Android之getSystemService方法实现详解

一、概述

Android应用层获取系统java层的service, 用到getSystemService这个API。getSystemService方法定义于context类, 但context类是一个抽象类，它的具

体实现在contextImpl类中, getSystemService方法在contextImpl类中的代码如下:

 

   @Override

   public Object getSystemService(String name) {

       ServiceFetcher fetcher = SYSTEM_SERVICE_MAP.get(name);

       return fetcher == null ? null : fetcher.getService(this);

}

 二、ServiceFetcher类

 

   /*package*/ static class ServiceFetcher {

       int mContextCacheIndex = -1;

 

       /**

        * Main entrypoint; only override if you don't need caching.

        */

       public Object getService(ContextImpl ctx) {

           ArrayList