本篇内容介绍了“Android应用程序启动是怎么实现的”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
成都创新互联公司是一家专业从事网站建设、网络营销、小程序定制开发、网站运营为一体的建站企业；在网站建设告别千篇一律，告别似曾相识，这一次我们重新定义网站建设，让您的网站别具一格。自适应网站建设，实现全网营销！一站适应多终端，一样的建站，不一样的体验！
Android应用程序进程在启动的时候， 会在进程中加载ActivityThread类，并且执行这个类的main函数。
应用程序的消息循环过程就是在这个main函数里面实现的。
我们来看看这个函数的实现，它定义在frameworks/base/core/java/android/app/ActivityThread.java文件中：
[java] view plaincopypublic final class ActivityThread { ...... public static final void main(String[] args) { ...... Looper.prepareMainLooper(); ...... ActivityThread thread = new ActivityThread(); thread.attach(false); ...... Looper.loop(); ...... thread.detach(); ...... } }这个函数做了两件事情，一是在主线程中创建了一个ActivityThread实例，二是通过Looper类使主线程进入消息循环中，这里我们只关注后者。
首先看Looper.prepareMainLooper函数的实现，这是一个静态成员函数，定义在frameworks/base/core/java/android/os/Looper.java文件中：
[java] view plaincopypublic class Looper { ...... private static final ThreadLocal sThreadLocal = new ThreadLocal(); final MessageQueue mQueue; ...... /** Initialize the current thread as a looper. * This gives you a chance to create handlers that then reference * this looper, before actually starting the loop. Be sure to call * {@link #loop()} after calling this method, and end it by calling * {@link #quit()}. */ public static final void prepare() { if (sThreadLocal.get() != null) { throw new RuntimeException("Only one Looper may be created per thread"); } sThreadLocal.set(new Looper()); } /** 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. * {@link #prepare()} */ public static final void prepareMainLooper() { prepare(); setMainLooper(myLooper()); if (Process.supportsProcesses()) { myLooper().mQueue.mQuitAllowed = false; } } private synchronized static void setMainLooper(Looper looper) { mMainLooper = looper; } /** * Return the Looper object associated with the current thread. Returns * null if the calling thread is not associated with a Looper. */ public static final Looper myLooper() { return (Looper)sThreadLocal.get(); } private Looper() { mQueue = new MessageQueue(); mRun = true; mThread = Thread.currentThread(); } ...... }“Android应用程序启动是怎么实现的”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识可以关注创新互联网站，小编将为大家输出更多高质量的实用文章！
