java.lang.IllegalStateException: Cannot call sendRedirect()

[Mauro Trevigno]

Hi guys,

I was reading several forums about this error, but still dont get it and i still cant fix the issue.

This is my web.xml
<servlet> <servlet-name>DBservlet</servlet-name> <servlet-class>com.company.pk.servlet.DBservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>DBservlet</servlet-name> <url-pattern>/DBservlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>login.jsp</welcome-file> </welcome-file-list>

So when i access for the first time, a login page will be open.. I log in properly,
This is my url when I run my project: http://localhost:8080/Company/
When i log in properly my url change to: localhost:8080/Company/DBservlet <-- this is my welcome.jsp

But if someone copy this url(localhost:8080/Company/DBservlet) recieve the following:
org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [DBservlet] in context with path [/Company] threw exception
java.lang.IllegalStateException: Cannot forward after response has been committed

If they put this url localhost:8080/Company/DBservlet need to redirect to login.jsp or this url http://localhost:8080/Company/, so they can log in properly.

This is my servlet code:

@WebServlet(name = "DBservlet", urlPatterns = {"/DBservlet"})
public class DBservlet extends HttpServlet {

   
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //response.setContentType("text/html;charset=UTF-8");
            response.sendRedirect("login.jsp");
             
  }
  
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
         processRequest(request, response);
         doPost(request, response);
    }


    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
       // processRequest(request, response);
        Connection con=null;
        PreparedStatement pst=null;
        ResultSet rs = null;
        //PrintWriter out=response.getWriter();
        
        
        
    try {
        
            System.out.println("test");
            boolean UserA = false;

Any opinion is welcome.


Thanks & Regards,
-M

[Mauro Trevigno]

Well, the only way that works was the following:

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

RequestDispatcher requestDispatcher;
requestDispatcher = request.getRequestDispatcher("/login.jsp");
requestDispatcher.forward(request, response);

}


@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
// doPost(request, response); // I removed the doPost.
}

Do you know if there is a better approach for this?

Thanks guys.

[Bear Bibeault]

You did not post all of the servlet code. Does it forward to a JSP?

[Mauro Trevigno]

Bear Bibeault wrote:You did not post all of the servlet code. Does it forward to a JSP?

Yes Bear,

  @Override  
    protected void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
       // processRequest(request, response);  
        Connection con=null;  
        PreparedStatement pst=null;  
        ResultSet rs = null;  
        //PrintWriter out=response.getWriter();  
          
          
          
    try {  
          
            System.out.println("test");  
            boolean UserA = false;  

 String UniqueName = request.getParameter("user");
            String LoginToken = request.getParameter("pass");
        
            con = DBconnect.getConnection();
          
            String query = "Select * from usuarios where UniqueName=? AND LoginToken=?";
           
            
            
            pst = con.prepareStatement(query);
            pst.setString(1, UniqueName);
            pst.setString(2, LoginToken);
            rs = pst.executeQuery();
             
            
            String names="";
            String email="";
            while(rs.next()){
                
                UserA = true;
               
                names = rs.getString("Name");
                email = rs.getString("EmailAddress");
            }
 
            if(UserA){
              
                request.setAttribute("Name", names);
                request.setAttribute("EmailAddress", email);
                
                request.getRequestDispatcher("/welcome.jsp").forward(request, response);
              //  HttpSession sesionOk = request.getSession();
                
            }else{
             
                request.getRequestDispatcher("/error.jsp").forward(request, response);
            }
 
     
        } catch (SQLException e) {
        e.getCause();
        }finally {
        try {
            if (null != rs)
            rs.close();
            } catch (SQLException e) {
            e.printStackTrace();
                }       
            try {
            if (null != pst)
            pst.close();
            } catch (SQLException e) {
            e.printStackTrace();
            }
            try {
            if (null != con)
            con.close();
            } catch (SQLException e) {
            e.printStackTrace();
              }//catch
            } //finally
        }//doPost

Thanks,
-M

[Bear Bibeault]

I see no sendRedirect() call in that servlet.

[Mauro Trevigno]

This is the complete Servlet file.

@WebServlet(name = "DBservlet", urlPatterns = {"/DBservlet"})  
public class DBservlet extends HttpServlet {  
  
     
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        //response.setContentType("text/html;charset=UTF-8");  
            response.sendRedirect("login.jsp");                  // HERE IS THE RESPONSE
               
  }  
    
    @Override  
    protected void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
         processRequest(request, response);  
         doPost(request, response);  
    }  

@Override    
    protected void doPost(HttpServletRequest request, HttpServletResponse response)    
            throws ServletException, IOException {    
       // processRequest(request, response);    
        Connection con=null;    
        PreparedStatement pst=null;    
        ResultSet rs = null;    
        //PrintWriter out=response.getWriter();    
            
            
            
    try {    
            
            System.out.println("test");    
            boolean UserA = false;    
  
 String UniqueName = request.getParameter("user");  
            String LoginToken = request.getParameter("pass");  
          
            con = DBconnect.getConnection();  
            
            String query = "Select * from usuarios where UniqueName=? AND LoginToken=?";  
             
              
              
            pst = con.prepareStatement(query);  
            pst.setString(1, UniqueName);  
            pst.setString(2, LoginToken);  
            rs = pst.executeQuery();  
               
              
            String names="";  
            String email="";  
            while(rs.next()){  
                  
                UserA = true;  
                 
                names = rs.getString("Name");  
                email = rs.getString("EmailAddress");  
            }  
   
            if(UserA){  
                
                request.setAttribute("Name", names);  
                request.setAttribute("EmailAddress", email);  
                  
                request.getRequestDispatcher("/welcome.jsp").forward(request, response);  
              //  HttpSession sesionOk = request.getSession();  
                  
            }else{  
               
                request.getRequestDispatcher("/error.jsp").forward(request, response);  
            }  
   
       
        } catch (SQLException e) {  
        e.getCause();  
        }finally {  
        try {  
            if (null != rs)  
            rs.close();  
            } catch (SQLException e) {  
            e.printStackTrace();  
                }         
            try {  
            if (null != pst)  
            pst.close();  
            } catch (SQLException e) {  
            e.printStackTrace();  
            }  
            try {  
            if (null != con)  
            con.close();  
            } catch (SQLException e) {  
            e.printStackTrace();  
              }//catch  
            } //finally  
        }//doPost  

So when i access for the fist time i go to the url localhost:8080/Company
When i log succesfull my url change to localhost:8080/DBservlet

But if someone try to copy and paste directly localhost:8080/DBservlet recieve the error.
Thats why i was adding the response.sendRedirect in the process Request.

Thanks,
-M