通過上面兩篇文章的學習，我們知道了HTTP\SOCK\TCP\IP之間的關係以及區別，接下來我們手寫一個HTTP伺服器

      首先我們定義一個HttpServer類，該類主要用以建立一個ServerSocket，當有請求進入的時候會通過accept()方法生成一個套接字-Socket物件，然後通過Socket物件的輸入輸出流進行讀取請求資料，並返回請求結果。封裝的輸入流物件為Request,封裝的輸出流物件為Response，並且在最後如果輸入的請求裡包含./shutdown，則關閉伺服器。

     程式碼如下：HttpServer類

package cn.tomcat;

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

/**
 * @description:
 * @author: gongqi
 * @create: 2018/11/07 15:09
 */
public class HttpServer {
    //是否關閉伺服器
    private boolean shutdown = false;
    //監聽的埠號
    private Integer port = 9011;
    //資源所在的根路徑
    public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot";
    //停止服務的命令
    private static final String SHUTDOWN_CMD = "./shutdown";

    
    /**
    *啟動主類
    */
    public static void main(String[] args) {
        HttpServer server = new HttpServer();
        server.await();
    }
    
    /**
    *等待請求
    */
    public void await() {

        //
        ServerSocket serverSocket = null;
        try {
            //啟動一個ServerSocket並監聽對應的埠號
            serverSocket = new ServerSocket(port);
        } catch (IOException e) {
            e.printStackTrace();
        }

        //當未收到關閉命令的時候一直迴圈接受請求
        while (!shutdown) {

            Socket socket;
            InputStream inputStream;
            OutputStream outputStream;

            System.out.println(WEB_ROOT);
            //
            try {
                //此方法是一個阻塞方法
                //當有請求進來的時候會生成一個Socket物件
                socket = serverSocket.accept();
                //獲取輸入流
                inputStream = socket.getInputStream();
                //獲取輸出流
                outputStream = socket.getOutputStream();
                
                //封裝輸入流
                Request request = new Request(inputStream);
                request.parse();
                
                //封裝輸出流
                Response response = new Response(outputStream);
                response.setRequest(request);
                response.sendStaticResource();
                //關閉當次Socket連線
                socket.close();

                shutdown = SHUTDOWN_CMD.equals(request.getUri());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }
}
 

Request類

package cn.tomcat;


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

/**
 * @description:
 * @author: gongqi
 * @create: 2018/11/07 16:20
 */
public class Request {

    private InputStream input;
    private String uri;

    public Request(InputStream input) {
        this.input = input;
    }

    public void parse() {
        //
        StringBuffer request = new StringBuffer(2048);
        int i;
        byte[] buffer = new byte[2048];
        try {
            //在輸入流裡讀取2048個byte，方便起見姑且先死2048吧
            i = input.read(buffer);
        } catch (IOException e) {
            e.printStackTrace();
            i = -1;
        }
        //迴圈byte陣列，然後一個字元一個字元的刷入StringBuffer
        for (int j = 0; j < i; j++) {
            request.append((char)buffer[j]);
        }
        //打印出請求的內容
        System.out.println(request.toString());
        uri = parseUri(request.toString());
    }
    

    private String parseUri(String requestString) {
        int index1, index2;
        index1 = requestString.indexOf(' ');
        if (index1 != -1) {
            index2 = requestString.indexOf(' ', index1 + 1);
            if (index2 > index1) {
                return requestString.substring(index1 + 1, index2);

            }
        }
        return null;
    }

    public String getUri() {
        return uri;
    }


}
 

Response類：

package cn.tomcat;

import java.io.*;

/**
 * @description:
 * @author: gongqi
 * @create: 2018/11/07 16:36
 */
public class Response {

    private static final int BUFFER_SIZE = 1024;
    private Request request;
    private OutputStream output;

    public Response(OutputStream output) {
        this.output = output;
    }

    public void setRequest(Request request) {
        this.request = request;
    }


    public void sendStaticResource() throws IOException {
        byte[] bytes = new byte[BUFFER_SIZE];
        File file = new File(HttpServer.WEB_ROOT + request.getUri());
        if (file.exists()) {
            FileInputStream fileInputStream = null;
            try {
                fileInputStream = new FileInputStream(file);
                int ch = fileInputStream.read(bytes, 0, BUFFER_SIZE);
                while (ch != -1) {
                    output.write(bytes, 0, ch);
                    ch=fileInputStream.read(bytes,0,BUFFER_SIZE);
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } finally {
                if (fileInputStream != null) {
                    fileInputStream.close();
                }
            }
        } else {
            String mesg = "HTTP/1.1 404 File not found\r\n"
                    + "Content-Type: text/html\r\n"
                    + "Content-Length: 23\r\n"
                    + "\r\n"
                    + "<h1>File not found</h1>";
            //
            try {
                output.write(mesg.getBytes());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }
}
 

對應的HTML：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta http-equiv="content-type" content="text/html;charset=utf-8">
</head>
<body>
<h1>你好哇，你成功訪問到我了!</h1>
</body>
</html>

這樣一個簡單的HTTP伺服器就寫好啦，拿去跑一下看吧，哈哈哈哈！！