Question

我正在尝试实现TCP服务器-客户端应用程序。服务器是用C ++编写的，客户端是用Java编写的。

TCP服务器正在使用CURL和Mozilla浏览器，但不能与CHROME以及Java客户端一起使用。
客户端脚本可以访问服务器，但不能检索响应并从服务器消息中打印。

Client.java

//client side 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.io.UnsupportedEncodingException;

public class Client {

    public static void main(String[] args) {

        URL url = null;
        try {
            url = new URL("http://192.168.1.101:12345");
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        try {
            for (String line; (line = reader.readLine()) != null;) {
                System.out.println(line);
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

server.cpp


// Server side C/C++ program to demonstrate Socket programming 
#include <unistd.h> 
#include <stdio.h> 
#include <sys/socket.h> 
#include <stdlib.h> 
#include <netinet/in.h> 
#include <string.h> 
#define PORT 12345
int main(int argc, char const *argv[]) 
{ 
    int server_fd, new_socket, valread; 
    struct sockaddr_in address; 
    int opt = 1; 
    int addrlen = sizeof(address); 
    char buffer[1024] = {0}; 
    char *hello = "Hello from server"; 

    // Creating socket file descriptor 
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) 
    { 
        perror("socket failed"); 
        exit(EXIT_FAILURE); 
    } 

    // Forcefully attaching socket to the port 8080 
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, 
                                                &opt, sizeof(opt))) 
    { 
        perror("setsockopt"); 
        exit(EXIT_FAILURE); 
    } 
    address.sin_family = AF_INET; 
    address.sin_addr.s_addr = INADDR_ANY; 
    address.sin_port = htons( PORT ); 

    // Forcefully attaching socket to the port 8080 
    if (bind(server_fd, (struct sockaddr *)&address, 
                                sizeof(address))<0) 
    { 
        perror("bind failed"); 
        exit(EXIT_FAILURE); 
    } 
    if (listen(server_fd, 3) < 0) 
    { 
        perror("listen"); 
        exit(EXIT_FAILURE); 
    } 
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, 
                    (socklen_t*)&addrlen))<0) 
    { 
        perror("accept"); 
        exit(EXIT_FAILURE); 
    } 
    valread = read( new_socket , buffer, 1024); 
    printf("%s\n",buffer ); 
    send(new_socket , hello , strlen(hello) , 0 ); 
    printf("Hello message sent\n"); 
    return 0; 
}

“来自服务器的Hello尚未显示在控制台上，也没有显示java 错误消息：

java.io.IOException: Invalid Http response
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1606)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
    at java.net.URL.openStream(URL.java:1045)
    at com.sri.tcptest.Client.main(Client.java:24)
Exception in thread "main" java.lang.NullPointerException
    at com.srinar.tcptest.Client.main(Client.java:34) "

Answer 1

您的服务器使用无效的HTTP响应进行响应。

要么使其有效，要么使您的客户端不期望它（使用普通套接字而不是HTTP客户端）。

Answer 2

在server.cpp文件中，更改：

char *hello = "HTTP/1.1 200 OK\r\nContent-Length: 17\r\nContent-Type: text/html\r\n\r\nHello from server";

为C ++服务器实现Java TCP客户端

2 个答案: