如何获取正在运行的线程的ID？（How to get the Id of the running thread?）

问题描述 (Problem Description)

如何获取正在运行的线程的ID？

解决方案 (Solution)

下面的示例演示如何使用getThreadId（）方法获取正在运行的线程的Id。

public class Main extends Object implements Runnable {
   private ThreadID var;
   public Main(ThreadID v) {
      this.var = v;
   } 
   public void run() {
      try {
         print("var getThreadID =" + var.getThreadID());
         Thread.sleep(2000);
         print("var getThreadID =" + var.getThreadID());
      } catch (InterruptedException x) {}
   } 
   private static void print(String msg) {
      String name = Thread.currentThread().getName();
      System.out.println(name + ": " + msg);
   } 
   public static void main(String[] args) {
      ThreadID tid = new ThreadID();
      Main shared = new Main(tid);
      try {
         Thread threadA = new Thread(shared, "threadA");
         threadA.start();
         Thread.sleep(500);
         Thread threadB = new Thread(shared, "threadB");
         threadB.start();
         Thread.sleep(500);
         Thread threadC = new Thread(shared, "threadC");
         threadC.start();
      } catch (InterruptedException x) {}
   }
}
class ThreadID extends ThreadLocal {
   private int nextID;
   public ThreadID() {
      nextID = 10001;
   } 
   private synchronized Integer getNewID() {
      Integer id = new Integer(nextID);
      nextID++;
      return id;
   } 
   protected Object initialValue() {
      print("in initialValue()");
      return getNewID();
   } 
   public int getThreadID() {
      Integer id = (Integer) get();
      return id.intValue();
   } 
   private static void print(String msg) {
      String name = Thread.currentThread().getName();
      System.out.println(name + ": " + msg);
   }
}

结果 (Result)

上面的代码示例将产生以下结果。

threadA: in initialValue()
threadA: var getThreadID =10001
threadB: in initialValue()
threadB: var getThreadID =10002
threadC: in initialValue()
threadC: var getThreadID =10003
threadA: var getThreadID =10001
threadB: var getThreadID =10002
threadC: var getThreadID =10003