Android中检测当前是否为主线程

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public static boolean isInMainThread() { return Looper.myLooper() == Looper.getMainLooper(); }

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private boolean isInMainThread() { Looper myLooper = Looper.myLooper(); Looper mainLooper = Looper.getMainLooper(); Log.i(LOGTAG, "isInMainThread myLooper=" + myLooper + ";mainLooper=" + mainLooper); return myLooper == mainLooper; }

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Log.i(LOGTAG, "testInMainThread inMainThread=" + isInMainThread());

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I/TestInMainThread(32028): isInMainThread myLooper=Looper{40d35ef8};mainLooper=Looper{40d35ef8} I/TestInMainThread(32028): testInMainThread inMainThread=true

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new Thread() { @Override public void run() { Log.i(LOGTAG, "testIn NOT in MainThread isMainThread=" + isInMainThread()); super.run(); } }.start();

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I/TestInMainThread(32028): isInMainThread myLooper=null;mainLooper=Looper{40d35ef8} I/TestInMainThread(32028): testIn NOT in MainThread isMainThread=false

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new Thread() { private Handler mHandler; @Override public void run() { Looper.prepare(); mHandler = new Handler() { public void handleMessage(Message msg) { // process incoming messages here } }; Log.i(LOGTAG, "testInNonMainLooperThread isMainThread=" + isInMainThread()); Looper.loop(); } }.start();

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I/TestInMainThread(32028): isInMainThread myLooper=Looper{40d72c58};mainLooper=Looper{40d35ef8} I/TestInMainThread(32028): testInNonMainLooperThread isMainThread=false

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// sThreadLocal.get() will return null unless you've called prepare(). static final ThreadLocal<Looper> sThreadLocal = new ThreadLocal<Looper>(); private static Looper sMainLooper; // guarded by Looper.class /** * Initialize the current thread as a looper, marking it as an * application's main looper. The main looper for your application * is created by the Android environment, so you should never need * to call this function yourself. See also: {@link #prepare()} */ public static void prepareMainLooper() { prepare(false); synchronized (Looper.class) { if (sMainLooper != null) { throw new IllegalStateException("The main Looper has already been prepared."); } sMainLooper = myLooper(); } } private static void prepare(boolean quitAllowed) { if (sThreadLocal.get() != null) { throw new RuntimeException("Only one Looper may be created per thread"); } sThreadLocal.set(new Looper(quitAllowed)); } /** * Return the Looper object associated with the current thread. * Returns null if the calling thread is not associated with a Looper. */ public static Looper myLooper() { return sThreadLocal.get(); } /** Returns the application's main looper, which lives in the main thread of the application. */ public static Looper getMainLooper() { synchronized (Looper.class) { return sMainLooper; } }