package com.chen;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
/**
* desc:自定義同步組件,只容許最多n個線程同時訪問
* // 1.共享訪問
* // 2.定義n個資源數
* Created by chenjianye on 2017/5/26.
*/
public class ServerLock implements Lock{
private Sync sync = null;
public ServerLock(int ServerLockNum) {
this.sync = new Sync(ServerLockNum);
}
private final class Sync extends AbstractQueuedSynchronizer {
Sync(int count){
setState(count);
}
public int tryAcquireShared(int reduceCount) {
for(;;) {
int current = getState();
int newCount = current - reduceCount;
if (newCount < 0 || compareAndSetState(current, newCount)) {
return newCount;
}
}
}
public boolean tryReleaseShared(int returnCount) {
for(;;) {
int current = getState();
int newCount = current + returnCount;
if (compareAndSetState(current, newCount)) {
return true;
}
}
}
}
@Override
public void lock() {
// sync.acquire(1);
sync.acquireShared(1);
}
@Override
public void unlock() {
sync.releaseShared(1);
}
@Override
public void lockInterruptibly() throws InterruptedException {
System.out.println("dd");
}
@Override
public boolean tryLock() {
return false;
}
@Override
public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
return sync.tryAcquireNanos(1, unit.toNanos(1000));
}
@Override
public Condition newCondition() {
throw new RuntimeException("");
}
}
package com.chen;import java.util.concurrent.locks.Lock;/** * desc:測試自定義鎖 * Created by chenjianye on 2017/5/26. */public class TestLock { public static void main(String[] args) { ServerLock lock = new ServerLock(4);// ReentrantReadWriteLock lock = new ReentrantReadWriteLock();// Lock tmp = lock.writeLock(); for(int i=0;i<20;i++) { Worker worker = new Worker(lock); worker.start(); } } static class Worker extends Thread{ Lock lock; Worker(Lock lock) { this.lock = lock; } public void run() { while (true) { lock.lock(); try{ Thread.sleep(1000); System.out.println("Thread name:" + Thread.currentThread().getName()+"時間:"+System.currentTimeMillis()/1000); } catch (InterruptedException e) { e.printStackTrace(); } finally { lock.unlock(); } } } }}