请用Java实现一个简单的HTTP服务器，描述其工作原理

原创左手的ㄟ右手 2025-03-17 23:57 39阅读 0赞

Java中实现一个简单HTTP服务器主要基于Socket编程和Http协议理解。以下是一个基本的示例：

```java
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class SimpleHTTPServer {
    private static final int PORT = 8000; // 你可以选择任何未被使用的端口

public static void main(String[] args) throws IOException {
        // 创建服务器Socket，监听PORT
        ServerSocket serverSocket = new ServerSocket(PORT);

System.out.println("HTTP Server is running on port " + PORT);

// 等待客户端连接
        Socket clientSocket = serverSocket.accept();

System.out.println("Client connected: " + clientSocket.getInetAddress().getHostAddress());

handleRequest(clientSocket);
    }

private static void handleRequest(Socket socket) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())));

String requestLine = in.readLine();
        // print the received request line
        System.out.println("Received Request Line: " + requestLine);

// get the HTTP method and resource path
        String[] parts = requestLine.split(" ");
        String httpMethod = parts[0];
        String resourcePath = parts[1];

// handle the request based on HTTP method
        switch (httpMethod) {
            case "GET":
                serveResource(resourcePath, socket);
                break;
            case "POST":
                handlePostRequest(resourcePath, in, socket));
                break;
            default:
                sendHttpResponse(socket, httpStatusCode.NOT_IMPLEMENTED));
                break;
        }
    }

private static void serveResource(String resourcePath, Socket socket) throws IOException {
        File file = new File(resourcePath);
        // If the path is a file
        if (file.isFile()) {
            FileInputStream fis = new FileInputStream(file);
            byte[] content = new byte[(int)file.length()]];
            fis.read(content);
            fis.close();

sendHttpResponse(socket, httpStatusCode.OK);
            sendResponseContent(socket, content);
        } else { // If the path is a directory
            File[] files = file.listFiles();
            if (files != null && files.length > 0) {
                StringBuilder sb = new StringBuilder();
                for (File file : files) {
                    sb.append("<li><a href='" + file.getAbsolutePath() + "'>").append(file.getName()).append("</a></li>");
                }
                sendHttpResponse(socket, httpStatusCode.OK);
                sendResponseContent(socket, sb.toString().getBytes()));
            } else { // If the directory is empty
                sendHttpResponse(socket, httpStatusCode.OK);
                sendResponseContent(socket, "Directory is empty!".getBytes()));
            }
        }
    }

private static void handlePostRequest(String resourcePath, BufferedReader in, Socket socket) throws IOException {
        System.out.println("Handling POST request for resource: " + resourcePath);

// Read the posted content
        StringBuilder sb = new StringBuilder();
        String line;
        while ((line = in.readLine()) != null)) {
            sb.append(line);
        }

System.out.println("Received POST content: " + sb.toString());

// Process the posted content based on resource path
        if (resourcePath.equals("/submit-data"))) {
            processPostData(sb.toString(), socket));
        } else { // If the resource path is not handled, send 404 status code
            System.out.println("Resource path: " + resourcePath + " is not handled. Sending 404 status code.");
            sendHttpResponse(socket, httpStatusCode.NOT_FOUND));
        }
    }

private static void processPostData(String data, Socket socket) throws IOException {
        // Process the posted data based on your requirements
        // For example, you can store the data in a database or perform some calculations with the data

System.out.println("Received POST data: " + data));

// Send a confirmation response to the client
        sendHttpResponse(socket, httpStatusCode.OK));
    }

private static void sendHttpResponse(Socket socket, int statusCode) throws IOException {
        OutputStream outputStream = socket.getOutputStream();
        System.out.println("Sending HTTP response with status code: " + statusCode);

// Write the HTTP response header and status code to the output stream
        outputStream.write("HTTP/1.1 " + statusCode + "\r\n");

// Write the body content of the HTTP response (if any)
        outputStream.write("Content-Type: text/plain\r\n");
        outputStream.write("Body Content: This is a sample HTTP response body.\r\n\r\n");

// Close the output stream to free resources
        outputStream.close();
    }
}
```

这段Java代码实现了一个简单的HTTP服务器，它监听8000端口，并处理客户端的GET请求。当接收到POST请求时，会将内容读取并进行一些处理（在这个例子中，只是打印出来）。最后，会发送一个确认响应给客户端。

注意：在实际生产环境中，你需要考虑更多因素，如错误处理、多线程处理并发请求等。