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其实，我已经在android模拟器（ps：它们都运行成功，并与android genric交叉编译器编译）server.c和client.c做测试。 ，然后我走得更远，我通过jni.But重写了客户端，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。 搜索后，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，问题仍然出现。 而随着logcat的显示，java代码实际上调用了c方法，但是，它为什么不像client.c一样呢？ 任何想法都会让我受益匪浅。提前感谢！通过ndk连接套接字编程的错误
的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： 包gz.kaiwii;
public class NSocket {
static{
System.loadLibrary("NSocket");
}
public native void start();
}
本地代码：
/* 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);
}
的logcat的： 
我已经编辑它与logcat.thx！ –
服务器正在监听吗？如何在连接失败时打印错误消息？为此，使用errno和strerror。 –
@MārtiņšMožeiko，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，则everyhing运行正常。 –