Java servlet之间通信时出现空指针异常
我在一个servlet中有登录代码:LoginGtalkServletJava servlet之间通信时出现空指针异常,java,servlets,Java,Servlets,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 ServletExc
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");
}
我的GetRosterServlet有重新修改名册列表的代码
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) {
}
});
}
受保护的void doPost(HttpServletRequest请求,
HttpServletResponse响应)引发ServletException,IOException{
花名册=connection.get花名册();
集合条目=花名册.getEntries();
对于(名册r:条目){
字符串user=r.getUser();
String name=r.getName();
System.out.println(名称+用户);
}
花名册.addRosterListener(新花名册Listener(){
//已忽略事件已添加公共无效项(集合
//地址){}
已删除公共无效条目(集合地址){
}
已更新公共无效条目(收集地址){
}
公共无效状态已更改(状态){
System.out.println(“状态更改:+Presence.getFrom()
+“+在场”;
}
@凌驾
已添加公共无效项(集合arg0){
}
});
}
现在问题是我的GetRosterServlet没有被通知我已登录到Gtalk..即LoginGtalkServlet未与GetRosterServlet通信,因此连接。GetRosterServlet()引发空指针异常
如何让花名册servlet知道用户已登录到gtalk,从而获得好友列表请注意,我对XMPP/gtalk并不熟悉 当您在
LoginGtalkServlet
中登录到它时,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放入重定向URL或POST正文中,然后GetRosterServlet
可以从request
提取会话ID,并通过该会话ID将其用于Gtalk
(注意:我刚才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。)您可以将连接对象保存在会话属性中
session .setAttribute("connection", connectionObj);
并且可以使用
session.getAttribute(“连接”)代码>异常堆栈跟踪非常重要,尤其是在NPE中。XMPPConnection可序列化吗。。(您不应该在会话中存储不可序列化的对象。