Java中死锁的原理实战分析

class A
{
   public synchronized void foo( B b )
   {
      System.out.println("当前线程名: " + Thread.currentThread().getName()
        + " 进入了A实例的foo()方法" );   // ①
      try
      {
        Thread.sleep(200);
      }
      catch (InterruptedException ex)
      {
        ex.printStackTrace();
      }
      System.out.println("当前线程名: " + Thread.currentThread().getName()
        + " 企图调用B实例的last()方法");  // ③
      b.last();
   }
   public synchronized void last()
   {
      System.out.println("进入了A类的last()方法内部");
   }
}
class B
{
   public synchronized void bar( A a )
   {
      System.out.println("当前线程名: " + Thread.currentThread().getName()
        + " 进入了B实例的bar()方法" );  // ②
      try
      {
        Thread.sleep(200);
      }
      catch (InterruptedException ex)
      {
        ex.printStackTrace();
      }
      System.out.println("当前线程名: " + Thread.currentThread().getName()
        + " 企图调用A实例的last()方法"); // ④
      a.last();
   }
   public synchronized void last()
   {
      System.out.println("进入了B类的last()方法内部");
   }
}
public class DeadLock implements Runnable
{
   A a = new A();
   B b = new B();
   public void init()
   {
      Thread.currentThread().setName("主线程");
      // 调用a对象的foo方法
      a.foo(b);
      System.out.println("进入了主线程之后");
   }
   public void run()
   {
      Thread.currentThread().setName("副线程");
      // 调用b对象的bar方法
      b.bar(a);
      System.out.println("进入了副线程之后");
   }
   public static void main(String[] args)
   {
      DeadLock dl = new DeadLock();
      // 以dl为target启动新线程
      new Thread(dl).start();
      // 调用init()方法
      dl.init();
   }
}