手写一个民用Tomcat （06）

手写一个简易的民用Tomcat需要实现基本的Web服务器功能，例如接收HTTP请求、解析请求、处理静态资源和Servlet处理。以下是一个非常简化的实现，仅提供基本功能以理解原理：

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;
 
public class SimpleTomcat {
    private int port = 8080;
    private String webAppDirectory = "webapp";
    private Map<String, Servlet> servlets = new HashMap<>();
 
    public SimpleTomcat(String webAppDirectory) {
        this.webAppDirectory = webAppDirectory;
    }
 
    public void start() throws IOException {
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("Server started on port " + port);
 
        while (true) {
            Socket clientSocket = serverSocket.accept();
            processRequest(clientSocket);
        }
    }
 
    private void processRequest(Socket clientSocket) throws IOException {
        InputStream inputStream = clientSocket.getInputStream();
        OutputStream outputStream = clientSocket.getOutputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        PrintWriter writer = new PrintWriter(outputStream, true);
 
        // 简化：只处理GET方法，不处理POST和其他HTTP方法
        String requestLine = reader.readLine();
        String method = requestLine.split(" ")[0];
        if (!method.equalsIgnoreCase("GET")) {
            writer.println("HTTP/1.1 405 Method Not Allowed");
            writer.println("Content-Type: text/plain");
            writer.println();
            writer.println("Method Not Allowed");
            return;
        }
 
        String path = requestLine.split(" ")[1];
        if (path.equals("/")) {
            path += "index.html"; // 默认页面
        }
 
        File file = new File(webAppDirectory, path);
        if (file.exists()) {
            writer.println("HTTP/1.1 200 OK");
            writer.println("Content-Type: text/html");
            writer.println();
            writeFileContent(writer, file);
        } else {
            Servlet servlet = servlets.get(path);
            if (servlet != null) {
                servlet.service(writer, reader);
            } else {
                writer.println("HTTP/1.1 404 Not Found");
                writer.println("Content-Type: text/plain");
                writer.println();
                writer.println("Not Found");
            }
        }
 
        writer.close();
        reader.