之前对interrupt()方法一直不太理解,可能是这个名字太具有迷惑性了吧。
interrupt不能中断正在运行的线程,如下代码
class Example1 extends Thread { boolean stop = false; public static void main(String args[]) throws Exception { Example1 thread = new Example1(); System.out.println("Starting thread..."); thread.start(); Thread.sleep(3000); System.out.println("Interrupting thread..."); thread.interrupt(); System.out.println("thread interrupt()" + thread.isInterrupted()); Thread.sleep(3000); System.out.println("Stopping application..."); // System.exit(0); } public void run() { while (!stop) { System.out.println("Thread is running..."); long time = System.currentTimeMillis(); while ((System.currentTimeMillis() - time < 1000)) { } } System.out.println("Thread exiting under request..."); } }
但是上面的代码还是有漏洞的,Example1对thread执行了interrupt操作,没有中断thread是因为interrupt方法只是在目标线程中设置了一个标志,表示它已经被中断。Example1对thread设置了中断标志但并没有检查这个标志是否被设置,所以Example1无法中断thread。对上面代码修改如下
class Example1 extends Thread { boolean stop = false; public static void main(String args[]) throws Exception { Example1 thread = new Example1(); System.out.println("Starting thread..."); thread.start(); Thread.sleep(3000); System.out.println("Interrupting thread..."); thread.interrupt(); System.out.println("thread interrupt()" + thread.isInterrupted()); Thread.sleep(3000); System.out.println("Stopping application..."); // System.exit(0); } public void run() { //检查中断标志 while (!stop && !Thread.currentThread().isInterrupted()) { System.out.println("Thread is running..."); long time = System.currentTimeMillis(); while ((System.currentTimeMillis() - time < 1000)) { } } System.out.println("Thread exiting under request..."); } }