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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="message.jsp" width="100%" height="70%"> </iframe> <iframe src="input.jsp" width="100%" 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="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="login.jsp" rel="external nofollow" rel="external nofollow" target="_top">退出聊天室</a> </form>
message.jsp
<h4>一起来聊天吧</h4>
${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);
}
}关于如何在java web项目中实现一个聊天功能就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
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