| 提交 | 用户 | 时间 | ||
| c5bdf3 | 1 | package com.mandi.fendan.util; |
| A | 2 | |
| 3 | import javax.validation.constraints.NotNull; | |
| 4 | import java.util.concurrent.LinkedBlockingQueue; | |
| 5 | import java.util.concurrent.ThreadFactory; | |
| 6 | import java.util.concurrent.ThreadPoolExecutor; | |
| 7 | import java.util.concurrent.TimeUnit; | |
| 8 | import java.util.concurrent.atomic.AtomicInteger; | |
| 9 | ||
| 10 | /** | |
| 11 | * 线程池的工具类 | |
| 12 | * 用于进行线程的管理，防止重复创建、杀死线程。 | |
| 13 | * | |
| 14 | ||
| 15 | * 多线程运行期间，如果系统不断的创建、杀死新线程， | |
| 16 | * 会产生过度消耗系统资源，以及过度切换线程的问题，甚至可能导致系统资源的崩溃。 | |
| 17 | * 因此需要线程池，对线程进行管理。 | |
| 18 | */ | |
| 19 | public class ThreadPoolUtil { | |
| 20 | ||
| 21 | private String TAG = getClass().getName(); | |
| 22 | private static volatile ThreadPoolUtil mInstance; | |
| 23 | //核心线程池的数量，同时能够执行的线程数量 | |
| 24 | private int corePoolSize; | |
| 25 | //最大线程池数量，表示当缓冲队列满的时候能继续容纳的等待任务的数量 | |
| 26 | private int maxPoolSize; | |
| 27 | //存活时间 | |
| 28 | private long keepAliveTime = 1; | |
| 29 | private TimeUnit unit = TimeUnit.HOURS; | |
| 30 | private ThreadPoolExecutor executor; | |
| 31 | ||
| 32 | private ThreadPoolUtil() { | |
| 33 | //给corePoolSize赋值：当前设备可用处理器核心数*2 + 1,能够让cpu的效率得到最大程度执行（有研究论证的） | |
| 34 | corePoolSize = Runtime.getRuntime().availableProcessors() * 2 + 1; | |
| 35 | maxPoolSize = corePoolSize; | |
| 36 | executor = new ThreadPoolExecutor( | |
| 37 | //当某个核心任务执行完毕，会依次从缓冲队列中取出等待任务 | |
| 38 | corePoolSize, | |
| 39 | // 然后new LinkedBlockingQueue(),然后maximumPoolSize,但是它的数量是包含了corePoolSize的 | |
| 40 | maxPoolSize, | |
| 41 | //表示的是maximumPoolSize当中等待任务的存活时间 | |
| 42 | keepAliveTime, | |
| 43 | unit, | |
| 44 | //缓冲队列，用于存放等待任务，Linked的先进先出 | |
| 45 | new LinkedBlockingQueue(), | |
| 46 | new DefaultThreadFactory(Thread.NORM_PRIORITY, "thread-pool-"), | |
| 47 | new ThreadPoolExecutor.AbortPolicy() | |
| 48 | ); | |
| 49 | } | |
| 50 | ||
| 51 | public static ThreadPoolUtil getInstance() { | |
| 52 | if (mInstance == null) { | |
| 53 | synchronized (ThreadPoolUtil.class) { | |
| 54 | if (mInstance == null) { | |
| 55 | mInstance = new ThreadPoolUtil(); | |
| 56 | } | |
| 57 | } | |
| 58 | } | |
| 59 | return mInstance; | |
| 60 | } | |
| 61 | ||
| 62 | /** | |
| 63 | * 执行任务 | |
| 64 | * | |
| 65 | * @param runnable | |
| 66 | */ | |
| 67 | public void execute(Runnable runnable) { | |
| 68 | if (executor == null) { | |
| 69 | executor = new ThreadPoolExecutor( | |
| 70 | corePoolSize, | |
| 71 | maxPoolSize, | |
| 72 | keepAliveTime, | |
| 73 | TimeUnit.SECONDS, | |
| 74 | new LinkedBlockingQueue(), | |
| 75 | new DefaultThreadFactory(Thread.NORM_PRIORITY, "thread-pool-"), | |
| 76 | new ThreadPoolExecutor.AbortPolicy()); | |
| 77 | } | |
| 78 | if (runnable != null) { | |
| 79 | executor.execute(runnable); | |
| 80 | } | |
| 81 | } | |
| 82 | ||
| 83 | /** | |
| 84 | * 移除任务 | |
| 85 | * | |
| 86 | * @param runnable | |
| 87 | */ | |
| 88 | public void remove(Runnable runnable) { | |
| 89 | if (runnable != null) { | |
| 90 | executor.remove(runnable); | |
| 91 | } | |
| 92 | } | |
| 93 | ||
| 94 | private static class DefaultThreadFactory implements ThreadFactory { | |
| 95 | //线程池的计数 | |
| 96 | private static final AtomicInteger poolNumber = new AtomicInteger(1); | |
| 97 | //线程的计数 | |
| 98 | private final AtomicInteger threadNumber = new AtomicInteger(1); | |
| 99 | private final ThreadGroup group; | |
| 100 | private final String namePrefix; | |
| 101 | private final int threadPriority; | |
| 102 | ||
| 103 | DefaultThreadFactory(int threadPriority, String threadNamePrefix) { | |
| 104 | this.threadPriority = threadPriority; | |
| 105 | this.group = Thread.currentThread().getThreadGroup(); | |
| 106 | this.namePrefix = threadNamePrefix + poolNumber.getAndIncrement() + "-thread-"; | |
| 107 | } | |
| 108 | ||
| 109 | @Override | |
| 110 | public Thread newThread(@NotNull Runnable r) { | |
| 111 | Thread thread = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0); | |
| 112 | // 返回True该线程就是守护线程 | |
| 113 | // 守护线程应该永远不去访问固有资源，如：数据库、文件等。因为它会在任何时候甚至在一个操作的中间发生中断。 | |
| 114 | if (thread.isDaemon()) { | |
| 115 | thread.setDaemon(false); | |
| 116 | } | |
| 117 | thread.setPriority(threadPriority); | |
| 118 | return thread; | |
| 119 | } | |
| 120 | } | |
| 121 | } | |
