一、Java内置线程池
1、 Java内置线程池 – ExecutorService
1.1 Executors.newCachedThreadPool()
性能优先模式
n个任务就创建n个线程。执行任务时，若以前的线程可用，则使用；若之前的线程正在忙，则会创建新的线程来执行任务。线程的数量不做限制；当线程空闲到一定时间（默认60秒），会自动销毁。
重载方法：指定线程的创建方式：
Executors.newCachedThreadPool(new ThreadFactory() {
int i = 1;
@Override
public Thread newThread(Runnable r) {
return new Thread(r, “自定义的线程名称:” + i++);
}
});
package com.dhu.thread.threadpool.demo02;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
/**
* Executors获取ExecutorService，调用方法，获取任务
* @author zhou
*
*/
public class MyTest01 {
public static void main(String[] args) {
//test1();
test2();
}
static void test2() {
//1.使用工厂类获取线程池对象，使用 new ThreadFactory()来创建线程
ExecutorService es = Executors.newCachedThreadPool(new ThreadFactory() {
int i = 1;
@Override
public Thread newThread(Runnable r) {
return new Thread(r, "自定义的线程名称:" + i++);
}
});
//2.提交执行任务
for (int i = 0; i < 10; i++) {
es.submit(new MyRunnable(i));
}
}
//newCachedThreadPool()
static void test1() {
//1.使用工厂类获取线程池对象
ExecutorService es = Executors.newCachedThreadPool();
//2.提交执行任务
for (int i = 0; i < 10; i++) {
es.submit(new MyRunnable(i));
}
}
}
/**
* 任务类
* @author zhou
*
*/
class MyRunnable implements Runnable {
private int id;
public MyRunnable(int id) {
this.id = id;
}
@Override
public void run() {
String name = Thread.currentThread().getName();
System.out.println(name + "执行了任务：" + id);
}
}
1.2 Executors.newFixedThreadPool(n)
固定线程数，降低服务器压力
1.3 Executors.newSingleThreadExecutor()
单线程的线程池，安全性
2、Java内置线程池 – ScheduledExecutorService
延迟执行任务
2.1 Executors.newScheduledThreadPool(3)
es.schedule();
//2.创建、提交任务，任务延迟2秒执行
//任务再线程池中执行
es.scheduleAtFixedRate(new MyRunnabel(1), 1, 2, TimeUnit.SECONDS);
package com.dhu.thread.threadpool.demo03;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
/**
* 测试ScheduledExecutorService接口 延迟执行任务和重复执行任务的功能
* @author zhou
*
*/
public class ScheduledExecutorServiceTest01 {
public static void main(String[] args) {
//1.获取一个具备延迟执行任务的线程池对象
ScheduledExecutorService es = Executors.newScheduledThreadPool(3, new ThreadFactory() {
int i = 1;
@Override
public Thread newThread(Runnable r) {
return new Thread(r, "自定义线程名称：" + i++);
}
});
//2.创建、提交任务，任务延迟2秒执行
es.scheduleAtFixedRate(new MyRunnabel(1), 1, 2, TimeUnit.SECONDS);
System.out.println("over");
}
}
class MyRunnabel implements Runnable{
private int id;
public MyRunnabel(int id) {
this.id = id;
}
@Override
public void run() {
String name = Thread.currentThread().getName();
System.out.println(name +"执行任务" + id);
}
}
//2.创建、提交任务，任务延迟2秒执行
//任务再线程池中执行
es.scheduleWithFixedDelay(new MyRunnabe2(3), 1, 2, TimeUnit.SECONDS);
