package cn.how2j.diytomcat.util;

import java.io.*;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.URL;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import cn.hutool.core.convert.Convert;
import cn.hutool.core.util.ZipUtil;
import cn.hutool.http.HttpUtil;

public class MiniBrowser {

    public static void main(String[] args) throws Exception {
        String url = "http://static.how2j.cn/diytomcat.html";
        String contentString= getContentString(url,false);
        System.out.println(contentString);
        String httpString= getHttpString(url,false);
        System.out.println(httpString);
    }

    public static byte[] getContentBytes(String url) {
        return getContentBytes(url, false);
    }

    public static String getContentString(String url) {
        return getContentString(url,false);
    }

    public static String getContentString(String url, boolean gzip) {
        byte[] result = getContentBytes(url, gzip);
        if(null==result)
            return null;
        try {
            return new String(result,"utf-8").trim();
        } catch (UnsupportedEncodingException e) {
            return null;
        }
    }

    public static byte[] getContentBytes(String url, boolean gzip) {
        byte[] response = getHttpBytes(url,gzip);
        byte[] doubleReturn = "\r\n\r\n".getBytes();

        int pos = -1;
        for (int i = 0; i < response.length-doubleReturn.length; i++) {
            byte[] temp = Arrays.copyOfRange(response, i, i + doubleReturn.length);

            if(Arrays.equals(temp, doubleReturn)) {
                pos = i;
                break;
            }
        }
        if(-1==pos)
            return null;

        pos += doubleReturn.length;

        byte[] result = Arrays.copyOfRange(response, pos, response.length);
        return result;
    }

    public static String getHttpString(String url,boolean gzip) {
        byte[]  bytes=getHttpBytes(url,gzip);
        return new String(bytes).trim();
    }

    public static String getHttpString(String url) {
        return getHttpString(url,false);
    }

    public static byte[] getHttpBytes(String url,boolean gzip) {
        byte[] result = null;
        try {
            URL u = new URL(url);
            Socket client = new Socket();
            int port = u.getPort();
            if(-1==port)
                port = 80;
            InetSocketAddress inetSocketAddress = new InetSocketAddress(u.getHost(), port);
            client.connect(inetSocketAddress, 1000);
            Map<String,String> requestHeaders = new HashMap<>();

            requestHeaders.put("Host", u.getHost()+":"+port);
            requestHeaders.put("Accept", "text/html");
            requestHeaders.put("Connection", "close");
            requestHeaders.put("User-Agent", "how2j mini brower / java1.8");

            if(gzip)
                requestHeaders.put("Accept-Encoding", "gzip");

            String path = u.getPath();
            if(path.length()==0)
                path = "/";

            String firstLine = "GET " + path + " HTTP/1.1\r\n";

            StringBuffer httpRequestString = new StringBuffer();
            httpRequestString.append(firstLine);
            Set<String> headers = requestHeaders.keySet();
            for (String header : headers) {
                String headerLine = header + ":" + requestHeaders.get(header)+"\r\n";
                httpRequestString.append(headerLine);
            }

            PrintWriter pWriter = new PrintWriter(client.getOutputStream(), true);
            pWriter.println(httpRequestString);
            InputStream is = client.getInputStream();

            result = readBytes(is);
            client.close();
        } catch (Exception e) {
            e.printStackTrace();
            try {
                result = e.toString().getBytes("utf-8");
            } catch (UnsupportedEncodingException e1) {
                e1.printStackTrace();
            }
        }

        return result;

    }

    public static byte[] readBytes(InputStream is) throws IOException {
        int buffer_size = 1024;
        byte buffer[] = new byte[buffer_size];
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        while(true) {
            int length = is.read(buffer);
            if(-1==length)
                break;
            baos.write(buffer, 0, length);
            if(length!=buffer_size)
                break;
        }
        byte[] result =baos.toByteArray();
        return result;
    }
}

package cn.how2j.diytomcat.http;

import cn.how2j.diytomcat.util.MiniBrowser;
import cn.hutool.core.util.StrUtil;

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

public class Request {

    private String requestString;
    private String uri;
    private Socket socket;
    public Request(Socket socket) throws IOException {
        this.socket = socket;
        parseHttpRequest();
        if(StrUtil.isEmpty(requestString))
            return;
        parseUri();
    }

    private void parseHttpRequest() throws IOException {
        InputStream is = this.socket.getInputStream();
        byte[] bytes = MiniBrowser.readBytes(is);
        requestString = new String(bytes, "utf-8");
    }

    private void parseUri() {
        String temp;

        temp = StrUtil.subBetween(requestString, " ", " ");
        if (!StrUtil.contains(temp, '?')) {
            uri = temp;
            return;
        }
        temp = StrUtil.subBefore(temp, '?', false);
        uri = temp;
    }

    public String getUri() {
        return uri;
    }

    public String getRequestString(){
        return requestString;
    }

}

package cn.how2j.diytomcat;

import cn.how2j.diytomcat.http.Request;
import cn.hutool.core.util.NetUtil;

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

public class Bootstrap {

    public static void main(String[] args) {

        try {
            int port = 18080;

            if(!NetUtil.isUsableLocalPort(port)) {
                System.out.println(port +" 端口已经被占用了，排查并关闭本端口的办法请用：\r\nhttps://how2j.cn/k/tomcat/tomcat-portfix/545.html");
                return;
            }
            ServerSocket ss = new ServerSocket(port);

            while(true) {
                Socket s =  ss.accept();
                Request request = new Request(s);
                System.out.println("浏览器的输入信息： \r\n" + request.getRequestString());
                System.out.println("uri:" + request.getUri());

                OutputStream os = s.getOutputStream();
                String response_head = "HTTP/1.1 200 OK\r\n" + "Content-Type: text/html\r\n\r\n";
                String responseString = "Hello DIY Tomcat from how2j.cn";
                responseString = response_head + responseString;
                os.write(responseString.getBytes());
                os.flush();
                s.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}