JSP + AJAX 打造簡單聊天室

来源：互联网发布：应用商店mac系统镜像编辑：程序博客网时间：2024/05/16 06:03

本文代碼下載地址：http://download.csdn.net/source/798197

一個簡單的聊天室程式，但基本包含了簡單的AJAX的使用方法，可以做為簡單的Demo用來學習。

整個程式包含三個文件，頁面文件chat.html,後臺處理的Servlet文件Chat.java以及簡單的用戶資料的UserSessionListener.java類。其中chat.html用于接受用戶輸入，並將接收資料傳給後臺Servlet處理，UserSessionListener主要用於登入和登出時用戶列表及提示信息的處理。

chat.html如下：

<html>

<head>

var HttpRequest;

var url = "Chat";

function getRequest(){

if(window.XMLHttpRequest){

return(new XMLHttpRequest());

}else if(window.ActiveXObject){

try{

return(new ActiveXObject("Msxm12.XMLHTTP"));

}catch(e){

try{

return(new ActiveXObject("Microsoft.XMLHTTP"));

}catch(e){}

}

function sendRequest(){

if(document.getElementById("txtMessage").value.length<=0){

return false;

}

HttpRequest = getRequest();

//HttpRequest.onreadystatechange = getMessage;

HttpRequest.open("POST", url, true);

HttpRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

var msg;

msg = "Action=AddMessage&Message=" + escape(document.getElementById("txtMessage").value);

HttpRequest.send(msg);

document.getElementById("txtMessage").value = "";

//document.getElementById("txtMessage").focus();

}

function DisplayMessage(){

if(HttpRequest.readyState == 4 && HttpRequest.status == 200){

//alert("abd");

//alert(HttpRequest.responseText);

var messages;

//alert(HttpRequest.responseText);

messages = HttpRequest.responseText.split("!@#");

//document.writeln(messages[0]);

//document.writeln(messages[1]);

document.getElementById("Messages").innerHTML = messages[0];

document.getElementById("userList").innerHTML = "User List <br>" + messages[1];

//document.getElementById

}

function logout(){

HttpRequest = getRequest();

HttpRequest.open("POST", url, true);

HttpRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

var msg;

msg = "Action=Logout";

HttpRequest.send(msg);

}

function getMessage(){

HttpRequest = getRequest();

HttpRequest.onreadystatechange = DisplayMessage;

HttpRequest.open("POST", url, true);

HttpRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

var msg;

msg = "Action=GetMessage";

HttpRequest.send(msg);

document.all.txtMessage.focus();

}

function login(){

HttpRequest = getRequest();

var WshNetwork = new ActiveXObject("WScript.Network");

HttpRequest.open("POST", url, true);

HttpRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

var msg;

msg = "Action=Login&UserName=" + WshNetwork.UserName;

HttpRequest.send(msg);

setInterval('getMessage();', 1000);

}

function chkSubmit(e){

if(window.event){

var keyNumber = e.keyCode;

if(keyNumber == 13){

sendRequest();

}

</script>

</head>

<table>

</tr>

</table>

</form>

</body>

</html>

用於處理頁面提交信息的Servlet Chat.java代碼如下：

import java.io.IOException;

import java.io.PrintWriter;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.LinkedList;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import moon.UserSessionListener;

/**

* Servlet implementation class for Servlet: Chat

public class Chat extends javax.servlet.http.HttpServlet implements

javax.servlet.Servlet {

static final long serialVersionUID = 1L;

private String userName = "";

* (non-Java-doc)

* @see javax.servlet.http.HttpServlet#HttpServlet()

public Chat() {

super();

}

private String getNow(){

Date date = new Date();

SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

return df.format(date);

}

* (non-Java-doc)

* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request,

* HttpServletResponse response)

@SuppressWarnings("unchecked")

protected void doGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

String action = request.getParameter("Action");

if (action == null) {

} else if (action.equals("GetMessage")) {

PrintWriter out = response.getWriter();

out.print(getMessages() + "!@#" + getOnlineUsers());

} else if (action.equals("AddMessage")) {

String message = request.getParameter("Message");

userName = ((UserSessionListener) request.getSession()

