服务连接
Service Connection
来自 Android 文档：
Android system creates the connection between the client and service,
it calls onServiceConnected() on the ServiceConnection. The
onServiceConnected() method includes an IBinder argument, which the
client then uses to communicate with the bound service.
Android系统调用onServiceConnected()是否使用客户端线程消息队列？
深入了解源代码，用于 post 连接可运行回调的处理程序是 运行 在主线程上。
还有 class 顶部的 java doc 说
Like many callbacks from the system, the methods on this class are called from the main thread of your process.
来自 Android 文档：
Android system creates the connection between the client and service, it calls onServiceConnected() on the ServiceConnection. The onServiceConnected() method includes an IBinder argument, which the client then uses to communicate with the bound service.
Android系统调用onServiceConnected()是否使用客户端线程消息队列？
深入了解源代码，用于 post 连接可运行回调的处理程序是 运行 在主线程上。
还有 class 顶部的 java doc 说
Like many callbacks from the system, the methods on this class are called from the main thread of your process.