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目的：实现本地 C程序与apk的socket通信。
原理：没有涉及到网络通信，所以使用Android封装的local socket要更简单
参考：系统源码RIL模块
整理：Andy.xie
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C程序 服务端：
1) server_fd = socket_local_server (SOCKET_NAME_XXH,
C 客户端：ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);2) s_fdListen = listen(server_fd, 4);3) while((socket = accept(server_fd, NULL, NULL)) > 0)
1) fd = socket_local_client( SOCKET_NAME_XXH ,
ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
2) write(fd, "hello", 5);
JAVA 客户端：
1) localSocket = new LocalSocket();
2) localSocket.connect(new LocalSocketAddress(socketAddress));
3) OutputStream os = localSocket.getOutputStream();
Namespace:
LocalSocketAddress.Namespace ABSTRACT A socket in the Linux abstract namespace
LocalSocketAddress.Namespace FILESYSTEM A socket named with a normal filesystem path.
LocalSocketAddress.Namespace RESERVED A socket in the Android reserved namespace in /dev/socket.