java web实现简单聊天室

目标

servlet、jsp实现简单聊天室，用户通过浏览器登录后进入聊天室，可发送消息进行群聊，点击聊天信息框中的用户名可实现拍一拍功能。

基础知识

ServletContext上下文对象：一直存在于服务器，存储公有、 共享数据Session会话对象：独立

实现思路

1.登录页面 login.jsp 输入昵称

2.编写一个LoginSevlet，处理登录提交的昵称，保存登录昵称到session（会话变量）若昵称合法 if(nickname.length()!=0)，跳转到聊天室，不合法回到登录页面

3.编写聊天室页面chatroom.jsp ，是一个框架，把多个页面集成到一个页面中

<iframe src='https://www.haobala.com/bcjs/message.jsp' height='70%'> </iframe><iframe src='https://www.haobala.com/bcjs/input.jsp' height='25%'> </iframe>

4.聊天内容显示message.jsp，不断自动刷新标签内设置响应头,用${上下文变量}显示聊天内容

<meta http-equiv='refresh' content='1'>

5.input.jsp（不刷新）输入聊天内容文本框text，点击发送聊天内容按钮时，将把文本框的聊天信息提交给ChatServlet处理。下方有超链接可退出聊天室。

<a href='https://www.haobala.com/bcjs/login.jsp' target='_top'>退出聊天室</a>

6.ChatServlet：检测聊天信息合法性，把聊天信息加入到ServletContext变量（字符串）中，（每次都将xx:xxxx加入上下文字符串）判断是否存在该变量，存在则直接读取现有聊天内容，把数据加入进去后，重新写回上下文变量

7.实现拍一拍功能（目的：学习如何进行链接操作）每个人名做成一个链接，访问某一个servlet，该servlet可以在聊天信息（上下文变量）里添加一行，xx拍了yyy一下，跳转回message.jsp问题：链接里应该包含yyy参数，servlet？nick=yyy

say = '<a href=’NickServlet?nickname='+nickname+'’target=’_parent’>'+nickname+'</a>'+':'+text;

8.多人聊天实现：多种类型浏览器

关键代码

login.jsp

昵称：<input type='text' name='nickname'/><br> <br><br><input type='submit' value='登录'/><input type='reset' value='取消'/>

input.jsp

<form action='input.do' method='post'> <input type='text' size='50' name='text'/> <input type='submit' value='发送'><br><br><br><br> <a href='https://www.haobala.com/bcjs/login.jsp' rel='external nofollow' rel='external nofollow' target='_top'>退出聊天室</a></form>

message.jsp

<h3>一起来聊天吧</h3>${says}

LoginServlet.java

package chatting;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.io.PrintWriter;@WebServlet(name = 'LoginServlet2',urlPatterns = {'/login.do'})public class LoginServlet2 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //避免乱码 response.setContentType('text/html;charset=utf-8'); request.setCharacterEncoding('utf-8'); //nickname保存用户昵称 String nickname = request.getParameter('nickname'); //nickname存储到session变量中 HttpSession session = request.getSession(); session.setAttribute('nickname',nickname); //对nickname进行合法性判断 if(nickname.length()!=0){ //昵称合法，则进入聊天室页面 request.getRequestDispatcher('/chatroom.jsp').forward(request,response); } else{ //昵称不合法，返回登陆页面 request.getRequestDispatcher('/login.jsp').forward(request,response); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { }}

ChatServlet.java

package chatting;import javax.servlet.RequestDispatcher;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.util.Vector;@WebServlet(name = 'ChatServlet',urlPatterns = '/input.do')public class ChatServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //防止乱码 request.setCharacterEncoding('utf-8'); response.setContentType('text/html;charset=utf-8'); HttpSession session = request.getSession(); String text = request.getParameter('text'); //text存储聊天信息，并进行合法性判断 if (text.length()!=0) { String say =new String(); //获取session中的昵称 String nickname = (String)session.getAttribute('nickname'); //将昵称作为链接，并传参 say = '<a href=’NickServlet?nickname='+nickname+'’target=’_parent’>'+nickname+'</a>'+':'+text; String says = new String(); //将昵称和聊天信息一起放在上下文变量 ServletContext context = getServletContext(); if(context.getAttribute('says')!=null){ says = context.getAttribute('says') + say + '<br>'; } else{ says = say + '<br>'; } context.setAttribute('says', says); request.setAttribute('says', says); } //转发 RequestDispatcher dispatcher = request.getRequestDispatcher('/input.jsp'); dispatcher.forward(request, response); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { }}

NickServlet.java

package chatting;import javax.servlet.RequestDispatcher;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.io.PrintWriter;@WebServlet(name = 'NickServlet',urlPatterns = '/NickServlet')public class NickServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType('text/html;charset=UTF-8'); request.setCharacterEncoding('utf-8'); //将拍一拍放到上下文变量says中 一起输出 HttpSession session = request.getSession(); //nickname存储当前用户昵称 String nickname = (String)session.getAttribute('nickname'); //name存储连接中传递的参数，即被拍的用户昵称 String name = java.net.URLDecoder.decode(request.getParameter('nickname'),'UTF-8'); String pick = nickname+'拍了拍'+name+'<br>'; ServletContext context = request.getServletContext(); String says = context.getAttribute('says')+pick; context.setAttribute('says',says); RequestDispatcher dispatcher = request.getRequestDispatcher('/chatroom.jsp'); dispatcher.forward(request, response); }}

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