标签：led 复用 sni 功能 news 核心 单位 ble ret
1）提升性能。创建和消耗对象费时费CPU资源
2）防止内存过度消耗。控制活动线程的数量，防止并发线程过多。
我们来看一下线程池的简单的构造
public ThreadPoolExecutor(int corePoolSize,
int maximumPoolSize,
long keepAliveTime,
TimeUnit unit,
BlockingQueue workQueue,
ThreadFactory threadFactory,
RejectedExecutionHandler handler) {...}使用上面的方式创建线程池的话，我们需要配置一堆东西，非常麻烦，所以我们不建议这么使用。而是推荐使用Executors的工厂方法来创建线程池，Executors类是官方提供的一个工厂类，它里面封装好了众多功能不一样的线程池。下面就介绍几个常用的线程池。public ThreadPoolExecutor( //核心线程数，除非allowCoreThreadTimeOut被设置为true，否则它闲着也不会死 int corePoolSize, //最大线程数，活动线程数量超过它，后续任务就会排队 int maximumPoolSize, //超时时长，作用于非核心线程（allowCoreThreadTimeOut被设置为true时也会同时作用于核心线程），闲置超时便被回收 long keepAliveTime, //枚举类型，设置keepAliveTime的单位，有TimeUnit.MILLISECONDS（ms）、TimeUnit. SECONDS（s）等 TimeUnit unit, //缓冲任务队列，线程池的execute方法会将Runnable对象存储起来 BlockingQueue<Runnable> workQueue, //线程工厂接口，只有一个new Thread(Runnable r)方法，可为线程池创建新线程 ThreadFactory threadFactory)
public static ExecutorService newFixThreadPool(int nThreads){
return new ThreadPoolExecutor(nThreads, nThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>());
}
//使用
Executors.newFixThreadPool(5).execute(r); 
public static ExecutorService newCachedThreadPool(int nThreads){
return new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60L, TimeUnit. SECONDS, new SynchronousQueue<Runnable>());
}
//使用
Executors.newCachedThreadPool().execute(r); 
public static ExecutorService newSingleThreadPool (int nThreads){
return new FinalizableDelegatedExecutorService ( new ThreadPoolExecutor (1, 1, 0, TimeUnit. MILLISECONDS, new LinkedBlockingQueue<Runnable>()) );
}
//使用
Executors.newSingleThreadPool ().execute(r); 
public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize){
return new ScheduledThreadPoolExecutor(corePoolSize);
}
public ScheduledThreadPoolExecutor(int corePoolSize){
super(corePoolSize, Integer.MAX_VALUE, 0, NANOSECONDS, new DelayedQueue ());
}
//使用，延迟1秒执行，每隔2秒执行一次Runnable r
Executors. newScheduledThreadPool (5).scheduleAtFixedRate(r, 1000, 2000, TimeUnit.MILLISECONDS); 
ExecutorService priorityThreadPool = new ThreadPoolExecutor(3,3,0L,TimeUnit.SECONDS,new PriorityBlockingQueue());
public abstract class PriorityRunnable implements Runnable, Comparable {
private int priority;
public PriorityRunnable(int priority) {
if (priority 0)
throw new IllegalArgumentException();
this.priority = priority;
}
@Override
public int compareTo(PriorityRunnable another) {
int my = this.getPriority();
int other = another.getPriority();
return my 1 : my > other ? -1 : 0;
}
@Override
public void run() {
doSth();
}
public abstract void doSth();
public int getPriority() {
return priority;
}
}ExecutorService priorityThreadPool = new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new PriorityBlockingQueue());
for (int i = 1; i 10; i++) {
final int priority = i;
priorityThreadPool.execute(new PriorityRunnable(priority) {
@Override
public void doSth() {
String threadName = Thread.currentThread().getName();
Log.v("zxy", "线程：" + threadName + ",正在执行优先级为：" + priority + "的任务");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
标签：led 复用 sni 功能 news 核心 单位 ble ret
原文地址：http://blog.csdn.net/xiangzhihong8/article/details/52856327
