解释ExecutorService接口。

ExecutorService接口是Executor接口的子接口，并添加了管理生命周期的功能。 请考虑以下示例代码：

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class TestThread {
public static void main(final String[] arguments) throws InterruptedException {
ExecutorService e = Executors.newSingleThreadExecutor();

  try {  
     e.submit(new Thread());  
     System.out.println("Shutdown executor");  
     e.shutdown();  
     e.awaitTermination(5, TimeUnit.SECONDS);  
  } catch (InterruptedException ex) {  
     System.err.println("tasks interrupted");  
  } finally {  

     if (!e.isTerminated()) {  
        System.err.println("cancel non-finished tasks");  
     }  
     e.shutdownNow();  
     System.out.println("shutdown finished");  
  }  

}

static class Task implements Runnable {

  public void run() {  

     try {  
        Long duration = (long) (Math.random() * 20);  
        System.out.println("Running Task!");  
        TimeUnit.SECONDS.sleep(duration);  
     } catch (InterruptedException ex) {  
        ex.printStackTrace();  
     }  
  }  

}
} Java

执行上面示例代码，得到以下结果：

Shutdown executor shutdown finished

      
import java.util.concurrent.ExecutorService;  
import java.util.concurrent.Executors;  
import java.util.concurrent.TimeUnit;  
  
public class TestThread {  
   public static void main(final String[] arguments) throws InterruptedException {  
      ExecutorService e = Executors.newSingleThreadExecutor();  
  
      try {  
         e.submit(new Thread());  
         System.out.println("Shutdown executor");  
         e.shutdown();  
         e.awaitTermination(5, TimeUnit.SECONDS);  
      } catch (InterruptedException ex) {  
         System.err.println("tasks interrupted");  
      } finally {  
  
         if (!e.isTerminated()) {  
            System.err.println("cancel non-finished tasks");  
         }  
         e.shutdownNow();  
         System.out.println("shutdown finished");  
      }  
   }  
  
   static class Task implements Runnable {  
        
      public void run() {  
           
         try {  
            Long duration = (long) (Math.random() * 20);  
            System.out.println("Running Task!");  
            TimeUnit.SECONDS.sleep(duration);  
         } catch (InterruptedException ex) {  
            ex.printStackTrace();  
         }  
      }  
   }         
}