三种阻塞队列
BlockingQueue<Runnable> workQueue = null;
workQueue = new ArrayBlockingQueue<>(5);//基于数组的先进先出队列，有界
workQueue = new LinkedBlockingQueue<>();//基于链表的先进先出队列，无界
workQueue = new SynchronousQueue<>();//无缓冲的等待队列，无界
四种拒绝策略
RejectedExecutionHandler rejected = null;
rejected = new ThreadPoolExecutor.AbortPolicy();//默认，队列满了丢任务抛出异常
rejected = new ThreadPoolExecutor.DiscardPolicy();//队列满了丢任务不异常
rejected = new ThreadPoolExecutor.DiscardOldestPolicy();//将最早进入队列的任务删，之后再尝试加入队列
rejected = new ThreadPoolExecutor.CallerRunsPolicy();//如果添加到线程池失败，那么主线程会自己去执行该任务
如何创建线程池？
直接使用ThreadPoolExecutor类的构造方法就可以创建线程池。我们来看下构造参数：
-
/**
-
-
* corePoolSize 核心线程数
-
-
* maximumPoolSize 最大线程数
-
-
* keepAliveTime idle线程存活时间
-
-
* unit 上个参数的单位
-
-
* workQueue 线程对象的缓冲队列
-
-
* threadFactory 生成线程的工厂(可选
-
-
* handler 达到容量后的回调(可选)
-
-
*/
-
-
public ThreadPoolExecutor(int corePoolSize,
-
-
int maximumPoolSize,
-
-
long keepAliveTime,
-
-
TimeUnit unit,
-
-
BlockingQueue<Runnable> workQueue,
-
-
ThreadFactory threadFactory,
-
-
RejectedExecutionHandler handler)
五种线程池
ExecutorService threadPool = null;
threadPool = Executors.newSingleThreadExecutor();//单线程的线程池，只有一个线程在工作，阻塞队列使用的是LinkedBlockingQueue
threadPool = Executors.newFixedThreadPool(3);//固定大小的线程池，阻塞队列使用的是LinkedBlockingQueue
threadPool = Executors.newCachedThreadPool();//有缓冲的线程池，线程数 JVM 控制，阻塞队列使用的是SynchronousQueue
threadPool = Executors.newScheduledThreadPool(2);//定时任务功能的线程池
threadPool = new ThreadPoolExecutor();//默认线程池，可控制参数比较多
-
public
static
void main (
String[] args) throws
Exception {
-
-
testThreadPoolExecutor();
-
-
}
-
-
public
static
void testThreadPoolExecutor() throws
Exception {
-
-
//基础参数
-
-
int corePoolSize=
2;
//最小活跃线程数
-
-
int maximumPoolSize=
5;
//最大活跃线程数
-
-
int keepAliveTime=
5;
//指定线程池中线程空闲超过 5s 后将被回收
-
-
TimeUnit unit = TimeUnit.SECONDS;
//keepAliveTime 单位
-
-
//阻塞队列
-
-
BlockingQueue<Runnable> workQueue =
null;
-
-
workQueue =
new ArrayBlockingQueue<>(
5);
//基于数组的先进先出队列，有界
-
-
workQueue =
new LinkedBlockingQueue<>();
//基于链表的先进先出队列，无界
-
-
workQueue =
new SynchronousQueue<>();
//无缓冲的等待队列，无界
-
-
//拒绝策略
-
-
RejectedExecutionHandler rejected =
null;
-
-
rejected =
new ThreadPoolExecutor.AbortPolicy();
//默认，队列满了丢任务抛出异常
-
-
rejected =
new ThreadPoolExecutor.DiscardPolicy();
//队列满了丢任务不异常
-
-
rejected =
new ThreadPoolExecutor.DiscardOldestPolicy();
//将最早进入队列的任务删，之后再尝试加入队列
-
-
rejected =
new ThreadPoolExecutor.CallerRunsPolicy();
//如果添加到线程池失败，那么主线程会自己去执行该任务
-
-
//使用的线程池
-
-
ExecutorService threadPool =
null;
-
-
threadPool = Executors.newCachedThreadPool();
//有缓冲的线程池，线程数 JVM 控制
-
-
threadPool = Executors.newFixedThreadPool(
3);
//固定大小的线程池
-
-
threadPool = Executors.newScheduledThreadPool(
2);
-
-
threadPool = Executors.newSingleThreadExecutor();
//单线程的线程池，只有一个线程在工作
-
-
threadPool =
new ThreadPoolExecutor(
-
-
corePoolSize,
-
-
maximumPoolSize,
-
-
keepAliveTime,
-
-
unit,
-
-
workQueue,
-
-
rejected);
//默认线程池，可控制参数比较多
-
-
//执行无返回值线程
-
-
TaskRunnable taskRunnable =
new TaskRunnable();
-
-
threadPool.execute(taskRunnable);
-
-
List<Future<
String>> futres =
new ArrayList<>();
-
-
for(
int i=
0;i<
10;i++) {
-
-
//执行有返回值线程
-
-
TaskCallable taskCallable =
new TaskCallable(i);
-
-
Future<
String> future = threadPool.submit(taskCallable);
-
-
futres.add(future);
-
-
}
-
-
for(
int i=
0;i<futres.size();i++){
-
-
String result = futres.get(i).get();
-
-
System.out.println(i+
" result = "+result);
-
-
}
-
-
}
-
-
/**
-
-
* 返回值的线程，使用 threadpool.execut() 执行
-
-
*/
-
-
public
static
class TaskRunnable implements Runnable{
-
-
@Override
-
-
public
void run() {
-
-
try {
-
-
Thread.sleep(
1000);
-
-
}
catch (InterruptedException e) {
-
-
e.printStackTrace();
-
-
}
-
-
System.out.println(Thread.currentThread().getName() +
" runnable result!");
-
-
}
-
-
}
-
-
/**
-
-
* 有返回值的线程，使用 threadpool.submit() 执行
-
-
*/
-
-
public
static
class TaskCallable implements Callable<String>{
-
-
public TaskCallable(
int index){
-
-
this.i=index;
-
-
}
-
-
private
int i;
-
-
@Override
-
-
public
String call() throws
Exception {
-
-
int r =
new Random().nextInt(
5);
-
-
try {
-
-
Thread.sleep(r);
-
-
}
catch (InterruptedException e) {
-
-
e.printStackTrace();
-
-
}
-
-
//System.out.println("callable result!");
-
-
return Thread.currentThread().getName()+
" callable index="+i +
",sleep="+r;
-
-
}
-
-
}
转载：https://blog.csdn.net/qq_17010193/article/details/114587375