lock--unlock的方式在实际中使用较少，一般使用synchronized获取对象的内部锁替代，但是lock--unlock对了解synchronized有很大的帮助。
创建一个bank对象用于模拟动作
package reentrant_lock; import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock; /**
* Created by luozhitao on 2017/8/18.
*/
public class Bank { private final double[] accounts;
private Lock bankLock;
private Condition newCondition; public Bank(int n,double intialBalance){ accounts=new double[n]; for(int i =;i<n;i++){
accounts[i]=intialBalance;
} bankLock=new ReentrantLock();
newCondition=bankLock.newCondition(); } //
public void tansfer(int from,int to,double account_m) throws InterruptedException{ bankLock.lock();
int aa=; try{ while (accounts[from]<account_m) {
System.out.println(Thread.currentThread()+"被阻塞");
aa++;
newCondition.await();
} if(aa>) {
System.out.println(Thread.currentThread()+"从阻塞状态被唤醒");
aa=; } accounts[from]-=account_m; System.out.printf("%10.2f from %d to %d",account_m,from,to); accounts[to]+=account_m;
System.out.println("-----");
System.out.printf("the total banlance %10.2f", getTotal()); System.out.println("释放transfer锁之前");
//newCondition.notifyAll();
newCondition.signalAll();
System.out.println("释放transfer锁之后"); } finally { bankLock.unlock(); } } //
public double getTotal(){ bankLock.lock();
try{
double sum=;
for(double a:accounts){ sum+=a;
} return sum; }finally {
bankLock.unlock(); } } // public int size(){ return accounts.length;
}
}
创建线程
package reentrant_lock; /**
* Created by luozhitao on 2017/8/18.
*/
public class transferRunnable implements Runnable { private Bank bank;
private int fromAccount;
private double maxAccount;
private int DELAY=;
int flag=; public transferRunnable(Bank b,int from,double max){
this.bank=b;
this.fromAccount=from;
this.maxAccount=max; } public void run() { try{
while (true){
int toAccount=(int)((bank.size()-)*Math.random()); System.out.println("toAccount ="+toAccount);
double account_m=maxAccount*Math.random();
System.out.println("account_m is "+account_m);
bank.tansfer(fromAccount,toAccount,account_m); Thread.sleep((int) (DELAY * Math.random()));
flag++; }
}catch (InterruptedException e){e.printStackTrace();} }
}
main
package reentrant_lock; /**
* Created by luozhitao on 2017/8/18.
*/
public class Banktest { private static final int Naccount=;
private static final double inital_balance=; public static void main(String [] args){ Bank b=new Bank(Naccount,inital_balance); for(int i=;i<;i++){ transferRunnable t=new transferRunnable(b,i,inital_balance); Thread thread=new Thread(t);
thread.start(); } } }