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(diào)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(diào)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<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;
}
}
當前名稱: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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