多线程之同步Synchronized

标签：多线程   同步   synchronized   

在java中synchronized是多个线程共享同一段代码的锁。

当有多个线程并发执行同一块代码块时，加锁可以让一段时间内只有一个线程在执行，保证了业务的原子操作。

例如下面：

package andy.thread.traditional.test;

/**
 * @author Zhang,Tianyou
 * @version 2014年11月8日 下午11:02:53
 */

// 使用synchronized加同步锁

public class ThreadSynchronizedTest {

	public static void main(String[] args) {
		A a = new A();

		new Thread(new Runnable() {

			@Override
			public void run() {
				while (true) {
					try {
						Thread.sleep(10);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}

					a.printfA(Thread.currentThread().getName()
							+ "hello, my is A");
				}

			}
		}).start();

		new Thread(new Runnable() {

			@Override
			public void run() {
				while (true) {
					try {
						Thread.sleep(10);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}

					a.printfA(Thread.currentThread().getName()
							+ "hello, my is B");
				}

			}
		}).start();

	}

	static class A {
		public void printfA(String name) {

			for (int i = 0; i < name.length(); i++) {
				System.out.print(name.charAt(i));
			}

			System.out.println();

		}


	}

}

Thread-1hello, my is B
Thread-1hello, my is B
Thread-0hello, my is A
ThThread-0hello, my is A
read-1hello, my is B
Thread-1helTlhreoad-0hello, my is A
, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A

synchronized（name）{

// 加锁的代码块， name为锁标志

}

syschronized 可以加在方法里和方法内：

package andy.thread.traditional.test;

/**
 * @author Zhang,Tianyou
 * @version 2014年11月8日 下午11:02:53
 */

// 使用synchronized加同步锁

public class ThreadSynchronizedTest {

	public static void main(String[] args) {
		A a = new A();

		new Thread(new Runnable() {

			@Override
			public void run() {
				while (true) {
					try {
						Thread.sleep(10);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}

					a.printfA(Thread.currentThread().getName()
							+ "hello, my is A");
				}

			}
		}).start();

		new Thread(new Runnable() {

			@Override
			public void run() {
				while (true) {
					try {
						Thread.sleep(10);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}

					a.printfA(Thread.currentThread().getName()
							+ "hello, my is B");
				}

			}
		}).start();

	}

	static class A {
		public  void printfA(String name) {

			synchronized (A.class) {
				for (int i = 0; i < name.length(); i++) {
					System.out.print(name.charAt(i));
				}

				System.out.println();
			}
			

		}

		public synchronized void printfB(String name) {

			for (int i = 0; i < name.length(); i++) {
				System.out.print(name.charAt(i));
			}

			System.out.println();

		}
	}

}

运行效果如下：

Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B
Thread-0hello, my is A
Thread-1hello, my is B

多线程之同步Synchronized

标签：多线程   同步   synchronized   

原文地址：http://blog.csdn.net/fengshizty/article/details/40931685