浅谈多线程中的锁的几种用法总结(必看)

一、ReentrantLock

package com.ietree.basicskill.mutilthread.lock;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


public class UseReentrantLock {

  private Lock lock = new ReentrantLock();

  public void method1(){
    try {
      lock.lock();
      System.out.println("当前线程:" + Thread.currentThread().getName() + "进入method1..");
      Thread.sleep(1000);
      System.out.println("当前线程:" + Thread.currentThread().getName() + "退出method1..");
      Thread.sleep(1000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    } finally {

      lock.unlock();
    }
  }

  public void method2(){
    try {
      lock.lock();
      System.out.println("当前线程:" + Thread.currentThread().getName() + "进入method2..");
      Thread.sleep(2000);
      System.out.println("当前线程:" + Thread.currentThread().getName() + "退出method2..");
      Thread.sleep(1000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    } finally {

      lock.unlock();
    }
  }

  public static void main(String[] args) {

    final UseReentrantLock ur = new UseReentrantLock();
    Thread t1 = new Thread(new Runnable() {
      @Override
      public void run() {
 ur.method1();
 ur.method2();
      }
    }, "t1");

    t1.start();
    try {
      Thread.sleep(10);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    //System.out.println(ur.lock.getQueueLength());
  }

}

二、ReentrantReadWriteLock

package com.ietree.basicskill.mutilthread.lock;

import java.util.concurrent.locks.ReentrantReadWriteLock;


public class UseReentrantReadWriteLock {

  private ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();
  private ReentrantReadWriteLock.ReadLock readLock = rwLock.readLock();
  private ReentrantReadWriteLock.WriteLock writeLock = rwLock.writeLock();

  public void read(){
    try {
      readLock.lock();
      System.out.println("当前线程:" + Thread.currentThread().getName() + "进入...");
      Thread.sleep(3000);
      System.out.println("当前线程:" + Thread.currentThread().getName() + "退出...");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      readLock.unlock();
    }
  }

  public void write(){
    try {
      writeLock.lock();
      System.out.println("当前线程:" + Thread.currentThread().getName() + "进入...");
      Thread.sleep(3000);
      System.out.println("当前线程:" + Thread.currentThread().getName() + "退出...");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      writeLock.unlock();
    }
  }

  public static void main(String[] args) {

    final UseReentrantReadWriteLock urrw = new UseReentrantReadWriteLock();

    Thread t1 = new Thread(new Runnable() {
      @Override
      public void run() {
 urrw.read();
      }
    }, "t1");
    Thread t2 = new Thread(new Runnable() {
      @Override
      public void run() {
 urrw.read();
      }
    }, "t2");
    Thread t3 = new Thread(new Runnable() {
      @Override
      public void run() {
 urrw.write();
      }
    }, "t3");
    Thread t4 = new Thread(new Runnable() {
      @Override
      public void run() {
 urrw.write();
      }
    }, "t4");

//    t1.start();
//    t2.start();

//    t1.start(); // R
//    t3.start(); // W

    t3.start();
    t4.start();
  }
}

三、Condition

package com.ietree.basicskill.mutilthread.lock;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


public class UseCondition {
  private Lock lock = new ReentrantLock();
  private Condition condition = lock.newCondition();

  public void method1(){
    try {
      lock.lock();
      System.out.println("当前线程：" + Thread.currentThread().getName() + "进入等待状态..");
      Thread.sleep(3000);
      System.out.println("当前线程：" + Thread.currentThread().getName() + "释放锁..");
      condition.await();  // Object wait
      System.out.println("当前线程：" + Thread.currentThread().getName() +"继续执行...");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public void method2(){
    try {
      lock.lock();
      System.out.println("当前线程：" + Thread.currentThread().getName() + "进入..");
      Thread.sleep(3000);
      System.out.println("当前线程：" + Thread.currentThread().getName() + "发出唤醒..");
      condition.signal();    //Object notify
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public static void main(String[] args) {

    final UseCondition uc = new UseCondition();
    Thread t1 = new Thread(new Runnable() {
      @Override
      public void run() {
 uc.method1();
      }
    }, "t1");
    Thread t2 = new Thread(new Runnable() {
      @Override
      public void run() {
 uc.method2();
      }
    }, "t2");
    t1.start();

    t2.start();
  }
}

四、ManyCondition

package com.ietree.basicskill.mutilthread.lock;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;


public class UseManyCondition {
  private ReentrantLock lock = new ReentrantLock();
  private Condition c1 = lock.newCondition();
  private Condition c2 = lock.newCondition();

  public void m1(){
    try {
      lock.lock();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "进入方法m1等待..");
      c1.await();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "方法m1继续..");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public void m2(){
    try {
      lock.lock();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "进入方法m2等待..");
      c1.await();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "方法m2继续..");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public void m3(){
    try {
      lock.lock();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "进入方法m3等待..");
      c2.await();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "方法m3继续..");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public void m4(){
    try {
      lock.lock();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "唤醒..");
      c1.signalAll();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public void m5(){
    try {
      lock.lock();
      System.out.println("当前线程：" +Thread.currentThread().getName() + "唤醒..");
      c2.signal();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      lock.unlock();
    }
  }

  public static void main(String[] args) {


    final UseManyCondition umc = new UseManyCondition();
    Thread t1 = new Thread(new Runnable() {
      @Override
      public void run() {
 umc.m1();
      }
    },"t1");
    Thread t2 = new Thread(new Runnable() {
      @Override
      public void run() {
 umc.m2();
      }
    },"t2");
    Thread t3 = new Thread(new Runnable() {
      @Override
      public void run() {
 umc.m3();
      }
    },"t3");
    Thread t4 = new Thread(new Runnable() {
      @Override
      public void run() {
 umc.m4();
      }
    },"t4");
    Thread t5 = new Thread(new Runnable() {
      @Override
      public void run() {
 umc.m5();
      }
    },"t5");

    t1.start();  // c1
    t2.start();  // c1
    t3.start();  // c2


    try {
      Thread.sleep(2000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }

    t4.start();  // c1
    try {
      Thread.sleep(2000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    t5.start();  // c2

  }
}

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