this);
            if (e != null)
                return (T)e.value;
        }
        return setInitialValue();
    }