Java 获取线程的 ID

Main.java 文件

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);
  }
}

以上代码运行输出结果为：

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