我嘗試通過 JNI 在 Linux 機器上打開套接字連接。如果我將 Java_Socket_socket 和 Java_Socket_bind 組合在同一個 C 函式中，JNI 呼叫可以完美運行，但是當我按順序運行方法時它不起作用。
這是我的代碼
#include <jni.h> // JNI header provided by JDK
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <fcntl.h>
#include "Socket.h" // Generated
JNIEXPORT jint JNICALL Java_Socket_socket(JNIEnv *env, jobject thisObj) {
int sockfd;
if ((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
printf("socket creation failed...\n");
return (jint)-1;
} else {
printf("Socket successfully created..\n");
printf("Socket descriptor: %d\n", sockfd);
return (jint) sockfd;
}
}
JNIEXPORT jint JNICALL Java_Socket_bind(JNIEnv *env, jobject thisObj, jint sockfd, jint port) {
struct sockaddr_in servaddr;
bzero(&servaddr, sizeof(servaddr));
int c_sockfd = (int) sockfd;
short int c_port = (int) port;
printf("socket binding sockfd - %d, port - %d\n", c_sockfd, c_port);
// assign IP, PORT
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(c_port);
printf("htons - %d\n", htons(c_port));
int one = 1;
int res = setsockopt(c_sockfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
res = setsockopt(c_sockfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (res < 0) {
perror("setsockopt");
}
printf("sizeof - %d\n", sizeof(servaddr));
if (fcntl(c_sockfd, F_GETFD) != -1 || errno != EBADF) {
printf("fd is valid\n");
} else {
printf("fd is invalid\n");
}
// Binding newly created socket to given IP and verification
if ((bind(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr))) != 0) {
printf("socket bind failed...\n");
printf("Error code: %d\n", errno);
return (jint)-1;
}
else {
printf("Socket successfully binded..\n");
return (jint)0;
}
}
Java 代碼
public class Socket {
static {
System.load(".../libsocket.so");
}
private native int socket();
private native int bind(int sockFd, int port);
public static void main(String[] args) {
var socket = new Socket();
int sockFd = socket.socket();
System.out.println("sockFd " sockFd);
int bind = socket.bind(sockFd, 9900);
System.out.println("Bind " bind);
}
}
輸出：
Socket descriptor: 4
socket binding sockfd - 4, port - 9900
htons - 44070
sizeof - 16
fd is valid
socket bind failed...
Error code: 22
如果我從此代碼創建 C 程式，并且作為常規 C 程式，gcc ... && a.out-> 則不會發生錯誤。可能是什么原因？
可能是因為檔案描述符已關閉嗎？
uj5u.com熱心網友回復：
問題是您將AF_UNIX套接字視為AF_INET一個。您不能sockaddr_in用于AF_UNIX套接字，也不能將其系結到 IP 地址。
我認為您在套接字定義代碼中打錯了字。代替
if ((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
它應該是
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
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