Android中检测当前是否为主线程最可靠的解决方法

/**
 * 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;
    }
}