在项目开发的过程中，我们常常会把一些常用的线程上下文信息放到ThreadLocal中(如Spring中的RequestContextHolder)，方便在程序中随时调取。但是在使用多线程时父线程中的ThreadLocal通常无法直接传递到子线程中去，容易造成程序bug。 这种情况通常有两种方式将父线程中的ThreadLocal传递到子线程中。
方法一
最常规的想法是在编写子线程任务时，每次都手动的将子线程需要用到的ThreadLocal数据传递到子线程中，这样子线程也能过随时获取到线程上下文信息。
方法二
自定义一个ThreadPoolExecutor代替系统的ThreadPoolExecutor，每次用线程池提交线程任务时，线程池会自动将父线程的ThreadLocal自动传递到子线程中，避免每次手动传递ThreadLocal到子线程。
代码如下所示：
public class TraceThreadPoolExecutor extends ThreadPoolExecutor {
public TraceThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
}
public TraceThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
}
public TraceThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);
}
public TraceThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
}
/**
* 覆盖execute方法,将一些上下文信息传递到子线程,如登陆用户信息等
*/
@Override
public void execute(final Runnable command) {
final LoginUser loginUser = getLoginUser();
Runnable task = new Runnable() {
@Override
public void run() {
SessionInfoContextHolder.setLoginInfo(loginUser);
try{
command.run();
} catch (Exception e){
//dosomething
} finally {
clearLoginInfo();
}
}
};
super.execute(task);
}
}
csdn博客文章地址:https://blog.csdn.net/dushenzhi/article/details/52770379
