自分でHTTPプロトコルを実現する

序文
最近HTTPプロトコルを研究していますので、自分で実現したいと思います.HTTPプロトコルはTCP/IPプロトコル族のアプリケーション層で働いています.トランスポート層で使うTCPの構造は大体このようです.

新聞はこのようです.

実現する
ここではSocketを使って実現し、ドメイン名解析の機能を追加しました.

package com.example;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class MyHttpClient {

    public static class HTTPAddress {
        String hostAddress;
        int point = 80;

        public HTTPAddress(String hostAddress, int point) {
            this.hostAddress = hostAddress;
            this.point = point;
        }

    }

    public static void main(String[] args) {
        String url = "http://blog.csdn.net/qq_22706515/article/details/51819472";
        getStringByUrl(url);


    }

    public static final String HTTP_HEAD = "http://";

    public static HTTPAddress getHTTPAddress(String url) {
        if (url == null || url.equals("")) {
            return null;
        }
        String head = "";
        //    80
        int point = 80;
        if (url.startsWith(HTTP_HEAD)) {
            url = url.substring(HTTP_HEAD.length());
        }
        //      
        head = url.split("/")[0];
        //   url     ，     
        int index = head.indexOf(":");
        if (index != -1) {
            String pointStr = head.substring(index + 1).trim();
            head = head.substring(0, index);
            point = Integer.valueOf(pointStr);
        }
        try {
            //      ip  
            String hostAddress = InetAddress.getByName(head).getHostAddress();
            HTTPAddress httpAddress = new HTTPAddress(hostAddress, point);
            return httpAddress;
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
        return null;
    }


    public static void getStringByUrl(String url) {
        try {
            HTTPAddress httpAddress = getHTTPAddress(url);
            if (httpAddress == null) {
                return;
            }
            Socket socket = new Socket(httpAddress.hostAddress, httpAddress.point);
            OutputStreamWriter osw = new OutputStreamWriter(socket.getOutputStream());
            StringBuffer sb = new StringBuffer();
            //     ，       \r
  
            sb.append("GET " + url + " HTTP/1.1\r
");
            sb.append("Host: " + httpAddress.hostAddress + ":" + httpAddress.point + "\r
");
            sb.append("Connection: keep-alive\r
");
            //   \r
                  
            sb.append("\r
");
            osw.write(sb.toString());
            osw.flush();
            InputStream is = socket.getInputStream();
            int count = 0;
            byte[] b = new byte[8192];
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            while ((count = is.read(b)) != -1) {
                baos.write(b, 0, count);
            }
            is.close();
            baos.close();
            String result = baos.toString();
            //    ，       ，     
            String separateStr="\r
\r
";
            int index = result.indexOf(separateStr);
            String headStr = result.substring(0, index);
            String contentStr=result.substring(index+separateStr.length());
            System.out.print("head:"+headStr+"
");
            System.out.print("content:"+contentStr+"
");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


}

テスト
これは戻ってきた内容です.自分の必要に応じて部分を取得することができます.