ActivityThread-->Android的主線程。

main方法.png

H.png

HcodeToString.png

HhandleMessage.png

main方法通過Looper獲取主線程既棺、結(jié)束主線程璃吧。
H就是ActivityThread的Handler饮怯，主要包含了四大組件的啟動(dòng)和停止等過程。
通過ApplicationThread和AMS進(jìn)行進(jìn)程間通信榛泛，AMS以進(jìn)程間通信的方式完成ActivityThread的請(qǐng)求后會(huì)回到ApplicationThread中的Binder方法蝌蹂，然后ApplicationThread會(huì)向H發(fā)送消息，H收到消息后會(huì)將ApplicationThread中的邏輯切換到ActivityThread中執(zhí)行曹锨，即切換到主線程中去執(zhí)行孤个，這個(gè)過程就是主線程的消息循環(huán)模式。

Looper

子線程中用Handler的方法.png

prepare.png

loop.png

quit.png

MessageQueue

next

    Message next() {
        // Return here if the message loop has already quit and been disposed.
        // This can happen if the application tries to restart a looper after quit
        // which is not supported.
        final long ptr = mPtr;
        if (ptr == 0) {
            return null;
        }

        int pendingIdleHandlerCount = -1; // -1 only during first iteration
        int nextPollTimeoutMillis = 0;
        for (;;) {
            if (nextPollTimeoutMillis != 0) {
                Binder.flushPendingCommands();
            }

            nativePollOnce(ptr, nextPollTimeoutMillis);

            synchronized (this) {
                // Try to retrieve the next message.  Return if found.
                final long now = SystemClock.uptimeMillis();
                Message prevMsg = null;
                Message msg = mMessages;
                if (msg != null && msg.target == null) {
                    // Stalled by a barrier.  Find the next asynchronous message in the queue.
                    do {
                        prevMsg = msg;
                        msg = msg.next;
                    } while (msg != null && !msg.isAsynchronous());
                }
                if (msg != null) {
                    if (now < msg.when) {
                        // Next message is not ready.  Set a timeout to wake up when it is ready.
                        nextPollTimeoutMillis = (int) Math.min(msg.when - now, Integer.MAX_VALUE);
                    } else {
                        // Got a message.
                        mBlocked = false;
                        if (prevMsg != null) {
                            prevMsg.next = msg.next;
                        } else {
                            mMessages = msg.next;
                        }
                        msg.next = null;
                        if (DEBUG) Log.v(TAG, "Returning message: " + msg);
                        msg.markInUse();
                        return msg;
                    }
                } else {
                    // No more messages.
                    nextPollTimeoutMillis = -1;
                }

                // Process the quit message now that all pending messages have been handled.
                if (mQuitting) {
                    dispose();
                    return null;
                }

                // If first time idle, then get the number of idlers to run.
                // Idle handles only run if the queue is empty or if the first message
                // in the queue (possibly a barrier) is due to be handled in the future.
                if (pendingIdleHandlerCount < 0
                        && (mMessages == null || now < mMessages.when)) {
                    pendingIdleHandlerCount = mIdleHandlers.size();
                }
                if (pendingIdleHandlerCount <= 0) {
                    // No idle handlers to run.  Loop and wait some more.
                    mBlocked = true;
                    continue;
                }

                if (mPendingIdleHandlers == null) {
                    mPendingIdleHandlers = new IdleHandler[Math.max(pendingIdleHandlerCount, 4)];
                }
                mPendingIdleHandlers = mIdleHandlers.toArray(mPendingIdleHandlers);
            }

            // Run the idle handlers.
            // We only ever reach this code block during the first iteration.
            for (int i = 0; i < pendingIdleHandlerCount; i++) {
                final IdleHandler idler = mPendingIdleHandlers[i];
                mPendingIdleHandlers[i] = null; // release the reference to the handler

                boolean keep = false;
                try {
                    keep = idler.queueIdle();
                } catch (Throwable t) {
                    Log.wtf(TAG, "IdleHandler threw exception", t);
                }

                if (!keep) {
                    synchronized (this) {
                        mIdleHandlers.remove(idler);
                    }
                }
            }

            // Reset the idle handler count to 0 so we do not run them again.
            pendingIdleHandlerCount = 0;

            // While calling an idle handler, a new message could have been delivered
            // so go back and look again for a pending message without waiting.
            nextPollTimeoutMillis = 0;
        }
    }

enqueueMessage.png

quit.png

removeAllFutureMessagesLocked.png

Message

callback.png

obtain.png

recycle.png

recycleUnchecked.png

Handler

Handler構(gòu)造方法.png

Callback.png

dispatchMessage.png

post.png

循環(huán).png

handleMessage.png

send.png

sendMessageAtTime.png

enqueueMessage.png

ThreadLocal

hash.png

set.png

initializeValues.png

values.png

values.put.png

Hander機(jī)制

總.png