正文
这里详细分析interrupt(),interrupted(),isInterrupted()三个方法
interrupt()
中断这个线程,设置中断标识位
public void interrupt() { if (this != Thread.currentThread()) checkAccess(); synchronized (blockerLock) { Interruptible b = blocker; if (b != null) { interrupt0(); // Just to set the interrupt flag b.interrupt(this); return; } } interrupt0(); }
我们来找下如何设置中断标识位的
找到interrupt0()的源码,src/hotspot/share/prims/jvm.cpp
JVM_ENTRY(void, JVM_Interrupt(JNIEnv* env, jobject jthread)) ... if (is_alive) { // jthread refers to a live JavaThread. Thread::interrupt(receiver); } JVM_END
调用了Thread::interrupt方法
src/hotspot/share/runtime/thread.cpp
void Thread::interrupt(Thread* thread) { ... os::interrupt(thread); }
os::interrupt方法,src/hotspot/os/posix/os_posix.cpp
void os::interrupt(Thread* thread) { ... OSThread* osthread = thread->osthread(); if (!osthread->interrupted()) { //设置中断标识位 osthread->set_interrupted(true); ... } ... }
isInterrupted()
测试线程是否被中断,线程的中断状态不会改变
public boolean isInterrupted() { return isInterrupted(false); }
查看native isInterrupted(boolean ClearInterrupted)源码,查找方式同上
src/hotspot/os/posix/os_posix.cpp
bool os::is_interrupted(Thread* thread, bool clear_interrupted) { debug_only(Thread::check_for_dangling_thread_pointer(thread);) OSThread* osthread = thread->osthread(); // 查看是否被中断 bool interrupted = osthread->interrupted(); // 清除标识位后再设置false if (interrupted && clear_interrupted) { osthread->set_interrupted(false); } return interrupted; }
Java传递ClearInterrupted为false,对应C++的clear_interrupted
interrupted()
测试线程是否被中断,清除中断标识位
public static boolean interrupted() { return currentThread().isInterrupted(true); }
简单的例子
public class MyThread45 { public static void main(String[] args) throws Exception { Runnable runnable = new Runnable() { public void run() { while (true) { if (Thread.currentThread().isInterrupted()) { System.out.println("线程被中断了"); return ; } else { System.out.println("线程没有被中断"); } } } }; Thread t = new Thread(runnable); t.start(); Thread.sleep(500); t.interrupt(); System.out.println("线程中断了,程序到这里了"); } }
检查线程是否中断,中断线程,运行结果如下
······ 线程没有被中断 线程没有被中断 线程没有被中断 线程被中断了 线程中断了,程序到这里了
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