HandlerThread源码分析

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HandlerThread源码分析

public class HandlerThread extends Thread {    //线程优先级    int mPriority;    //线程id    int mTid = -1;    Looper mLooper;    public HandlerThread(String name) {        super(name);        mPriority = Process.THREAD_PRIORITY_DEFAULT;    }    public HandlerThread(String name, int priority) {        super(name);        mPriority = priority;    }    //可以覆写，在循环之前做一些处理    protected void onLooperPrepared() {    }    //创建了looper并通知getLooper。在执行getLooper之前必须先执行thread的start方法，不然getLooper将返回null，容易引发空指针    @Override    public void run() {        mTid = Process.myTid();        Looper.prepare();        synchronized (this) {            mLooper = Looper.myLooper();            notifyAll();        }        Process.setThreadPriority(mPriority);        onLooperPrepared();        Looper.loop();        mTid = -1;    }    public Looper getLooper() {        if (!isAlive()) {            return null;        }        synchronized (this) {            while (isAlive() && mLooper == null) {                try {                    wait();                } catch (InterruptedException e) {                }            }        }        return mLooper;    }    //looper停止接收新的任务并清空MessageQueue中的任务    public boolean quit() {        Looper looper = getLooper();        if (looper != null) {            looper.quit();            return true;        }        return false;    }    //looper停止接收新的任务并清空MessageQueue中的延时任务，非延时任务将继续执行    public boolean quitSafely() {        Looper looper = getLooper();        if (looper != null) {            looper.quitSafely();            return true;        }        return false;    }    public int getThreadId() {        return mTid;    }}

Looper#quit相关源码

public void quit() {        mQueue.quit(false);    }public void quitSafely() {    mQueue.quit(true);}void quit(boolean safe) {        if (!mQuitAllowed) {            throw new IllegalStateException("Main thread not allowed to quit.");        }        synchronized (this) {            if (mQuitting) {                return;            }            mQuitting = true;            if (safe) {                removeAllFutureMessagesLocked();            } else {                removeAllMessagesLocked();            }            // We can assume mPtr != 0 because mQuitting was previously false.            nativeWake(mPtr);        }    }private void removeAllMessagesLocked() {        Message p = mMessages;        while (p != null) {            Message n = p.next;            p.recycleUnchecked();            p = n;        }        mMessages = null;    }    private void removeAllFutureMessagesLocked() {        final long now = SystemClock.uptimeMillis();        Message p = mMessages;        if (p != null) {            if (p.when > now) {                removeAllMessagesLocked();            } else {                Message n;                for (;;) {                    n = p.next;                    if (n == null) {                        return;                    }                    if (n.when > now) {                        break;                    }                    p = n;                }                p.next = null;                do {                    p = n;                    n = p.next;                    p.recycleUnchecked();                } while (n != null);            }        }    }

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