java web實現簡單聊天室
目標
servlet、jsp實現簡單聊天室,使用者通過瀏覽器登入後進入聊天室,可傳送訊息進行群聊,點選聊天資訊框中的使用者名稱可實現拍一拍功能。
基礎知識
- 資料的存取 setAttribute / getAttribute
- request請求物件 :有效時間短
ServletContext上下文物件:一直存在於伺服器,儲存公有、 共享資料
Session會話物件:獨立
- 網站預設頁面一般是index.jsp
實現思路
1.登入頁面 login.jsp 輸入暱稱
2.編寫一個LoginSevlet,處理登入提交的暱稱,儲存登入暱稱到session(會話變數)
若暱稱合法 if(nickname.length()!=0),跳轉到聊天室,不合法回到登入頁面
3.編寫聊天室頁面chatroom.jsp ,是一個框架,把多個頁面整合到一個頁面中
<iframe src="message.jsp" width="100%" height="70%"> </iframe> <iframe src="input.jsp" width="100%" height="25%"> </iframe>
4.聊天內容顯示message.jsp,不斷自動重新整理標籤內設定響應頭,用${上下文變數}顯示聊天內容
<meta http-equiv="refresh" content="1">
5.input.jsp(不重新整理)輸入聊天內容文字框text,點擊發送聊天內容按鈕時,將把文字框的聊天資訊提交給ChatServlet處理。下方有超連結可退出聊天室。
<a href="login.jsp" target="_top">退出聊天室</a>
6.ChatServlet:檢測聊天資訊合法性,把聊天資訊加入到ServletContext變數(字串)中,(每次都將xx:xxxx加入上下文字串)
判斷是否存在該變數,存在則直接讀取現有聊天內容,把資料加入進去後,重新寫回上下文變數
7.實現拍一拍功能(目的:學習如何進行連結操作)
每個人名做成一個連結,訪問某一個servlet,該servlet可以在聊天資訊(上下文變數)裡新增一行,xx拍了yyy一下,跳轉回message.jsp
問題:連結裡應該包含yyy引數,servlet?nick=yyy
say = "<a href='NickServlet?nickname="+nickname+"'target='_parent'>"+nickname+"</a>"+":"+text;
8.多人聊天實現:多種型別瀏覽器
關鍵程式碼
login.jsp
暱稱:<input type="text" name="nickname"/><br> <br><br> <input type="submit" value="登入"/> <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="傳送"><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
<h3>一起來聊天吧</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 { //避免亂碼 response.setContentType("text/html;charset=utf-8"); request.setCharacterEncoding("utf-8"); //nickname儲存使用者暱稱 String nickname = request.getParameter("nickname"); //nickname儲存到session變數中 HttpSession session = request.getSession(); session.setAttribute("nickname",nickname); //對nickname進行合法性判斷 if(nickname.length()!=0){ //暱稱合法,則進入聊天室頁面 request.getRequestDispatcher("/chatroom.jsp").forward(request,response); } else{ //暱稱不合法,返回登陸頁面 request.getRequestDispatcher("/login.jsp").forward(request,response); } } protected void doGet(HttpServletRequest request,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,IOException { //防止亂碼 request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); HttpSession session = request.getSession(); String text = request.getParameter("text"); //text儲存聊天資訊,並進行合法性判斷 if (text.length()!=0) { String say =new String(); //獲取session中的暱稱 String nickname = (String)session.getAttribute("nickname"); //將暱稱作為連結,並傳參 say = "<a href='NickServlet?nickname="+nickname+"'target='_parent'>"+nickname+"</a>"+":"+text; String says = new String(); //將暱稱和聊天資訊一起放在上下文變數 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); } //轉發 RequestDispatcher dispatcher = request.getRequestDispatcher("/input.jsp"); dispatcher.forward(request,response); } protected void doGet(HttpServletRequest request,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,IOException { } protected void doGet(HttpServletRequest request,IOException { response.setContentType("text/html;charset=UTF-8"); request.setCharacterEncoding("utf-8"); //將拍一拍放到上下文變數says中 一起輸出 HttpSession session = request.getSession(); //nickname儲存當前使用者暱稱 String nickname = (String)session.getAttribute("nickname"); //name儲存連線中傳遞的引數,即被拍的使用者暱稱 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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