Java内容重新整理删除过期的东西

Java/JavaDemo/codedemo/java/util/future/HelloFuture.java

@@ -0,0 +1,106 @@
+package cn.aofeng.demo.java.util.future;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.log4j.Logger;
+
+/**
+ * Future、Callable练习。
+ * 
+ * @author <a href="mailto:aofengblog@163.com">聂勇</a>
+ */
+public class HelloFuture {
+
+    private static Logger _logger = Logger.getLogger(HelloFuture.class);
+
+    /**
+     * @param args
+     * @throws InterruptedException 
+     */
+    public static void main(String[] args) throws InterruptedException {
+        executeSingleTask();
+        executeBatchTask();
+    }
+
+    /**
+     * 执行单个异步任务：<br>
+     * 1、用submit方法向线程池提交一个任务。<br>
+     * 2、获取结果时，指定了超时时间。<br><br>
+     * 结果：超时后，调用者收到TimeoutException，但实际上任务还在继续执行。
+     * @throws InterruptedException
+     */
+    private static void executeSingleTask() throws InterruptedException {
+        ExecutorService threadpool = Executors.newFixedThreadPool(6);
+        try {
+            Future<Integer> f = threadpool.submit(createCallable(5 * 1000));
+            Object result = f.get(3, TimeUnit.SECONDS);
+            System.out.println("单个任务的执行结果："+result);
+        } catch (Exception e) {
+            _logger.error("线程执行任务时出错", e);
+        } finally {
+            threadpool.shutdown();
+            threadpool.awaitTermination(10, TimeUnit.SECONDS);
+        }
+    }
+
+    /**
+     * 执行多个异步任务：<br>
+     * 1、用invokeAll方法向线程池提交多个任务，并指定了执行的超时时间。<br><br>
+     * 结果：超时后，未执行完成的任务被取消，在调用Future的get方法时，取消的任务会抛出CancellationException，执行完成的任务可获得结果。
+     * @throws InterruptedException
+     */
+    private static void executeBatchTask() throws InterruptedException {
+        ExecutorService threadpool = Executors.newFixedThreadPool(6);
+        List<Callable<Integer>> tasks = new ArrayList<Callable<Integer>>();
+        tasks.add(createCallable(2000));
+        tasks.add(createCallable(5000));
+        tasks.add(createCallable(2500));
+        
+        long startTime = System.currentTimeMillis();
+        try {
+            List<Future<Integer>> fs = threadpool.invokeAll(tasks, 3, TimeUnit.SECONDS);
+            int result = 0;
+            for (Future<Integer> f : fs) {
+                try{
+                    result += f.get();
+                } catch(CancellationException ce) {
+                    // nothing
+                }
+            }
+            System.out.println("执行三个任务共耗时：" + (System.currentTimeMillis() - startTime) + "毫秒");
+            System.out.println("三个任务的执行结果汇总："+result);
+        } catch (Exception e) {
+            _logger.error("线程执行任务时出错", e);
+        } finally {
+            threadpool.shutdown();
+            threadpool.awaitTermination(10, TimeUnit.SECONDS);
+        }
+    }
+    
+    /**
+     * 创建需要长时间执行的任务模拟对象。
+     * @param sleepTimes 线程休眠时间（单位：毫秒）
+     * @return {@link Callable}对象
+     */
+    private static Callable<Integer> createCallable(final int sleepTimes) {
+        Callable<Integer> c = new Callable<Integer>() {
+
+            @Override
+            public Integer call() throws Exception {
+                Thread.sleep(sleepTimes);
+                System.out.println(Thread.currentThread().getName() + ": I'm working");
+                return 9;
+            }
+        };
+        
+        return c;
+    }
+
+}