从0到1实现一个web服务器

demo1/src/main/java/top/yexuejc/demo/Request.java

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+package top.yexuejc.demo;
+
+/**
+ * 请求对象类
+ * @author maxiaofeng
+ * @date 2025/6/19 11:37
+ */
+public class Request {
+    private final String method;
+    private final String path;
+    private final String body;
+    private final String params;
+
+    public Request(String method, String path, String body, String params) {
+        this.method = method;
+        this.path = path;
+        this.body = body;
+        this.params = params;
+    }
+
+    public String getMethod() {
+        return method;
+    }
+
+    public String getPath() {
+        return path;
+    }
+
+    public String getBody() {
+        return body;
+    }
+
+    public String getParams() {
+        return params;
+    }
+}

demo1/src/main/java/top/yexuejc/demo/RequestHandler.java

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+package top.yexuejc.demo;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.net.Socket;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.Objects;
+import java.util.logging.Logger;
+
+/**
+ * 请求处理
+ *
+ * @author maxiaofeng
+ * @date 2025/6/19 11:29
+ */
+public class RequestHandler implements Runnable {
+    Logger logger = Logger.getLogger(RequestHandler.class.getName());
+    private final String OS_NAME = System.getProperty("os.name");
+    private final List<String> STATIC_RESOURCES = List.of("css", "js", "img", "fonts", "favicon.ico");
+
+    private final Socket clientSocket;
+    private final String staticRoot;
+    private final String webRoot;
+
+    public RequestHandler(Socket socket, String staticRoot, String webRoot) {
+        this.clientSocket = socket;
+        this.staticRoot = staticRoot;
+        this.webRoot = webRoot;
+    }
+
+    @Override
+    public void run() {
+        try (InputStream input = clientSocket.getInputStream(); OutputStream output = clientSocket.getOutputStream()) {
+
+            // 解析请求
+            Request request = parseRequest(input);
+
+            // 处理请求并生成响应（静态画面）
+            Response response = handleRequest(request);
+
+            // 画面渲染（动态画面）
+            pageLive(request, response);
+
+            // 发送响应
+            sendResponse(output, response);
+
+        } catch (Exception e) {
+            System.err.println("Error handling request: " + e.getMessage());
+            e.printStackTrace();
+        } finally {
+            try {
+                clientSocket.close();
+            } catch (IOException e) {
+                System.err.println("Error closing client socket: " + e.getMessage());
+                e.printStackTrace();
+            }
+        }
+    }
+
+    private void pageLive(Request request, Response response) {
+        if (!request.getPath().endsWith("html")) {
+            return;
+        }
+        byte[] originalBytes = response.getContent();
+        // 模拟模板引擎
+        // 1. 获取原始的字符串
+        String originalString = new String(originalBytes, StandardCharsets.UTF_8);
+
+        // 2. 替换字符串
+        String replacedString = originalString.replace("${body}", request.getParams());
+
+        // 3. 将替换后的 String 转回 byte[]
+        response.setContent(replacedString.getBytes(StandardCharsets.UTF_8));
+    }
+
+    private Request parseRequest(InputStream input) throws IOException, URISyntaxException {
+        BufferedReader reader = new BufferedReader(new InputStreamReader(input));
+        String requestLine = reader.readLine();
+        if (requestLine == null) {
+            throw new IOException("Empty request");
+        }
+        // GET /index.html?a=1 HTTP/1.1
+        // Host: 127.0.0.1:8080
+        // User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36
+        // Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;
+        // v=b3;q=0.7
+
+        // POST /getUser HTTP/1.1
+        // Content-Type: application/json
+        // User-Agent: PostmanRuntime/7.44.0
+        // Accept: */*
+        // Host: 127.0.0.1:8080
+        // Accept-Encoding: gzip, deflate, br
+        // Connection: keep-alive
+        // Content-Length: 10
+
+        logger.info("=====================================================");
+        logger.info(requestLine);
+        String[] parts = requestLine.split(" ");
+        if (parts.length != 3) {
+            throw new IOException("Invalid request line: " + requestLine);
+        }
+
+        String method = parts[0]; // GET
+        String path = parts[1]; // /index.html
+
+        URI url = new URI(path);
+        path = url.getPath();
+        String params = url.getQuery();
+
+
+        // 读取请求头
+        String headerLine;
+        int contentLength = 0; // 输入流中字节长度
+        while ((headerLine = reader.readLine()) != null && !headerLine.isEmpty()) {
