我的要求是管理員應該向所有登錄的用戶發送數據。我有一個servlet第一個用戶發送登錄HTTP請求並獲取來自servlet現在會話的登錄成功響應爲此用戶啓動。類似地其他用戶登錄。現在管理員這也是一個用戶可以登錄並看到兩個用戶user1和user2登錄。管理員應該向所有登錄的用戶發送數據。 Servlet應該向沒有用戶HTTP請求的用戶推送數據。請注意會話期間用戶不會發送任何其他HTTP請求。相反,彗星的如何將數據從servlet發送到所有登錄的用戶
我試圖存儲每個響應OBJ的登錄用戶,然後再使用obj是否曾經試圖發佈數據傳回用戶,但沒有奏效。
請檢查下面的代碼:LoginServlet.java
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
ServletContext sc;
protected ArrayList<HttpServletResponse> connections = new ArrayList<HttpServletResponse>();
public LoginServlet() {
super();
}
public void init() throws ServletException {
super.init();
sc = getServletContext();
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
synchronized (connections) {
connections.add(response);
}
ServletContext sc = getServletContext();
Integer x = (Integer) sc.getAttribute("hit");
if (x == null)
x = 1;
else
x++;
sc.setAttribute("hit", x);
String username = request.getParameter("username");
String password = request.getParameter("password");
HttpSession session = request.getSession(true);
session.setAttribute("username", username);
session.setAttribute("password", password);
response.setContentType("text/html");
ArrayList<LoggedInUser> loggedInUsers = (ArrayList<LoggedInUser>) sc
.getAttribute("users");
if (loggedInUsers == null) {
System.out.println("loggedInUsers creates");
loggedInUsers = new ArrayList<LoggedInUser>();
}
loggedInUsers.add(new LoggedInUser(username, password));
sc.setAttribute("users", loggedInUsers);
PrintWriter out = response.getWriter();
System.out.println("loggedInUsers ==>" + loggedInUsers.size());
if (username != null && username.equals("admin")) {
out.println("Admin Login Success");
ServletContext scx = getServletContext();
Integer xx = (Integer) scx.getAttribute("hit");
out.println("<H1>Users visited " + xx + "</h1>");
loggedInUsers = (ArrayList<LoggedInUser>) sc.getAttribute("users");
for (int i = 0; i <= loggedInUsers.size() - 1; i++) {
LoggedInUser LoggedInUser = loggedInUsers.get(i);
out.println(LoggedInUser.getmUsername()+ "<br>");
}
for (int i = 0; i < connections.size(); i++) {
try {
LoggedInUser LoggedInUser = loggedInUsers.get(i);
PrintWriter writer = connections.get(i).getWriter();
System.out.println("inside loope " + i + "\n" + writer);
writer.println("MESSAGE FROM ADMIN HERE" + "<br>");
writer.flush();
writer.close();
} catch (IOException e) {
log("IOExeption sending message", e);
}
}
} else {
out.println("Welcome " + username + " Login Success");
}
}
}
只要在ArrayList中存儲的RESP OBJ用戶登錄。
synchronized (connections) {
connections.add(response);
}
然後使用該obj得到了printwriter obj。
PrintWriter writer = connections.get(i).getWriter();
問題:
- 如何一個具體的MSG發送給所有已登錄的用戶?
- 沒有彗星可以實現嗎?
如果有任何問題,我已經完成並幫助其他建議,請更正代碼。感謝
使用電子郵件:d –
嘿,你用什麼java的演示技術? Java-Server-Faces,Wicket,JSP,Struts,Spring? –
@ peter不能存儲響應obj並使用該obj發送消息嗎? – user1537457