如何實現自定義同步組件

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();                }            }        }    }}
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