package com.liuxin;

//WebServer.java 用JAVA編寫Web服務器

import java.io.*;

import java.net.*;

public class WebServer {

	public static void main(String args[]) {

		int i = 1, PORT = 8080;

		ServerSocket server = null;

		Socket client = null;

		try {

			server = new ServerSocket(PORT);

System.out.println("Web Server is listening on port "
					+ server.getLocalPort());

			for (;;) {                    //相當于while(true)循環；

				client = server.accept(); // 接受客戶機的連接請求

				new ConnectionThread(client, i).start();

				i++;

			}

		} catch (Exception e) {
			System.out.println(e);
		}

	}

}

/* ConnnectionThread類完成與一個Web瀏覽器的通信 */

class ConnectionThread extends Thread {

	Socket client; // 連接Web瀏覽器的socket字

	int counter; // 計數器

	public ConnectionThread(Socket cl, int c) {

		client = cl;

		counter = c;

	}

	public void run() // 線程體

	{

		try {

			String destIP = client.getInetAddress().toString(); // 客戶機IP地址

			int destport = client.getPort(); // 客戶機端口號

			System.out.println("Connection " + counter + ":connected to "
					+ destIP + " on port " + destport + ".");

			PrintStream outstream = new PrintStream(client.getOutputStream());

			DataInputStream instream = new DataInputStream(client
					.getInputStream());

			String inline = instream.readLine(); // 讀取Web瀏覽器提交的請求信息

			System.out.println("Received:" + inline);

			if (getrequest(inline)) { // 如果是GET請求

				String filename = getfilename(inline);

				File file = new File(filename);

				if (file.exists()) { // 若文件存在，則將文件送給Web瀏覽器

					System.out.println(filename + " requested.");

					outstream.println("HTTP/1.0 200 OK");

					outstream.println("MIME_version:1.0");

					outstream.println("Content_Type:text/html");

					int len = (int) file.length();

					outstream.println("Content_Length:" + len);

					outstream.println("");

					sendfile(outstream, file); // 發送文件

					outstream.flush();

				} else { // 文件不存在時

					String notfound = "Error 404-file not found";

					outstream.println("HTTP/1.0 404 no found");

					outstream.println("Content_Type:text/html");

					outstream
							.println("Content_Length:" + notfound.length() + 2);

					outstream.println("");

					outstream.println(notfound);

					outstream.flush();

				}

			}

			long m1 = 1;

			while (m1 < 11100000) {
				m1++;
			} // 延時

			client.close();

		} catch (IOException e) {

			System.out.println("Exception:" + e);

		}

	}

	/* 獲取請求類型是否為“GET” */

	boolean getrequest(String s) {

		if (s.length() > 0)

		{

			if (s.substring(0, 3).equalsIgnoreCase("GET"))
				return true;

		}

		return false;

	}

	/* 獲取要訪問的文件名 */

	String getfilename(String s) {

		String f = s.substring(s.indexOf(' ') + 1);

		f = f.substring(0, f.indexOf(' '));

		try {

			if (f.charAt(0) == '/')

				f = f.substring(1);

		} catch (StringIndexOutOfBoundsException e) {

			System.out.println("Exception:" + e);

		}

		if (f.equals(""))
			f = "index.html";

		return f;

	}

	/* 把指定文件發送給Web瀏覽器 */

	void sendfile(PrintStream outs, File file) {

		try {

			DataInputStream in = new DataInputStream(new FileInputStream(file));

			int len = (int) file.length();

			byte buf[] = new byte[len];

			in.readFully(buf);

			outs.write(buf, 0, len);

			outs.flush();

			in.close();

		} catch (Exception e) {

			System.out.println("Error retrieving file.");

			System.exit(1);

		}

	}

}