Java線程池的幾種實現(xiàn)方法和區(qū)別介紹實例詳解-創(chuàng)新互聯(lián)
下面通過實例代碼為大家介紹Java線程池的幾種實現(xiàn)方法和區(qū)別：
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(shù)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，F(xiàn)ixedThreadPool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(shù)針對一些很穩(wěn)定很固定的正規(guī)并發(fā)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(shù)不同:
// fixed池線程數(shù)固定，并且是0秒IDLE（無IDLE）
// cache池線程數(shù)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(zhí)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(nèi)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(shù)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(zhí)行，或周期執(zhí)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 customerList = new ArrayList();
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 customerList) {
List> listCallable = new ArrayList>();
for (int i = 0; i < 10; i++) {
Callable callable = new Callable() {
@Override
public Integer call() throws Exception {
return new Random().nextInt(10);
}
};
listCallable.add(callable);
}
try {
List> listFuture = service.invokeAll(listCallable);
for (Future 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 customerList) {
List>> listCallable = new ArrayList>>();
for (int i = 0; i < 10; i++) {
Callable> callable = new Callable>() {
@Override
public List call() throws Exception {
List 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>> listFuture = service.invokeAll(listCallable);
for (Future> future : listFuture) {
List list = future.get();
customerList.addAll(list);
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println(customerList.toString());
}
public static void testCacheThreadPool(ExecutorService service, List customerList) {
List>> listCallable = new ArrayList>>();
for (int i = 0; i < 10; i++) {
Callable> callable = new Callable>() {
@Override
public List call() throws Exception {
List 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>> listFuture = service.invokeAll(listCallable);
for (Future> future : listFuture) {
List list = future.get();
customerList.addAll(list);
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println(customerList.toString());
}
public static void testFixedThreadPool(ExecutorService service, List customerList) {
List>> listCallable = new ArrayList>>();
for (int i = 0; i < 10; i++) {
Callable> callable = new Callable>() {
@Override
public List call() throws Exception {
List 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>> listFuture = service.invokeAll(listCallable);
for (Future> future : listFuture) {
List list = future.get();
customerList.addAll(list);
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println(customerList.toString());
}
public static List getList(int x) {
List list = new ArrayList();
list.add(x);
list.add(x * x);
return list;
}
} 網(wǎng)站題目：Java線程池的幾種實現(xiàn)方法和區(qū)別介紹實例詳解-創(chuàng)新互聯(lián)
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