servlet getRequestDispatcher issue

[vic]

Hello All,

I am having this issue with my Servlet, cant seem to understand. I
have the snippet of the servlet below whihch forwards the request to a
jsp based on what the method condition returns. The servlet however
does forward to the appropriate jsp but then gives a NUll pointer
exception.

Here is the servlet snippet

public void doPost (HttpServletRequest request, HttpServletResponse
response) throws ServletException, java.io.IOException {


ausername = request.getParameter("ausername");
apassword = request.getParameter("apassword");

try {

authenticate(ausername, apassword); //returns true if user is
valid and else false

if(aReturn == true) {
this.getServletContext().getRequestDispatcher("/gototrue.jsp").forward(request,
response);

}
else {
this.getServletContext().getRequestDispatcher("/gotofalse.jsp").forward(request,
response);
}
}
catch (ServletException se) {
}

Here is the error log i get:

<Error> <HTTP> <[WebAppServletContext(1531469,myapp,/
myapp)] Servlet failed with Exception
java.lang.NullPointerException
at csf.webcntrl.HTTPRMIAdapter.doPost(HTTPRMIAdapter.java:71)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:262)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:198)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe
rvletContext.java:2637)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestIm
pl.java:2359)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)

Am i missing something, session , ServletContext() or something on
those lines.

Any help is appreciated

 

[Tony Morris]

Hello All,

I am having this issue with my Servlet, cant seem to understand. I
have the snippet of the servlet below whihch forwards the request to a
jsp based on what the method condition returns. The servlet however
does forward to the appropriate jsp but then gives a NUll pointer
exception.

Here is the servlet snippet

public void doPost (HttpServletRequest request, HttpServletResponse
response) throws ServletException, java.io.IOException {


ausername = request.getParameter("ausername");
apassword = request.getParameter("apassword");

try {

authenticate(ausername, apassword); //returns true if user is
valid and else false

if(aReturn == true) {
this.getServletContext().getRequestDispatcher("/gototrue.jsp").forward(reque
st,
response);

}
else {
this.getServletContext().getRequestDispatcher("/gotofalse.jsp").forward(requ
est,
response);
}
}
catch (ServletException se) {
}

Here is the error log i get:

<Error> <HTTP> <[WebAppServletContext(1531469,myapp,/
myapp)] Servlet failed with Exception
java.lang.NullPointerException
at csf.webcntrl.HTTPRMIAdapter.doPost(HTTPRMIAdapter.java:71)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm

pl.java:262)
at

weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm

pl.java:198)
at

weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe

rvletContext.java:2637)
at

weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestIm
pl.java:2359)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)

Am i missing something, session , ServletContext() or something on
those lines.

Any help is appreciated

Before I speculate at what the problem is:

a) if(x == true) // yuk ! Better written as if(x)
b) Why are you writing your own security mechanism ? Are you encouraging
attacks against your application ? Why aren't you using J2EE authentication
mechanisms ?

Problem (speculation):
I'll bet my leftie that
this.getServletContext().getRequestDispatcher("/gototrue.jsp") is returning
null.

You can test this by:
RequestDispatcher rd =
this.getServletContext().getRequestDispatcher("/gototrue.jsp");

if(rd == null)
{
throw new ServletException("I broke it");
}
else
{
rd.forward(request, response);
}

Good luck !

--
Tony Morris
(BInfTech, Cert 3 I.T.)
Software Engineer
(2003 VTR1000F)
Sun Certified Programmer for the Java 2 Platform (1.4)
Sun Certified Developer for the Java 2 Platform

 

[psrikant]

Here is what i feel is giving u the error.

when u r comparing aReturn == true, aReturn should have some value that
has been returned by the authenticate method. You must do

aReturn = authenticate(ausername, apassword);

This should solve your NullPointerException.

hope it helps.

Let me know

Hello All,

I am having this issue with my Servlet, cant seem to understand. I
have the snippet of the servlet below whihch forwards the request to a
jsp based on what the method condition returns. The servlet however
does forward to the appropriate jsp but then gives a NUll pointer
exception.

Here is the servlet snippet

public void doPost (HttpServletRequest request, HttpServletResponse
response) throws ServletException, java.io.IOException {


ausername = request.getParameter("ausername");
apassword = request.getParameter("apassword");

try {

authenticate(ausername, apassword); //returns true if user is
valid and else false

if(aReturn == true) {
this.getServletContext().getRequestDispatcher("/gototrue.jsp").forward(request,
response);

}
else {
this.getServletContext().getRequestDispatcher("/gotofalse.jsp").forward(request,
response);
}
}
catch (ServletException se) {
}

Here is the error log i get:

<Error> <HTTP> <[WebAppServletContext(1531469,myapp,/
myapp)] Servlet failed with Exception
java.lang.NullPointerException
at csf.webcntrl.HTTPRMIAdapter.doPost(HTTPRMIAdapter.java:71)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)

at

javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at

weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm

pl.java:262)
at

weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm

pl.java:198)
at

weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe

rvletContext.java:2637)
at

weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestIm

pl.java:2359)
at

weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)

Am i missing something, session , ServletContext() or something on
those lines.

Any help is appreciated