Java 建立執行緒池的四種方式
#1、newCachedThreadPool 建立一個可快取執行緒池，如果執行緒池長度超過處理需要，可靈活回收空閒線程，若無可回收，則新線程。
2、newFixedThreadPool 建立一個定長執行緒池，可控制執行緒最大並發數，超出的執行緒會在佇列中等待。
3、newScheduledThreadPool 建立一個定長執行緒池，支援定時及週期性任務執行。
4、newSingleThreadExecutor 建立一個單執行緒化的執行緒池，它只會用唯一的工作執行緒來執行任務，保證所有任務都按照指定順序(FIFO, LIFO, 優先權)執行。
newCachedThreadPool
建立一個可快取執行緒池，如果執行緒池長度超過處理需要，可靈活回收空閒線程，
若無可回收，則新建執行緒。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | package cn.qbz.thread;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class Test111907 {
public static void main(String[] args) {
ExecutorService executorService = Executors.newCachedThreadPool();
for (int i = 0; i < 10; i++) {
final int temp = i;
executorService.execute(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + " i=" + temp);
}
});
}
}
}
public static ExecutorService newCachedThreadPool() {
return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
60L, TimeUnit.SECONDS,
new SynchronousQueue<Runnable>());
}
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newFixedThreadPool
建立一個定長執行緒池，可控制執行緒最大並發數，超出的執行緒會在佇列中等待。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | package cn.qbz.thread;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class Test111907 {
public static void main(String[] args) {
ExecutorService executorService = Executors.newFixedThreadPool(3);
for (int i = 0; i < 10; i++) {
final int temp = i;
executorService.execute(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + " i=" + temp);
}
});
}
}
}
public static ExecutorService newFixedThreadPool(int nThreads) {
return new ThreadPoolExecutor(nThreads, nThreads,
0L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>());
}
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newScheduledThreadPool
建立一個定長執行緒池，支援定時及週期性任務執行。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | package cn.qbz.thread;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class Test111907 {
public static void main(String[] args) {
final long begin = System.currentTimeMillis();
ExecutorService executorService = Executors.newScheduledThreadPool(3);
for (int i = 0; i < 10; i++) {
final int temp = i;
final long time = begin;
executorService.schedule(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + " i=" + temp + " time=" + (System.currentTimeMillis() - time));
}
}, 5, TimeUnit.SECONDS);
}
}
}
public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
return new ScheduledThreadPoolExecutor(corePoolSize);
}
public ScheduledThreadPoolExecutor(int corePoolSize) {
super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS,
new DelayedWorkQueue());
}
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newSingleThreadExecutor
建立一個單執行緒化的執行緒池，它只會用唯一的工作執行緒來執行任務，
#保證所有任務依照指定順序(FIFO, LIFO, 優先權)執行。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | package cn.qbz.thread;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class Test111907 {
public static void main(String[] args) {
ExecutorService executorService = Executors.newSingleThreadExecutor();
for (int i = 0; i < 10; i++) {
final int temp = i;
executorService.execute(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + " i=" + temp);
}
});
}
}
}
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