.getAttribute("UserName")).toString();

addMessage(getNow() + " " + userName + " Says: " + message);

}else if(action.equals("Logout")){

request.getSession().removeAttribute("UserName");

}else if(action.equals("Login")){

request.getSession().setAttribute("UserName", new UserSessionListener(request.getParameter("UserName")));

}

// TODO Auto-generated method stub

}

* (non-Java-doc)

* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request,

* HttpServletResponse response)

protected void doPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

// TODO Auto-generated method stub

}

@SuppressWarnings("unchecked")

private String getMessages() {

String result = null;

ServletContext application = getServletContext();

LinkedList<String> messages = (LinkedList<String>) application

.getAttribute("ChatMessage");

if (messages == null) {

result = "";

} else {

StringBuilder sb = new StringBuilder("");

for (String tmp : messages) {

sb.append(tmp);

sb.append("<br>");

}

result = sb.toString();

}

return result;

}

@SuppressWarnings("unchecked")

private String getOnlineUsers() {

String result;

LinkedList<String> onlineUsers = (LinkedList<String>)getServletContext().getAttribute("UserList");

if (onlineUsers == null) {

result = "";

} else {

StringBuilder users = new StringBuilder("");

for (String tmp : onlineUsers) {

users.append(tmp);

users.append("<br>");

}

result = users.toString();

}

return result;

}

@SuppressWarnings("unchecked")

private void addMessage(String message) {

ServletContext application = getServletContext();

synchronized (application) {

LinkedList<String> messages = (LinkedList<String>) application

.getAttribute("ChatMessage");

if (messages == null) {

messages = new LinkedList<String>();

}

if (messages.size() > 30) {

messages.removeFirst();

}

messages.add(message);

application.setAttribute("ChatMessage", messages);

}

public void destroy() {

super.destroy();

}

用于做用戶登陸，登出處理類UserSessionListener代碼如下：

import javax.servlet.ServletContext;

import javax.servlet.http.HttpSessionBindingEvent;

import javax.servlet.http.HttpSessionBindingListener;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.LinkedList;

public class UserSessionListener implements HttpSessionBindingListener {

private String userName;

public UserSessionListener(String userName) {

super();

this.userName = userName;

}

private String getNow(){

Date date = new Date();

SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

return df.format(date);

}

@SuppressWarnings("unchecked")

public void valueBound(HttpSessionBindingEvent arg0) {

// TODO Auto-generated method stub

arg0.getSession().setMaxInactiveInterval(120);

ServletContext application = arg0.getSession().getServletContext();

synchronized (application) {

LinkedList<String> userList = (LinkedList<String>) application

.getAttribute("UserList");

if (userList == null) {

userList = new LinkedList<String>();

}

userList.add(userName);

application.setAttribute("UserList", userList);

LinkedList<String> messages = (LinkedList<String>) application

.getAttribute("ChatMessage");

if (messages == null) {

messages = new LinkedList<String>();

}

messages.add(getNow() + " " + userName + " Login...");

application.setAttribute("ChatMessage", messages);

}

@SuppressWarnings("unchecked")

public void valueUnbound(HttpSessionBindingEvent arg0) {

// TODO Auto-generated method stub

ServletContext application = arg0.getSession().getServletContext();

synchronized (application) {

LinkedList<String> userList = (LinkedList<String>) application

.getAttribute("UserList");

userList.remove(userName);

application.setAttribute("UserList", userList);

LinkedList<String> messages = (LinkedList<String>) application

.getAttribute("ChatMessage");

if (messages == null) {

messages = new LinkedList<String>();

}

messages.add(getNow() + " " + userName + " Logout...");

application.setAttribute("ChatMessage", messages);

}

/**

* @return the userName

public String getUserName() {

return userName;

}

/**

* @param userName

* the userName to set

public void setUserName(String userName) {

this.userName = userName;

}

public String toString() {

return this.userName;

}

其中UserSessionListener類實現了HttpSessionBingdingListener接口，以便于在用戶登入和登出時實現用戶列表的更新。