+            logger.info(headerLine);
+            if (method.equals("POST") && headerLine.startsWith("Content-Length:")) {
+                contentLength = Integer.parseInt(headerLine.split(":")[1].trim());
+            }
+        }
+
+        // 读取POST请求体
+        StringBuilder requestBody = new StringBuilder();
+        if (method.equals("POST") && contentLength > 0) {
+            char[] buffer = new char[contentLength];
+            reader.read(buffer, 0, contentLength);
+            requestBody.append(buffer);
+            logger.info("Body: " + requestBody);
+        }
+        logger.info("Params: " + params);
+
+        logger.info("=====================================================");
+        return new Request(method, path, requestBody.toString(), params);
+    }
+
+    private Response handleRequest(Request request) {
+        String path = request.getPath();
+
+        // 默认主页
+        if (path.equals("/")) {
+            path = "/index.html";
+        }
+        path = getAbsolutePath(path);
+
+        // 获取classPath中的文件路径
+        String classPath = Objects.requireNonNull(getClass().getClassLoader().getResource("")).getPath();
+        if (OS_NAME.startsWith("Windows")) {
+            classPath = classPath.substring(1);
+        }
+        Path filePath = Paths.get(classPath, path);
+
+        // 安全检查，防止目录遍历攻击
+        if (!filePath.startsWith(Paths.get(classPath, webRoot)) && !filePath.startsWith(Paths.get(classPath, staticRoot))) {
+            return new Response(403, "Forbidden", "text/plain", "Access denied".getBytes());
+        }
+
+        // 检查文件是否存在且是普通文件
+        if (Files.exists(filePath) && Files.isRegularFile(filePath)) {
+            try {
+                byte[] content = Files.readString(filePath, StandardCharsets.UTF_8).getBytes(StandardCharsets.UTF_8);
+                String contentType = determineContentType(filePath);
+                return new Response(200, "OK", contentType, content);
+            } catch (IOException e) {
+                return new Response(500, "Internal Server Error", "text/plain", "Error reading file".getBytes());
+            }
+        } else {
+            return new Response(404, "Not Found", "text/plain", "Page not found".getBytes());
+        }
+    }
+
+    private String getAbsolutePath(String path) {
+        if (path.startsWith("/") && STATIC_RESOURCES.stream().anyMatch(path::endsWith)) {
+            return staticRoot + path;
+        }
+        return webRoot + path;
+    }
+
+    private String determineContentType(Path filePath) {
+        String fileName = filePath.getFileName().toString();
+        if (fileName.endsWith(".html")) {
+            return "text/html";
+        } else if (fileName.endsWith(".css")) {
+            return "text/css";
+        } else if (fileName.endsWith(".js")) {
+            return "application/javascript";
+        } else if (fileName.endsWith(".png")) {
+            return "image/png";
+        } else if (fileName.endsWith(".jpg") || fileName.endsWith(".jpeg")) {
+            return "image/jpeg";
+        } else {
+            return "application/octet-stream";
+        }
+    }
+
+    private void sendResponse(OutputStream output, Response response) throws IOException {
+        String statusLine = STR."""
+HTTP/1.1 \{response.getStatusCode()} \{response.getStatusMessage()}\r
+""";
+        String headers = STR."""
+Content-Type: \{response.getContentType()}\r
+Content-Length: \{response.getContentLength()}\r
+\r
+""";
+
+        output.write(statusLine.getBytes());
+        output.write(headers.getBytes());
+        output.write(response.getContent());
+        output.flush();
+    }
+}

demo1/src/main/java/top/yexuejc/demo/Response.java

@@ -0,0 +1,45 @@
+package top.yexuejc.demo;
+
+/**
+ * 响应对象类
+ * @author maxiaofeng
+ * @date 2025/6/19 11:37
+ */
+public class Response {
+    private final int statusCode;
+    private final String statusMessage;
+    private final String contentType;
+    private  byte[] content;
+
+    public Response(int statusCode, String statusMessage, String contentType, byte[] content) {
+        this.statusCode = statusCode;
+        this.statusMessage = statusMessage;
+        this.contentType = contentType;
+        this.content = content;
+    }
+
+    public int getStatusCode() {
+        return statusCode;
+    }
+
+    public String getStatusMessage() {
+        return statusMessage;
+    }
+
+    public String getContentType() {
+        return contentType;
+    }
+
+    public byte[] getContent() {
+        return content;
+    }
+
+    public int getContentLength() {
+        return content.length;
+    }
+
+    public Response setContent(byte[] content) {
+        this.content = content;
+        return this;
+    }
+}

