NDK学习笔记(十一) POSIX Sockect 本地通信

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1.本地通信，原生服务端、java客户端

这个例子中，原生代码实现了本地服务端，java代码实现了本地客户端。本地服务端使用了之前tcp通信的某些方法。

（1）函数介绍（C/C++）

创建原生本地socket

/*** 创建原生本地socket* @param env* @param obj* @return*/
static int NewLocalSocket(JNIEnv *env, jobject obj) {LogMessage(env, obj, "创建本地socket");int localSocket = socket(PF_LOCAL, SOCK_STREAM, 0);if (-1 == localSocket) {ThrowErrnoException(env, "java/io/IOException", errno);}return localSocket;
}

将本地socket与Name绑定

本地socket命名空间：
Abstract namespace：在本地socket通信协议模块中维护，socket名以NULL字符为前缀绑定socket名。
Filesystem namespace：通过文件系统以一个特殊socket文件的形式维护，socket名直接传递给sockaddr_un结构，将socket名与socket绑定。

/*** 将本地socket与某一名称绑定**/
static void BindLocalSocketToName(JNIEnv *env, jobject obj, int sd, const char *name) {struct sockaddr_un address;//长度const size_t nameLength = strlen(name);size_t pathLength = nameLength;//如果名字不以“/”开头，则在Abstract namespacebool abstractNamespace = ('/' != name[0]);//抽象命名空间要求目录的第一个字节是0字节，更新路径长度包括0字节if (abstractNamespace) {pathLength++;}if (pathLength > sizeof(address.sun_path)) {ThrowException(env, "java/io/IOException", "名字太长");} else {memset(&address, 0, sizeof(address));address.sun_family = PF_LOCAL;char *sunPath = address.sun_path;//第一字节必须是0以使用抽象命名空间if (abstractNamespace) {*sunPath++ = NULL;}strcpy(sunPath, name);//地址长度，offsetof会生成一个类型为 size_t 的整型常量，它是一个结构成员相对于结构开头的字节偏移量。socklen_t addressLength = (offsetof(struct sockaddr_un, sun_path)) + pathLength;//如果socket名已经绑定，取消连接unlink(address.sun_path);LogMessage(env, obj, "绑定到本地名称%s%s", (abstractNamespace) ? "(null)" : "", name);if (-1 == bind(sd, (struct sockaddr *) &address, addressLength)) {ThrowErrnoException(env, "java/io/IOException", errno);}}
}

接收本地socket

/*** 阻塞并等待socket上客户端的连接* @param env* @param obj* @param sd* @return*/
static int AcceptOnLocalSocket(JNIEnv *env, jobject obj, int sd) {LogMessage(env, obj, "等待客户端连接");int clientSocket = accept(sd, NULL, NULL);if (-1 == clientSocket) {ThrowErrnoException(env, "java/io/IOException", errno);}return clientSocket;
}

启动Socket Server

/*** 启动本地unix socket 服务器*/
extern "C"
JNIEXPORT void JNICALL
Java_com_example_testnt_LocalEchoActivity_nativeStartLocalServer(JNIEnv *env, jobject thiz,jstring name) {int serverSocket = NewLocalSocket(env, thiz);if (NULL == env->ExceptionOccurred()) {const char *nameText = env->GetStringUTFChars(name, NULL);if (NULL == nameText) {goto exit;}//绑定BindLocalSocketToName(env, thiz, serverSocket, nameText);env->ReleaseStringUTFChars(name, nameText);if (NULL != env->ExceptionOccurred()) {goto exit;}ListenOnSocket(env, thiz, serverSocket, 4);if (NULL != env->ExceptionOccurred()) {goto exit;}int clientSocket = AcceptOnLocalSocket(env, thiz, serverSocket);if (NULL != env->ExceptionOccurred()) {goto exit;}char buffer[MAX_BUFFER_SZIE];ssize_t recvSize;ssize_t sentSize;while (1) {recvSize = ReceiveFromSocket(env, thiz, clientSocket, buffer, MAX_BUFFER_SZIE);if ((0 == recvSize) || (NULL != env->ExceptionOccurred())) {break;}sentSize = SendToSocker(env, thiz, clientSocket, buffer, (size_t) recvSize);if ((0 == sentSize) || (NULL != env->ExceptionOccurred())) {break;}}close(clientSocket);}exit:if (serverSocket > 0) {close(serverSocket);}
}

运行效果

详细代码请看下面的连接，运行时启动LocalEchoActivity界面。

https://gitee.com/xd_box/NDK_Socket

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