通过ndk连接套接字编程的错误
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【中文标题】通过ndk连接套接字编程的错误【英文标题】:connect error of socket programming via ndk 【发布时间】:2012-06-24 12:02:07 【问题描述】:实际上,我已经在 android 模拟器中使用 server.c 和 client.c 进行了测试(ps:它们都成功运行并使用 android 通用交叉编译器进行编译)。然后我走得更远,我通过jni重写客户端。但是,在这种情况下,客户端无法连接到服务器端,尽管新客户端与client.c非常相似。
经过搜索,有人提到权限很重要。但是,当我添加<uses-permission android:name="android.permission.INTERNET" />
(ps:此标签在应用程序标签之外)时,问题仍然存在。
正如 logcat 所显示的,java 代码实际上调用了 c 方法,但是,为什么它的行为与 client.c 不同呢?
任何想法都会让我受益匪浅。提前致谢!
server.c:
/* Make the necessary includes and set up the variables. */
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>
int main()
int server_sockfd, client_sockfd;
int server_len, client_len;
struct sockaddr_un server_address;
struct sockaddr_un client_address;
/* Remove any old socket and create an unnamed socket for the server. */
unlink("server_socket");
server_sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
/* Name the socket. */
server_address.sun_family = AF_UNIX;
strcpy(server_address.sun_path, "server_socket");
server_len = sizeof(server_address);
bind(server_sockfd, (struct sockaddr *)&server_address, server_len);
/* Create a connection queue and wait for clients. */
listen(server_sockfd, 5);
while(1)
char ch;
printf("server waiting\n");
/* Accept a connection. */
client_len = sizeof(client_address);
client_sockfd = accept(server_sockfd,
(struct sockaddr *)&client_address, &client_len);
/* We can now read/write to client on client_sockfd. */
read(client_sockfd, &ch, 1);
ch++;
write(client_sockfd, &ch, 1);
close(client_sockfd);
client.c:
/* Make the necessary includes and set up the variables. */
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>
int main()
int sockfd;
int len;
struct sockaddr_un address;
int result;
char ch = 'A';
/* Create a socket for the client. */
sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
/* Name the socket, as agreed with the server. */
address.sun_family = AF_UNIX;
strcpy(address.sun_path, "server_socket");
len = sizeof(address);
/* Now connect our socket to the server's socket. */
result = connect(sockfd, (struct sockaddr *)&address, len);
if(result == -1)
perror("oops: client1");
exit(1);
/* We can now read/write via sockfd. */
write(sockfd, &ch, 1);
read(sockfd, &ch, 1);
printf("char from server = %c\n", ch);
close(sockfd);
exit(0);
java代码: 打包gz.kaiwii;
public class NSocket
static
System.loadLibrary("NSocket");
public native void start();
本机代码:
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
#include <android/log.h>
#include <android/bitmap.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>
#define LOG_TAG "NSocket"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
JNIEXPORT void JNICALL Java_gz_kaiwii_NSocket_start
(JNIEnv * env, jobject object)
LOGI("JNICALL Java_gz_kaiwii_NSocket_start is called!");
int sockfd;
int len;
struct sockaddr_un address;
int result;
char ch = 'A';
/* Create a socket for the client. */
LOGI(" Create a socket for the client!");
sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
if(sockfd==-1)
LOGE("create socket error!!!!!");
/* Name the socket, as agreed with the server. */
address.sun_family = AF_UNIX;
strcpy(address.sun_path, "server_socket");
len = sizeof(address);
/* Now connect our socket to the server's socket. */
result = connect(sockfd, (struct sockaddr *)&address, len);
LOGI(" Now connect our socket to the server's socket.");
if(result == -1)
LOGE("connect error!");
exit(1);
/* We can now read/write via sockfd. */
write(sockfd, &ch, 1);
read(sockfd, &ch, 1);
/*
printf("char from server = %c\n", ch);
*/
LOGI("char from server = %c\n", ch);
close(sockfd);
日志猫:
【问题讨论】:
我已经用 logcat.thx 对其进行了编辑! 服务器在监听吗?如何在连接失败时打印错误消息?为此使用 errno 和 strerror。 @Mārtiņš Možeiko,服务器提示错误,没有这样的文件或目录。并且客户端提示连接被拒绝。但是,如果我不使用jni调用本机代码,一切运行正常. 【参考方案1】:如果我使用抽象命名空间作为名称,一切运行正常。但是,需要注意的一点是长度!
【讨论】:
你的问题对我很有帮助。你能告诉我们是否可以在 jni 本身中同时拥有服务器和客户端吗???如果是这样,我们如何同时启动服务器和客户端分别发送和接收数据...以上是关于通过ndk连接套接字编程的错误的主要内容,如果未能解决你的问题,请参考以下文章