Activity的Window和WindowManager的创建过程(二)

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在这篇文章中, 我们分析一下ContextImpl的getSystemService函数,
1     public Object getSystemService(String name) {
2         ServiceFetcher fetcher = SYSTEM_SERVICE_MAP.get(name);
3         return fetcher == null ? null : fetcher.getService(this);
4     }
第2行(ContextImpl->getSystemService)SYSTEM_SERVICE_MAP的定义如下:
private static final HashMap SYSTEM_SERVICE_MAP = new HashMap();
    在ContextImpl加载过程中, 会初始化SYSTEM_SERVICE_MAP, 我们这里只关心LAYOUT_INFLATER_SERVICE服务, 相关代码如下:
        static {
            ............
            registerService(LAYOUT_INFLATER_SERVICE, new ServiceFetcher() {
                    public Object createService(ContextImpl ctx) {
                        return PolicyManager.makeNewLayoutInflater(ctx.getOuterContext());
                    }});

            ............
        }
ContextImpl类的registerService函数的定义如下:
1     private static int sNextPerContextServiceCacheIndex = 0;
    2     private static void registerService(String serviceName, ServiceFetcher fetcher) {
    3         if (!(fetcher instanceof StaticServiceFetcher)) {
    4             fetcher.mContextCacheIndex = sNextPerContextServiceCacheIndex++;
    5         }
    6         SYSTEM_SERVICE_MAP.put(serviceName, fetcher);
    7     }
    registerService函数很好理解吧.
    我们回到getSystemService的第3行(ContextImpl->getSystemService), 这里会调用ServiceFetcher的getService函数, ServiceFetcher是ContextImpl的一个内部类, ServiceFetcher的getService函数定义如下:
    1         public Object getService(ContextImpl ctx) {
    2             ArrayList