Java多线程:线程死锁

package basic.e_deadlock;

import org.apache.log4j.Logger;

public class TestDeadLock {
public static void main(String[] args) {
DeadlockRisk dead = new DeadlockRisk();
MyThread t1 = new MyThread(dead, 1, 2, "线程1");
MyThread t2 = new MyThread(dead, 3, 4, "线程2");
MyThread t3 = new MyThread(dead, 5, 6, "线程3");
MyThread t4 = new MyThread(dead, 7, 8, "线程4");
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, String threadName) {
this.dead = dead;
this.a = a;
this.b = b;
this.setName(threadName);
}

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

class DeadlockRisk {
private static Logger logger = Logger.getLogger(DeadlockRisk.class);
private static class Resource {
public int value;
}

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

public void read() {
logger.debug("===========read  begin===========");
synchronized (resourceA) {
logger.debug("read():" + Thread.currentThread().getName() + "获取了resourceA 的锁！");
synchronized (resourceB) {
logger.debug("read():" + Thread.currentThread().getName() + "获取了resourceB 的锁！");
}
}
logger.debug("===========read  end=============");
}

public void write(int a, int b) {
logger.debug("===========write begin===========");
synchronized (resourceB) {
logger.debug("write():" + Thread.currentThread().getName() + "获取了resourceB 的锁！");
synchronized (resourceA) {
logger.debug("write():" + Thread.currentThread().getName() + "获取了resourceA 的锁！");
resourceA.value = a;
resourceB.value = b;
}
}
logger.debug("===========write end=============");
}
}

0    [线程1] DEBUG basic.e_deadlock.DeadlockRisk - ===========read  begin===========
0    [线程2] DEBUG basic.e_deadlock.DeadlockRisk - ===========read  begin===========
0    [线程4] DEBUG basic.e_deadlock.DeadlockRisk - ===========read  begin===========
0    [线程3] DEBUG basic.e_deadlock.DeadlockRisk - ===========read  begin===========
0    [线程1] DEBUG basic.e_deadlock.DeadlockRisk - read():线程1获取了resourceA 的锁！
0    [线程1] DEBUG basic.e_deadlock.DeadlockRisk - read():线程1获取了resourceB 的锁！
0    [线程1] DEBUG basic.e_deadlock.DeadlockRisk - ===========read  end=============
0    [线程2] DEBUG basic.e_deadlock.DeadlockRisk - read():线程2获取了resourceA 的锁！
0    [线程1] DEBUG basic.e_deadlock.DeadlockRisk - ===========write being===========
1    [线程2] DEBUG basic.e_deadlock.DeadlockRisk - read():线程2获取了resourceB 的锁！
1    [线程2] DEBUG basic.e_deadlock.DeadlockRisk - ===========read  end=============
1    [线程2] DEBUG basic.e_deadlock.DeadlockRisk - ===========write being===========
1    [线程1] DEBUG basic.e_deadlock.DeadlockRisk - write():线程1获取了resourceB 的锁！
1    [线程4] DEBUG basic.e_deadlock.DeadlockRisk - read():线程4获取了resourceA 的锁！