手写简单WEB应用服务，搞懂Tomcat

思路

• 启动Socket服务，循环接收浏览器请求
• 接收到请求之后，将流中的数据取出
• 判断目标资源是否存在，若不存在，返回404
• 若存在，将目标资源通过输出流响应给客户端

类

• Server 开启Socket服务
• Request 封装请求，处理请求的相关业务
• Response 封装响应，处理相应的相关业务
• Test 测试类

---

Test类

public class Test {
    public static void main(String[] args) {
        System.out.println("Server startup successfully");
        MyHttpServer myHttpServer = new MyHttpServer();
        myHttpServer.receiving();
    }
}

MyHttpServer类

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class MyHttpServer {
    private int port = 8080;

    public void receiving() {
        try {
            ServerSocket serverSocket = new ServerSocket(port);
            // 循环接受请求
            while (true) {
                // 获取连接对象
                Socket socket = serverSocket.accept();
                // 获取连接对象的输入流
                InputStream inputStream = socket.getInputStream();
                System.out.println(inputStream);
                // 创建Request对象
                MyHttpRequest request = new MyHttpRequest(inputStream);
                // 解析请求
                request.parse();
                // 创建Response
                OutputStream outputStream = socket.getOutputStream();
                MyHttpResponse response = new MyHttpResponse(outputStream);
                // 进行响应
                response.sendResponse(request.getUri());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

MyHttpRequest类

import java.io.IOException;
import java.io.InputStream;

public class MyHttpRequest {
    private InputStream inputStream;
    private String uri;

    public MyHttpRequest(InputStream inputStream) {
        this.inputStream = inputStream;
    }

    public void parse() {
        try {
            byte[] bytes = new byte[1024];
            inputStream.read(bytes);
            String request = new String(bytes);
            parseUri(request);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void parseUri(String request) {
        int index1, index2;
        index1 = request.indexOf(' ');
        index2 = request.indexOf(' ', index1 + 1);
        uri = request.substring(index1 + 1, index2);
        System.out.println(uri);
    }

    public String getUri() {
        return this.uri;
    }
}

MyHttpResponse类

import java.io.*;

public class MyHttpResponse {
    private OutputStream outputStream;

    public MyHttpResponse(OutputStream outputStream) {
        this.outputStream = outputStream;
    }

    public void sendResponse(String uri) {
        // 判断uri是否存在
        String path = System.getProperty("user.dir") + "/001java/WebContent" + uri;
        File file = new File(path);
        if (file.exists()) {
            // 返回目标资源数据
            try {
                byte[] bytes = new byte[(int)file.length()];
                FileInputStream fileInputStream = new FileInputStream(file);
                fileInputStream.read(bytes);
                String result = new String(bytes);
                String response = getResponseMessage("200", result);
                this.outputStream.write(response.getBytes());
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }else {
            // 返回404
            String error = getResponseMessage("404", " File Not Found!");
            System.out.println(error);
            try {
                this.outputStream.write(error.getBytes());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public String getResponseMessage(String code, String message) {
        return "HTTP/1.1" + code + "\r\n"
                + "Content-Type: text/html\r\n"
                + "Content-Length: " + message.length()
                + "\r\n"
                + "\r\n"
                + message;
    }
}

文件目录

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访问存在文件

访问不存在文件