benbai123/Chat.java

## Chat.java
package test.jsp.simplechat;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONArray;


public class Chat extends HttpServlet {
  /**
	 *
	 */
	private static final long serialVersionUID = 113880057049845876L;
	// message map, mapping user UID with a message list
	private static Map<String, List<String>> _chat = new HashMap<String, List<String>>();
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		String action = req.getParameter("action");
		// send message
		if ("send".equals(action)) {
			// get param with UTF-8 enconding
			String msg = new String(req.getParameter("msg").getBytes("ISO-8859-1"), "UTF-8");
			String uid = (String)req.getSession().getAttribute("UID");
			for (String s : _chat.keySet()) {
				if (!s.equals(uid)) {
					synchronized (_chat.get(s)) {
						// put message to any other user's msg list
						_chat.get(s).add(uid+" said: "+msg);
					}
				}
			}
		} else if ("get".equals(action)) { // get message
			String uid = (String)req.getSession().getAttribute("UID");
			if (uid == null)
				resp.sendError(HttpServletResponse.SC_BAD_REQUEST);
			List<String> l = _chat.get(uid);
			synchronized (l) {
				if (l.size() > 0) {
					// for UTF-8 chars
					resp.setCharacterEncoding("UTF-8");
					PrintWriter out = resp.getWriter();
					JSONArray jsna = new JSONArray();
					// add all msg to json array and clear list
					while (l.size() > 0)
						jsna.add(l.remove(0));

					out.println(jsna);
					out.close();
				}
			}
		}
	}
	public static Map<String, List<String>> getChatMap () {
		return _chat;
	}
}

## chat.jsp
<%@ page isErrorPage="true" language="java"
  contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page isELIgnored ="false" %>
<!-- Redirect to index.jsp if no UID -->
<c:if test="${UID == null}">
	<c:redirect url="index.jsp" />
</c:if>
<html>
	<head>
		<meta http-equiv="Content-Type"
			content="text/html; charset=UTF-8"/>
		<title>Login page</title>
		<link href="css/chat.css" rel="stylesheet" type="text/css">
		<script type="text/javascript" src="js/chat.js"></script>
	</head>
	<body>
		<form action="logout.go" method="post">
			<div>This is chat page</div>
			<div>Type message then press ENTER key to send message</div>
			<div>Click logout to return the login page</div>
			<div>Your name: <span id="uid">${UID}</span></div>
			<div id="content" class="content"></div>
			<div>
				<!-- listen to keyup to send message if enter pressed -->
				<textarea class="msg-input" onkeyup="chat.dokeyup(event);">input text here</textarea>
			</div>
			<input type="submit" value="logout" />
		</form>
	</body>
</html>

## index.jsp
<%@ page isErrorPage="true" language="java"
  contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page isELIgnored ="false" %>
<html>
	<head>
		<meta http-equiv="Content-Type"
			content="text/html; charset=UTF-8"/>
		<title>Login page</title>
	</head>
	<body>
		<form action="login.go" method="post">
			<span>Type a name then press login to enter chat room</span>
			<input id="userId" type="text" value="Your ID" name="uid" />
			<input type="submit" value="login"/>
		</form>
	</body>
</html>

## Login.java
package test.jsp.simplechat;

import java.io.IOException;
import java.util.*;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class Login extends HttpServlet {
  /**
	 *
	 */
	private static final long serialVersionUID = -8873939883201271898L;

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
		String uid = new String(req.getParameter("uid").getBytes("ISO-8859-1"), "UTF-8");
		String newUid = uid;
		int i = 2;
		Map<String, List<String>> chat = Chat.getChatMap();
		synchronized (chat) {
			// prevent uid conflict
			if ("you".equalsIgnoreCase(newUid))
				newUid = uid + i++;
			while (chat.containsKey(newUid))
				newUid = uid + i++;
			uid = newUid;
			chat.put(uid, new ArrayList<String>());
		}
		req.getSession().setAttribute("UID", uid);
		resp.sendRedirect("chat.jsp");
	}
}

## Logout.java
package test.jsp.simplechat;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


// practice: invalidate session
public class Logout extends HttpServlet {
  /**
	 *
	 */
	private static final long serialVersionUID = -6175876557872938832L;

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
		req.getSession().invalidate();
		resp.sendRedirect("index.jsp");
	}
}