demo1/src/main/java/top/yexuejc/demo/WebServer.java

@@ -0,0 +1,80 @@
+package top.yexuejc.demo;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.logging.Logger;
+
+/**
+ * web服务核心
+ *
+ * @author maxiaofeng
+ * @date 2025/6/19 11:13
+ */
+public class WebServer {
+    Logger logger = Logger.getLogger(WebServer.class.getName());
+    /** 端口 */
+    private final int port;
+    /** 页面资源文件 */
+    private final String webRoot;
+    /** 静态资源文件 */
+    private final String staticRoot;
+
+    private ServerSocket serverSocket;
+    private boolean isRunning;
+
+    public WebServer() {
+        this(8080, "static", "web");
+    }
+
+    public WebServer(int port, String staticRoot, String webRoot) {
+        this.port = port;
+        this.staticRoot = staticRoot;
+        this.webRoot = webRoot;
+    }
+
+    /**
+     * 启动服务
+     */
+    public void start() {
+        try {
+            serverSocket = new ServerSocket(port);
+            isRunning = true;
+            logger.info("启动Web服务 : http://127.0.0.1:" + port);
+
+            // 阻塞式监听服务是否正常
+            while (isRunning) {
+                try {
+                    Socket clientSocket = serverSocket.accept();
+                    // 新建一个线程处理请求
+                    new RequestHandler(clientSocket, staticRoot, webRoot).run();
+                } catch (IOException e) {
+                    if (isRunning) {
+                        logger.severe("创建连接异常。");
+                        e.printStackTrace();
+                    }
+                }
+            }
+        } catch (Throwable r) {
+            logger.severe("启动Web服务异常。");
+            r.printStackTrace();
+        } finally {
+            stop();
+        }
+    }
+
+    /**
+     * 停止服务
+     */
+    public void stop() {
+        isRunning = false;
+        try {
+            if (serverSocket != null) {
+                serverSocket.close();
+            }
+        } catch (IOException e) {
+            logger.info("停止Web服务异常: " + e.getMessage());
+        }
+        System.out.println("Web服务停止.");
+    }
+}

demo1/src/main/java/top/yexuejc/demo/WebServerApplication.java

@@ -0,0 +1,14 @@
+package top.yexuejc.demo;
+
+/**
+ * web服务器入口
+ *
+ * @author maxiaofeng
+ * @date 2025/6/19 11:11
+ */
+public class WebServerApplication {
+    public static void main(String[] args) {
+        System.setProperty("java.util.logging.SimpleFormatter.format", "%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS [%4$s] %2$s - %5$s%6$s%n");
+        new WebServer().start();
+    }
+}

demo1/src/main/resources/static/css/index.css

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+body {
+    font-family: Arial, sans-serif;
+    max-width: 800px;
+    margin: 0 auto;
+    padding: 20px;
+    color: #333;
+}
+
+h1 {
+    color: #0671dc;
+    /* 让文字左右滚动，并且改变颜色*/
+    text-shadow: 0 0 5px #333;
+    animation: scroll-text 5s linear infinite;
+    animation-fill-mode: forwards;
+    animation-delay: 2s;
+    animation-direction: alternate;
+    animation-iteration-count: infinite;
+    animation-timing-function: ease-in-out;
+    animation-play-state: running;
+    animation-name: scroll-text;
+    animation-duration: 5s;
+}

demo1/src/main/resources/web/index.html

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+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="UTF-8">
+    <title>Simple Web Server</title>
+    <link rel="stylesheet" href="/css/index.css">
+</head>
+<body>
+<h1>Welcome to Simple Web Server</h1>
+<p>This page is served by our custom Java web server!</p>
+<p>你的请求参数是：${body}</p>
+</body>
+</html>