java并发之线程执行器（Executor）

 1 public class Task implements Runnable {
 2     private String name;
 3     
 4     public Task(String name){
 5         this.name=name;
 6     }
 7     @Override
 8     public void run() {
 9         }
10 }

 1 public class FactorialCalculator implements Callable<Integer> {
 2     private Integer number;
 3     public FactorialCalculator(Integer number){
 4         this.number=number;
 5     }
 6     
 7     @Override
 8     public Integer call() throws Exception {
 9         int num, result;
10         
11         num=number.intValue();
12         result=1;
13         
14         // If the number is 0 or 1, return the 1 value
15         if ((num==0)||(num==1)) {
16             result=1;
17         } else {
18             // Else, calculate the factorial
19             for (int i=2; i<=number; i++) {
20                 result*=i;
21                 Thread.sleep(20);
22             }
23         }
24         System.out.printf("%s: %d\n",Thread.currentThread().getName(),result);
25         // Return the value
26         return result;
27     }
28 }

1 ScheduledExecutorService executor=Executors.newScheduledThreadPool(1);
2 
3         Task task=new Task("Task");
4         ScheduledFuture<?> result=executor.scheduleAtFixedRate(task, 1, 2, TimeUnit.SECONDS);

 1     UserValidator ldapValidator=new UserValidator("LDAP");
 2         UserValidator dbValidator=new UserValidator("DataBase");
 3         
 4         // Create two tasks for the user validation objects
 5         TaskValidator ldapTask=new TaskValidator(ldapValidator, username, password);
 6         TaskValidator dbTask=new TaskValidator(dbValidator,username,password);
 7         
 8         // Add the two tasks to a list of tasks
 9         List<TaskValidator> taskList=new ArrayList<>();
10         taskList.add(ldapTask);
11         taskList.add(dbTask);
12         
13         // Create a new Executor
14         ExecutorService executor=(ExecutorService)Executors.newCachedThreadPool();
15         String result;
16         try {
17             // Send the list of tasks to the executor and waits for the result of the first task 
18             // that finish without throw and Exception. If all the tasks throw and Exception, the
19             // method throws and ExecutionException.
20             result = executor.invokeAny(taskList);
21             System.out.printf("Main: Result: %s\n",result);
22         } catch (InterruptedException e) {
23             e.printStackTrace();
24         } catch (ExecutionException e) {
25             e.printStackTrace();
26         }
27         
28         // Shutdown the Executor
29         executor.shutdown();

 1 Task task=new Task();
 2         
 3         Future<String> result=executor.submit(task);
 4         
 5         try {
 6             TimeUnit.SECONDS.sleep(2);
 7         } catch (InterruptedException e) {
 8             e.printStackTrace();
 9         }
10         
11         System.out.printf("Main: Cancelling the Task\n");
12         result.cancel(true);

1 public V get() throws InterruptedException, ExecutionException {
2         int s = state;
3         if (s <= COMPLETING)
4             s = awaitDone(false, 0L);
5         return report(s);
6     }

 1 public class ResultTask extends FutureTask<String> {
 2 @Override
 3     protected void done() {
 4         if (isCancelled()) {
 5             System.out.printf("%s: Has been cancelled\n",name);
 6         } else {
 7             System.out.printf("%s: Has finished\n",name);
 8         }
 9     }
10 }

 1 public static void main(String[] args) {
 2         // Create the controller for the Rejected tasks
 3         RejectedTaskController controller=new RejectedTaskController();
 4         // Create the executor and establish the controller for the Rejected tasks
 5         ThreadPoolExecutor executor=(ThreadPoolExecutor)Executors.newCachedThreadPool();
 6         executor.setRejectedExecutionHandler(controller);
 7         
 8         // Lauch three tasks
 9         System.out.printf("Main: Starting.\n");
10         for (int i=0; i<3; i++) {
11             Task task=new Task("Task"+i);
12             executor.submit(task);
13         }
14         
15         // Shutdown the executor
16         System.out.printf("Main: Shuting down the Executor.\n");
17         executor.shutdown();
18         // Send another task
19         System.out.printf("Main: Sending another Task.\n");
20         Task task=new Task("RejectedTask");
21         executor.submit(task);
22         
23         // The program ends
24         System.out.printf("Main: End.\n");
25         
26     }

Main: Starting.
Main: Shuting down the Executor.
Main: Sending another Task.
RejectedTaskController: The task java.util.concurrent.FutureTask@60e53b93 has been rejected
RejectedTaskController: java.util.concurrent.ThreadPoolExecutor@5e2de80c[Shutting down, pool size = 3, active threads = 3, queued tasks = 0, completed tasks = 0]
RejectedTaskController: Terminating: true
RejectedTaksController: Terminated: false
Main: End.
Task Task1: Starting
Task Task0: Starting
Task Task2: Starting
Task Task1: ReportGenerator: Generating a report during 4 seconds
Task Task0: ReportGenerator: Generating a report during 7 seconds
Task Task2: ReportGenerator: Generating a report during 6 seconds
Task Task1: Ending
Task Task2: Ending
Task Task0: Ending