/**
* Java線程：并發協作-死鎖
*
* @author Administrator 2009-11-4 22:06:13
*/
public class Test {
???????? public static void main(String[] args) {
????????????????DeadlockRisk dead = new DeadlockRisk();
????????????????MyThread t1 = new MyThread(dead, 1, 2);
????????????????MyThread t2 = new MyThread(dead, 3, 4);
????????????????MyThread t3 = new MyThread(dead, 5, 6);
????????????????MyThread t4 = new MyThread(dead, 7, 8);

????????????????t1.start();
????????????????t2.start();
????????????????t3.start();
????????????????t4.start();
????????}

}

class MyThread extends Thread {
???????? private DeadlockRisk dead;
???????? private int a, b;


????????MyThread(DeadlockRisk dead, int a, int b) {
???????????????? this .dead = dead;
???????????????? this .a = a;
???????????????? this .b = b;
????????}

????????@Override
???????? public void run() {
????????????????dead.read();
????????????????dead.write(a, b);
????????}
}

class DeadlockRisk {
???????? private static class Resource {
???????????????? public int value;
????????}

???????? private Resource resourceA = new Resource();
???????? private Resource resourceB = new Resource();

???????? public int read() {
???????????????? synchronized (resourceA) {
????????????????????????System.out.println( "read():" + Thread.currentThread().getName() + "獲取了resourceA的鎖！" );
???????????????????????? synchronized (resourceB) {
????????????????????????????????System.out.println( "read():" + Thread.currentThread().getName() + "獲取了resourceB的鎖！" );
???????????????????????????????? return resourceB.value + resourceA.value;
????????????????????????}
????????????????}
????????}

???????? public void write( int a, int b) {
???????????????? synchronized (resourceB) {
????????????????????????System.out.println( "write():" + Thread.currentThread().getName() + "獲取了resourceA的鎖！" );
???????????????????????? synchronized (resourceA) {
????????????????????????????????System.out.println( "write():" + Thread.currentThread().getName() + "獲取了resourceB的鎖！" );
????????????????????????????????resourceA.value = a;
????????????????????????????????resourceB.value = b;
????????????????????????}
????????????????}
????????}
}