按我的理解，當(dāng)一個(gè)線程需要獲取的鎖被另一個(gè)線程占用時(shí)，將進(jìn)入阻塞態(tài)。但實(shí)際好像不是這樣的，下面是我的代碼。在run方法中會(huì)調(diào)用MyBlock的isBlocked方法，該方法添加了synchronized限定。在main方法中創(chuàng)建兩個(gè)線程：t1和t2，t1運(yùn)行后，由于isBlocked方法運(yùn)行需要一定時(shí)間，t2應(yīng)該進(jìn)入阻塞態(tài)。但我調(diào)用getState方法得到的是Runnable，不是Blocked。這是為啥呢？ public class TestThread implements Runnable {
private String mThreadName = null;
private MyLock mLock = null;
public TestThread(String name, MyLock l){
mThreadName = name;
mLock = l;
}
@Override
public void run() {
// TODO Auto-generated method stub
subTask();
}
private void subTask()
{
System.out.println(mThreadName + "START!");
mLock.isLocked();
System.out.println(mThreadName + "END!");
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
MyLock lock = new MyLock();
TestThread r1 = new TestThread("A", lock);
Thread t1 = new Thread(r1);
t1.start();
TestThread r2 = new TestThread("B", lock);
Thread t2 = new Thread(r2);
t2.start();
System.out.println(t2.getState());
//t2.interrupt();
System.out.println(t2.getState());
System.out.println("MAIN END!");
}
public static class MyLock{
private ReentrantLock mLock = new ReentrantLock();
public synchronized void isLocked(){
System.out.println("@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
for (int i = 0; i < 10000; i ++){
System.out.print("," + i);
}
System.out.println("#############################");
}
}
}
5 回答
茅侃侃
TA貢獻(xiàn)1842條經(jīng)驗(yàn) 獲得超21個(gè)贊
private ReentrantLock mLock = new ReentrantLock();
還可以用mLock通過(guò)trylock和lock去在臨界區(qū)枷鎖測(cè)試。
白板的微信
TA貢獻(xiàn)1883條經(jīng)驗(yàn) 獲得超3個(gè)贊
package iteye;
public class TestThread implements Runnable {
private final String mThreadName;
private final MyLock mLock;
public TestThread(String name, MyLock l) {
mThreadName = name;
mLock = l;
}
public void run() {
System.out.println(mThreadName + " START!");
mLock.lock();
System.out.println(mThreadName + " END!");
}
/**
* @param args
*/
public static void main(String[] args) {
MyLock lock = new MyLock();
TestThread r1 = new TestThread("A", lock);
Thread t1 = new Thread(r1);
t1.start();
// 確保t1先進(jìn)入run方法
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
TestThread r2 = new TestThread("B", lock);
Thread t2 = new Thread(r2);
t2.start();
// 確保t2進(jìn)入run方法
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
// 只有t1正在執(zhí)行l(wèi)ock方法中，而t2也進(jìn)入run方法等待執(zhí)行l(wèi)ock方法時(shí)，t2的狀態(tài)才是BLOCKED
System.out.println(t2.getState());
System.out.println("MAIN END!");
}
public static class MyLock {
public synchronized void lock() {
try {
Thread.sleep(7000);//模擬線程的執(zhí)行時(shí)間比較長(zhǎng)
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}}
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