jd

import java.util.regex.Pattern;
import java.util.regex.Matcher;
import java.util.Scanner;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.Socket;

public class Main {
	//Regex
	static String pattern_str = "^http://([^/:]*):?(\\d{1,5})?/(.*)$";
	
	public static void main(String args[]){
		Pattern pattern = Pattern.compile(pattern_str);  //pattern_str 轉換成   Regex規則
		Scanner scan = new Scanner(System.in);
		Scanner inputFile;  //使指標去除HEADER
		String input = scan.next();
		
		Matcher matcher = pattern.matcher(input);  //匹配結果
		if(matcher.matches()){  //匹配結果符合
			String hostname = matcher.group(1);  //pattern_str中第一個()內容 = hostname
			String port_s = matcher.group(2);  //pattern_str中第二個()內容 = port
			String filename = matcher.group(3);  //pattern_str中第三個()內容 = filename
			
			int port = 80;  //預設port
			if(port_s != null && !port_s.equals("")){
				port = Integer.parseInt(port_s);
			}
			System.out.println("host = " + hostname);
			System.out.println("port = " + port);
			
			String header = String.format(
				"GET %s HTTP/1.1\r\nHost: %s\r\n\r\n",
				filename,
				hostname);
			/*
				GET {filename} HTTP/1.1\r\n
				Host: {hostname}\r\n
				\r\n
			*/
			
			try{
				Socket sock = new Socket(hostname, port);
				byte[] b = new byte[1024];  //接收byte的buffer
				int len = 0;  //接收的資料長度
				String[] a = filename.split("/");
				FileOutputStream out_file = new FileOutputStream(a[a.length-1]);  //找出最後一個"/"後的名稱為檔案名
				// 送出 the header from our input
				BufferedOutputStream out = new BufferedOutputStream(sock.getOutputStream());
				out.write(header.getBytes());
				out.flush();
				
				//將寫入的檔案指標先用Scanner.nextLine()移動一次，則剛好可以去除HEADER
				inputFile = new Scanner(sock.getInputStream());
				inputFile.nextLine();  //It's magic!
				
				//接收從server回傳的檔案
				BufferedInputStream in = new BufferedInputStream(sock.getInputStream());
				while((len = in.read(b)) > 0){  //每次回傳len個bytes 直到沒有回傳為止
					out_file.write(b, 0, len);
					// write the b to the file
				}
				//關閉
				out_file.close();
				in.close();
				out.close();
				sock.close();
				System.out.println("The download is finished.");
			
			}catch(IOException e){
				e.printStackTrace();
				System.out.println("Error!");
			}
			
		}else{  //沒有匹配結果
			System.out.println("No match.");
		}
	}
}



// curl-like