代理服务器实现联网功能的java代码,可以用浏览器通过代理服务器上网,可通过dns服务器解析域名,可以识别http和url协议
时间: 2023-07-15 18:10:16 浏览: 42
以下是一个简单的代理服务器实现联网功能的Java代码,包括DNS解析和处理HTTP和URL协议请求:
```java
import java.io.*;
import java.net.*;
import java.util.*;
public class ProxyServer {
private static final int BUFFER_SIZE = 32768;
public static void main(String args[]) {
int port = 8080;
try {
ServerSocket server = new ServerSocket(port);
System.out.println("Proxy Server Started on Port " + port + "...");
while (true) {
Socket client = server.accept();
Thread thread = new Thread(new ProxyThread(client));
thread.start();
}
} catch (IOException e) {
System.err.println("Error starting Proxy Server on Port " + port + ": " + e.getMessage());
}
}
}
class ProxyThread implements Runnable {
private Socket client;
private InputStream fromClient;
private OutputStream toClient;
public ProxyThread(Socket client) {
this.client = client;
}
public void run() {
try {
fromClient = client.getInputStream();
toClient = client.getOutputStream();
byte[] request = new byte[BUFFER_SIZE];
int bytesRead = fromClient.read(request, 0, BUFFER_SIZE);
String header = new String(request, 0, bytesRead);
StringTokenizer tokenizer = new StringTokenizer(header);
tokenizer.nextToken(); // skip method
String url = tokenizer.nextToken();
int index = url.indexOf("//");
String protocol = url.substring(0, index - 1);
url = url.substring(index + 2);
index = url.indexOf("/");
String host = url.substring(0, index);
String path = url.substring(index);
String command = tokenizer.nextToken();
if (command.equalsIgnoreCase("GET")) {
handleGetRequest(protocol, host, path);
} else {
handleOtherRequest(header);
}
} catch (IOException e) {
System.err.println("Error handling client request: " + e.getMessage());
} finally {
try {
client.close();
} catch (IOException e) {
System.err.println("Error closing client socket: " + e.getMessage());
}
}
}
private void handleGetRequest(String protocol, String host, String path) throws IOException {
int port = 80;
if (protocol.equalsIgnoreCase("https")) {
port = 443;
}
InetAddress address = InetAddress.getByName(host);
Socket proxy = new Socket(address, port);
OutputStream toServer = proxy.getOutputStream();
toServer.write(("GET " + path + " HTTP/1.0\r\n\r\n").getBytes());
byte[] response = new byte[BUFFER_SIZE];
InputStream fromServer = proxy.getInputStream();
int bytesRead = fromServer.read(response, 0, BUFFER_SIZE);
while (bytesRead != -1) {
toClient.write(response, 0, bytesRead);
bytesRead = fromServer.read(response, 0, BUFFER_SIZE);
}
proxy.close();
}
private void handleOtherRequest(String header) throws IOException {
toClient.write("HTTP/1.0 501 Not Implemented\r\n".getBytes());
toClient.write("Content-Type: text/html\r\n\r\n".getBytes());
toClient.write("<html><head><title>Not Implemented</title></head><body>501 Not Implemented</body></html>".getBytes());
}
}
```
说明:
1. 该代理服务器监听8080端口,并在接收到客户端连接请求时启动一个新线程处理请求。
2. 在处理客户端请求时,首先解析HTTP请求中的URL,获取协议、主机和路径信息。
3. 如果是GET请求,就使用Socket连接到目标主机,并将请求发送到目标服务器上,并将响应返回给客户端。
4. 如果是其他类型的请求,则返回501 Not Implemented错误。