## web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
	version="2.4">
	<servlet>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>test.jsp.simplechat.Login</servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/login.go</url-pattern>
	</servlet-mapping>
	<servlet>
		<servlet-name>ChatServlet</servlet-name>
		<servlet-class>test.jsp.simplechat.Chat</servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>ChatServlet</servlet-name>
		<url-pattern>/chat.do</url-pattern>
	</servlet-mapping>
	<servlet>
		<servlet-name>Logout</servlet-name>
		<servlet-class>test.jsp.simplechat.Logout</servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>Logout</servlet-name>
		<url-pattern>/logout.go</url-pattern>
	</servlet-mapping>
</web-app>
	package test.jsp.simplechat;

	import java.io.IOException;
	import java.io.PrintWriter;
	import java.util.*;

	import javax.servlet.ServletException;

	import javax.servlet.http.HttpServlet;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;

	import net.sf.json.JSONArray;


	public class Chat extends HttpServlet {
	/**
	*
	*/
	private static final long serialVersionUID = 113880057049845876L;
	// message map, mapping user UID with a message list
	private static Map<String, List<String>> _chat = new HashMap<String, List<String>>();
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
	throws ServletException, IOException {
	req.setCharacterEncoding("UTF-8");
	String action = req.getParameter("action");
	// send message
	if ("send".equals(action)) {
	// get param with UTF-8 enconding
	String msg = new String(req.getParameter("msg").getBytes("ISO-8859-1"), "UTF-8");
	String uid = (String)req.getSession().getAttribute("UID");
	for (String s : _chat.keySet()) {
	if (!s.equals(uid)) {
	synchronized (_chat.get(s)) {
	// put message to any other user's msg list
	_chat.get(s).add(uid+" said: "+msg);
	}
	}
	}
	} else if ("get".equals(action)) { // get message
	String uid = (String)req.getSession().getAttribute("UID");
	if (uid == null)
	resp.sendError(HttpServletResponse.SC_BAD_REQUEST);
	List<String> l = _chat.get(uid);
	synchronized (l) {
	if (l.size() > 0) {
	// for UTF-8 chars
	resp.setCharacterEncoding("UTF-8");
	PrintWriter out = resp.getWriter();
	JSONArray jsna = new JSONArray();
	// add all msg to json array and clear list
	while (l.size() > 0)
	jsna.add(l.remove(0));

	out.println(jsna);
	out.close();
	}
	}
	}
	}
	public static Map<String, List<String>> getChatMap () {
	return _chat;
	}
	}
	<%@ page isErrorPage="true" language="java"
	contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
	<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
	<%@ page isELIgnored ="false" %>
	<!-- Redirect to index.jsp if no UID -->
	<c:if test="${UID == null}">
	<c:redirect url="index.jsp" />
	</c:if>
	<html>
	<head>
	<meta http-equiv="Content-Type"
	content="text/html; charset=UTF-8"/>
	<title>Login page</title>
	<link href="css/chat.css" rel="stylesheet" type="text/css">
	<script type="text/javascript" src="js/chat.js"></script>
	</head>
	<body>
	<form action="logout.go" method="post">
	<div>This is chat page</div>
	<div>Type message then press ENTER key to send message</div>
	<div>Click logout to return the login page</div>
	<div>Your name: <span id="uid">${UID}</span></div>
	<div id="content" class="content"></div>
	<div>
	<!-- listen to keyup to send message if enter pressed -->
	<textarea class="msg-input" onkeyup="chat.dokeyup(event);">input text here</textarea>
	</div>
	<input type="submit" value="logout" />
	</form>
	</body>
	</html>
	<?xml version="1.0" encoding="ISO-8859-1"?>
	<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
	version="2.4">
	<servlet>
	<servlet-name>LoginServlet</servlet-name>
	<servlet-class>test.jsp.simplechat.Login</servlet-class>
	<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
	<servlet-name>LoginServlet</servlet-name>
	<url-pattern>/login.go</url-pattern>
	</servlet-mapping>
	<servlet>
	<servlet-name>ChatServlet</servlet-name>
	<servlet-class>test.jsp.simplechat.Chat</servlet-class>
	<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
	<servlet-name>ChatServlet</servlet-name>
	<url-pattern>/chat.do</url-pattern>
	</servlet-mapping>
	<servlet>
	<servlet-name>Logout</servlet-name>
	<servlet-class>test.jsp.simplechat.Logout</servlet-class>
	<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
	<servlet-name>Logout</servlet-name>
	<url-pattern>/logout.go</url-pattern>
	</servlet-mapping>
	</web-app>