之前我们使用多线程要么是继承​​Thread​​​类，要么是实现​​Runnable​​​接口，然后重写一下​​run()​​方法即可。

但是只有的话如果有死锁、对共享资源的访问和随时监控线程状态就不行了，于是在Java5之后就有了Callable接口。



简单实现带返回值的线程

代码如下：CallableFuture类

package com.test.thread;
 
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
 
public class CallableFuture {
  public static void main(String[] args) {
    
    //创建一个线程池
    ExecutorService pool = Executors.newFixedThreadPool(3) ;
    
    //创建三个有返回值的任务
    CallableTest callableTest1 = new CallableTest("我是线程1") ;
    CallableTest callableTest2 = new CallableTest("我是线程2") ;
    CallableTest callableTest3 = new CallableTest("我是线程3") ;
    
    Future future1 = pool.submit(callableTest1) ;
    Future future2 = pool.submit(callableTest2) ;
    Future future3 = pool.submit(callableTest3) ;
    
    try {
      System.out.println(future1.get().toString());
      System.out.println(future2.get().toString());
      System.out.println(future3.get().toString());
    } catch (InterruptedException e) {
      e.printStackTrace();
    } catch (ExecutionException e) {
      e.printStackTrace();
    }finally{
      pool.shutdown();
    }
    
  }
}

代码如下：CallableTest类

package com.test.thread;
 
import java.util.concurrent.Callable;
 
public class CallableTest implements Callable {
  
  private String threadName ;
  
  public CallableTest(String threadName) {
    this.threadName = threadName;
  }

  @Override
  public Object call() throws Exception {
    return threadName+"返回的信息";
  }
}

运行结果


我是线程1返回的信息
我是线程2返回的信息
我是线程3返回的信息