servlet 之间通信时出现空指针异常
我在一个servlet中有登录代码：LoginGtalkServlet..
XMPPConnection connection;
//@see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String userName = request.getParameter("username");
String password = request.getParameter("password");
System.out.println(userName);
System.out.println(password);
//ProxyInfo proxyInfo = new
ConnectionConfiguration config = new ConnectionConfiguration("talk.google.com",5222,"gmail.com");
connection = new XMPPConnection(config);
config.setSASLAuthenticationEnabled(false);
try {
connection.connect();
} catch (XMPPException e) {
e.printStackTrace();
}
try {
connection.login(userName, password);
} catch (XMPPException e) {
e.printStackTrace();
}
boolean status=connection.isAuthenticated();
if(status==true)
{
System.out.println("Success");
response.sendRedirect("GetRoster");
}
else
{
response.sendRedirect("Loginfailed.html");
}
并且我的GetRosterServlet有用于检索名册列表的代码
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
Roster roster = connection.getRoster();
Collection<RosterEntry> entries = roster.getEntries();
for (RosterEntry r : entries) {
String user = r.getUser();
String name = r.getName();
System.out.println(name + user);
}
roster.addRosterListener(new RosterListener() {
// Ignored events public void entriesAdded(Collection<String>
// addresses) {}
public void entriesDeleted(Collection<String> addresses) {
}
public void entriesUpdated(Collection<String> addresses) {
}
public void presenceChanged(Presence presence) {
System.out.println("Presence changed: " + presence.getFrom()
+ " " + presence);
}
@Override
public void entriesAdded(Collection<String> arg0) {
}
});
}
现在问题是我的GetRosterServlet没有被告知我已经登录到Gtalk..ie LoginGtalkServlet没有与GetRosterServlet通信，因此没有连接。 getRoster() 抛出空指针异常...
我如何让名册 servlet 知道用户已登录到 gtalk 并因此获得好友列表
I have login code in one servlet:LoginGtalkServlet..
XMPPConnection connection;
//@see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String userName = request.getParameter("username");
String password = request.getParameter("password");
System.out.println(userName);
System.out.println(password);
//ProxyInfo proxyInfo = new
ConnectionConfiguration config = new ConnectionConfiguration("talk.google.com",5222,"gmail.com");
connection = new XMPPConnection(config);
config.setSASLAuthenticationEnabled(false);
try {
connection.connect();
} catch (XMPPException e) {
e.printStackTrace();
}
try {
connection.login(userName, password);
} catch (XMPPException e) {
e.printStackTrace();
}
boolean status=connection.isAuthenticated();
if(status==true)
{
System.out.println("Success");
response.sendRedirect("GetRoster");
}
else
{
response.sendRedirect("Loginfailed.html");
}
And my GetRosterServlet has the code for retreving the roster list
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
Roster roster = connection.getRoster();
Collection<RosterEntry> entries = roster.getEntries();
for (RosterEntry r : entries) {
String user = r.getUser();
String name = r.getName();
System.out.println(name + user);
}
roster.addRosterListener(new RosterListener() {
// Ignored events public void entriesAdded(Collection<String>
// addresses) {}
public void entriesDeleted(Collection<String> addresses) {
}
public void entriesUpdated(Collection<String> addresses) {
}
public void presenceChanged(Presence presence) {
System.out.println("Presence changed: " + presence.getFrom()
+ " " + presence);
}
@Override
public void entriesAdded(Collection<String> arg0) {
}
});
}
Now the isssue is my GetRosterServlet is not informed that I haved logged into Gtalk..i.e LoginGtalkServlet is not communicating with GetRosterServlet and hence connection.getRoster() is throwing Null pointer exception...
How do I let the roster servlet know that the user is logged into gtalk and hence get the friends list
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请注意，我不熟悉 XMPP/GTalk。
当您在
LoginGtalkServlet中登录时，是否有可能返回某种会话 ID？如果是这样，您可以将其作为查询参数或 POST 正文放入重定向 URL 中，然后 GetRosterServlet 可以从请求中提取会话 ID 并将其用于 Gtalk该会话 ID。（注意：我刚刚所做的编辑只是为了修复一些错误的语法。没有实质性的更改。）
Note that I'm not familiar with XMPP/GTalk.
When you log in to it in
LoginGtalkServlet, is it possible for you to be handed back some sort of session ID? If so, you could put that into the redirect URL as a query parameter or in a POST body and thenGetRosterServletcould extract the session ID fromrequestand use it to Gtalk via that session ID.(Note: the edit I just made was just to fix some bad grammar. No substantive changes.)
您可以将连接对象保存在会话属性中。
并可以通过使用
session.getAttribute("connection");You can save the connection object in the session attribute.
And can get by using
session.getAttribute("connection");