多线程编程

code/Java/java-concurrency/src/main/java/com/heibaiying/readWriteLock/ReadWriteLock.java

@@ -0,0 +1,94 @@
+package com.heibaiying.readWriteLock;
+
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+public class ReadWriteLock {
+
+	// 可重入锁
+	private static ReentrantLock reentrantLock = new ReentrantLock();
+	// 读写锁
+	private static ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
+	// 读锁
+	private static ReentrantReadWriteLock.ReadLock readLock = readWriteLock.readLock();
+	// 写锁
+	private static ReentrantReadWriteLock.WriteLock writeLock = readWriteLock.writeLock();
+
+	// 待赋值的变量
+	private static String i = "";
+
+	//写方法
+	static class Write implements Runnable {
+
+		private Lock lock;
+		private String value;
+
+		Write(Lock lock, String value) {
+			this.lock = lock;
+			this.value = value;
+		}
+
+		@Override
+		public void run() {
+			try {
+				lock.lock();
+				Thread.sleep(1000);
+				i = value;
+				System.out.println(Thread.currentThread().getName() + "写入值" + i);
+			} catch (InterruptedException e) {
+				e.printStackTrace();
+			} finally {
+				lock.unlock();
+			}
+		}
+	}
+
+	//读方法
+	static class Read implements Runnable {
+
+		private Lock lock;
+
+		Read(Lock lock) {
+			this.lock = lock;
+		}
+
+		@Override
+		public void run() {
+			try {
+				lock.lock();
+				Thread.sleep(1000);
+				System.out.println(Thread.currentThread().getName() + "读取到值" + i);
+			} catch (InterruptedException e) {
+				e.printStackTrace();
+			} finally {
+				lock.unlock();
+			}
+		}
+	}
+
+
+	public static void main(String[] args) throws InterruptedException {
+
+		// 耗时2秒，写锁是互斥的，但读锁是并行的
+		for (int j = 0; j < 2; j++) {
+			Thread thread = new Thread(new Write(writeLock, String.valueOf(j)));
+			thread.start();
+		}
+		for (int j = 0; j < 18; j++) {
+			Thread thread = new Thread(new Read(readLock));
+			thread.start();
+		}
+
+
+		// 使用重入锁时，读锁彼此之间也是互斥的
+		for (int j = 0; j < 2; j++) {
+			Thread thread = new Thread(new Write(reentrantLock, String.valueOf(j)));
+			thread.start();
+		}
+		for (int j = 0; j < 18; j++) {
+			Thread thread = new Thread(new Read(reentrantLock));
+			thread.start();
+		}
+	}
+}