import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.List;import java.util.Random;import java.util.concurrent.Callable;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;public class TestThreadPool { // -newFixedThreadPool與cacheThreadPool差不多，也是能reuse就用，但不能隨時建新的線程 // -其獨特之處:任意時間點，最多只能有固定數目的活動線程存在，此時如果有新的線程要建立，只能放在另外的隊列中等待，直到當前的線程中某個線程終止直接被移出池子 // -和cacheThreadPool不同，FixedThreadPool沒有IDLE機制（可能也有，但既然文檔沒提，肯定非常長，類似依賴上層的TCP或UDP // IDLE機制之類的），所以FixedThreadPool多數針對一些很穩定很固定的正規并發線程，多用于服務器 // -從方法的源代碼看，cache池和fixed 池調用的是同一個底層池，只不過參數不同: // fixed池線程數固定，并且是0秒IDLE（無IDLE） // cache池線程數支持0-Integer.MAX_VALUE(顯然完全沒考慮主機的資源承受能力），60秒IDLE private static ExecutorService fixedService = Executors.newFixedThreadPool(6); // -緩存型池子，先查看池中有沒有以前建立的線程，如果有，就reuse.如果沒有，就建一個新的線程加入池中 // -緩存型池子通常用于執行一些生存期很短的異步型任務 // 因此在一些面向連接的daemon型SERVER中用得不多。 // -能reuse的線程，必須是timeout IDLE內的池中線程，缺省timeout是60s,超過這個IDLE時長，線程實例將被終止及移出池。 // 注意，放入CachedThreadPool的線程不必擔心其結束，超過TIMEOUT不活動，其會自動被終止。 private static ExecutorService cacheService = Executors.newCachedThreadPool(); // -單例線程，任意時間池中只能有一個線程 // -用的是和cache池和fixed池相同的底層池，但線程數目是1-1,0秒IDLE（無IDLE） private static ExecutorService singleService = Executors.newSingleThreadExecutor(); // -調度型線程池 // -這個池子里的線程可以按schedule依次delay執行，或周期執行 private static ExecutorService scheduledService = Executors.newScheduledThreadPool(10); public static void main(String[] args) {  DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  List<Integer> customerList = new ArrayList<Integer>();  System.out.println(format.format(new Date()));  testFixedThreadPool(fixedService, customerList);  System.out.println("--------------------------");  testFixedThreadPool(fixedService, customerList);  fixedService.shutdown();  System.out.println(fixedService.isShutdown());  System.out.println("----------------------------------------------------");  testCacheThreadPool(cacheService, customerList);  System.out.println("----------------------------------------------------");  testCacheThreadPool(cacheService, customerList);  cacheService.shutdownNow();  System.out.println("----------------------------------------------------");  testSingleServiceThreadPool(singleService, customerList);  testSingleServiceThreadPool(singleService, customerList);  singleService.shutdown();  System.out.println("----------------------------------------------------");  testScheduledServiceThreadPool(scheduledService, customerList);  testScheduledServiceThreadPool(scheduledService, customerList);  scheduledService.shutdown(); } public static void testScheduledServiceThreadPool(ExecutorService service, List<Integer> customerList) {  List<Callable<Integer>> listCallable = new ArrayList<Callable<Integer>>();  for (int i = 0; i < 10; i++) {   Callable<Integer> callable = new Callable<Integer>() {    @Override    public Integer call() throws Exception {     return new Random().nextInt(10);    }   };   listCallable.add(callable);  }  try {   List<Future<Integer>> listFuture = service.invokeAll(listCallable);   for (Future<Integer> future : listFuture) {    Integer id = future.get();    customerList.add(id);   }  } catch (Exception e) {   e.printStackTrace();  }  System.out.println(customerList.toString()); } public static void testSingleServiceThreadPool(ExecutorService service, List<Integer> customerList) {  List<Callable<List<Integer>>> listCallable = new ArrayList<Callable<List<Integer>>>();  for (int i = 0; i < 10; i++) {   Callable<List<Integer>> callable = new Callable<List<Integer>>() {    @Override    public List<Integer> call() throws Exception {     List<Integer> list = getList(new Random().nextInt(10));     boolean isStop = false;     while (list.size() > 0 && !isStop) {      System.out.println(Thread.currentThread().getId() + " -- sleep:1000");      isStop = true;     }     return list;    }   };   listCallable.add(callable);  }  try {   List<Future<List<Integer>>> listFuture = service.invokeAll(listCallable);   for (Future<List<Integer>> future : listFuture) {    List<Integer> list = future.get();    customerList.addAll(list);   }  } catch (Exception e) {   e.printStackTrace();  }  System.out.println(customerList.toString()); } public static void testCacheThreadPool(ExecutorService service, List<Integer> customerList) {  List<Callable<List<Integer>>> listCallable = new ArrayList<Callable<List<Integer>>>();  for (int i = 0; i < 10; i++) {   Callable<List<Integer>> callable = new Callable<List<Integer>>() {    @Override    public List<Integer> call() throws Exception {     List<Integer> list = getList(new Random().nextInt(10));     boolean isStop = false;     while (list.size() > 0 && !isStop) {      System.out.println(Thread.currentThread().getId() + " -- sleep:1000");      isStop = true;     }     return list;    }   };   listCallable.add(callable);  }  try {   List<Future<List<Integer>>> listFuture = service.invokeAll(listCallable);   for (Future<List<Integer>> future : listFuture) {    List<Integer> list = future.get();    customerList.addAll(list);   }  } catch (Exception e) {   e.printStackTrace();  }  System.out.println(customerList.toString()); } public static void testFixedThreadPool(ExecutorService service, List<Integer> customerList) {  List<Callable<List<Integer>>> listCallable = new ArrayList<Callable<List<Integer>>>();  for (int i = 0; i < 10; i++) {   Callable<List<Integer>> callable = new Callable<List<Integer>>() {    @Override    public List<Integer> call() throws Exception {     List<Integer> list = getList(new Random().nextInt(10));     boolean isStop = false;     while (list.size() > 0 && !isStop) {      System.out.println(Thread.currentThread().getId() + " -- sleep:1000");      isStop = true;     }     return list;    }   };   listCallable.add(callable);  }  try {   List<Future<List<Integer>>> listFuture = service.invokeAll(listCallable);   for (Future<List<Integer>> future : listFuture) {    List<Integer> list = future.get();    customerList.addAll(list);   }  } catch (Exception e) {   e.printStackTrace();  }  System.out.println(customerList.toString()); } public static List<Integer> getList(int x) {  List<Integer> list = new ArrayList<Integer>();  list.add(x);  list.add(x * x);  return list; }}

//例如：corePoolSize=3,maximumPoolSize=6,LinkedBlockingQueue(10)//RejectedExecutionHandler默認處理方式是：ThreadPoolExecutor.AbortPolicy//ThreadPoolExecutor executorService = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, 1L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(10));//1.如果線程池中（也就是調用executorService.execute）運行的線程未達到LinkedBlockingQueue.init(10)的話，當前執行的線程數是:corePoolSize(3) //2.如果超過了LinkedBlockingQueue.init(10)并且超過的數>=init(10)+corePoolSize(3)的話，并且小于init(10)+maximumPoolSize. 當前啟動的線程數是：(當前線程數-init(10))//3.如果調用的線程數超過了init(10)+maximumPoolSize 則根據RejectedExecutionHandler的規則處理。

//默認使用：ThreadPoolExecutor.AbortPolicy，處理程序遭到拒絕將拋出運行時RejectedExecutionException。			RejectedExecutionHandler policy=new ThreadPoolExecutor.AbortPolicy();//			//在 ThreadPoolExecutor.CallerRunsPolicy 中，線程調用運行該任務的execute本身。此策略提供簡單的反饋控制機制，能夠減緩新任務的提交速度。//			policy=new ThreadPoolExecutor.CallerRunsPolicy();//			//在 ThreadPoolExecutor.DiscardPolicy 中，不能執行的任務將被刪除。//			policy=new ThreadPoolExecutor.DiscardPolicy();//			//在 ThreadPoolExecutor.DiscardOldestPolicy 中，如果執行程序尚未關閉，則位于工作隊列頭部的任務將被刪除，然后重試執行程序（如果再次失敗，則重復此過程）。//			policy=new ThreadPoolExecutor.DiscardOldestPolicy();