简言Java里面的Thread
关于线程的中断机制
要使任务和线程能安全，快速，可靠地停止下来，并不是一件容易的事。Java没有提供任何机制来安全地终止线程，那么我们又该如何使用线程的停止或者中断呢？
public class ThreadnterruptDemo implements Runnable {
public static void main(String[] args)throws Exception{
Thread thread=new Thread(new ThreadnterruptDemo(),"InterruptDemo Thread");
System.out.println("Starting thread...");
thread.start();
Thread.sleep(3000);
thread.interrupt();
System.out.println("线程是否中断："+thread.isInterrupted());
Thread.sleep(3000);
System.out.println("Stopping application...");
}
@Override
public void run() {
// TODO Auto-generated method stub
boolean stop=false;
while(!stop) {
System.out.println("My Thread is running...");
long time=System.currentTimeMillis();
while((System.currentTimeMillis()-time)<1000) {
}
}
System.out.println("My Thread existing under request...");
}
}
运行结果如下：
........................
if(Thread.currentThread().isInterrupted()){
//需要线程本身去处理一下它的终止状态
bread;
}
代码变成了如下：
public void run() {
// TODO Auto-generated method stub
boolean stop=false;
while(!stop) {
System.out.println("My Thread is running...");
long time=System.currentTimeMillis();
while((System.currentTimeMillis()-time)<1000) {
}
if(Thread.currentThread().isInterrupted()){
//需要线程本身去处理一下它的终止状态
break;
}
}
System.out.println("My Thread existing under request...");
}
运行结果如下：
}
线程的生命周期
什么是守护线程
public class ThreadA extends Thread {
@Override
public void run() {
// TODO Auto-generated method stub
for(long i=0;i<9999999L;i++) {
System.out.print("后台线程A第"+i+"次执行！");
try {
Thread.sleep(7);
}catch(InterruptedException e) {
e.printStackTrace();
}
}
}
}
public class ThreadB extends Thread {
public void run() {
for(int i=0;i<5;i++) {
System.out.println("线程B第"+i+"次执行！");
try {
Thread.sleep(7);
}catch(InterruptedException e) {
e.printStackTrace();
}
}
}
}
public class ThreadMain {
public static void main(String[] args) {
Thread tA=new ThreadA();
Thread tB=new ThreadB();
tA.setDaemon(true);
tB.start();
tA.start();
Thread mainThread=Thread.currentThread();
System.out.println("线程A是不是守护线程"+tA.isDaemon());
System.out.println("线程B是不是守护线程"+tB.isDaemon());
System.out.println("线程main是不是守护线程"+mainThread.isDaemon());
}
}
运行结果如下：
线程组
当前线程副本：ThreadLocal
public class ThreadMain1 {
private static ThreadLocal<Integer> seqNum=new ThreadLocal<Integer>() {
public Integer initialValue() {
return 0;
}
};
public ThreadLocal<Integer> getThreadLocal(){
return seqNum;
}
public int getNextNum() {
seqNum.set(seqNum.get()+1);
return seqNum.get();
}
public static void main(String[] args) {
ThreadMain1 sn=new ThreadMain1();
TestClient t1=new TestClient(sn);
TestClient t2=new TestClient(sn);
TestClient t3=new TestClient(sn);
t1.start();
t2.start();
t3.start();
}
private static class TestClient extends Thread{
private ThreadMain1 sn;
public TestClient(ThreadMain1 sn) {
this.sn=sn;
}
public void run() {
for(int i=0;i<3;i++) {
System.out.println("thread["+Thread.currentThread().getName()+"]-->sn"+sn.getNextNum()+"]");
}
sn.getThreadLocal().remove();
}
}
}
线程异常的处理
下面，我们就按照这个步骤来实现一个实例。
首先是实现UncaughtExceptionHandler接口部分：
import java.lang.Thread.UncaughtExceptionHandler;
public class ExceptionHandlerThreadB implements UncaughtExceptionHandler {
@Override
public void uncaughtException(Thread t, Throwable e) {
// TODO Auto-generated method stub
System.out.printf("An exception has been captured\n");
System.out.printf("Thread:%s\n",t.getId());
System.out.printf("Exception:%s:%s\n", e.getClass().getName(),e.getMessage());
System.out.printf("Stack Trace:\n");
e.printStackTrace(System.out);
System.out.printf("Thread status:%s\n",t.getState());
}
}
public class ThreadB1 implements Runnable {
@Override
public void run() {
// TODO Auto-generated method stub
int number0=Integer.parseInt("TTT");
}
}
public class ThreadMain2 {
public static void main(String[] args) {
ThreadB1 task=new ThreadB1();
Thread thread=new Thread(task);
thread.setUncaughtExceptionHandler(new ExceptionHandlerThreadB());
thread.start();
}
}
运行结果如下：