loginservlet.java

Java程序设计高级教程（第三版）

package com.nearhills.servlets;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.nearhills.BadDataException;
import com.nearhills.ClubMember;
import com.nearhills.DBopException;
import com.nearhills.SkiClubDB;

/**
 * @version 	1.0
 * @author
 */
public class LoginServlet extends HttpServlet {
	
	/**
	* @see javax.servlet.GenericServlet#void ()
	*/
	public void init() throws ServletException {
		super.init();
	}

	/**
	* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	*/
	public void doPost(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {

      HttpSession session = req.getSession(false);
      if ( session != null ) {
         session.invalidate();
      }
      ClubMember skier = null;
      try {
         skier = getMemberData(req);
         confirmLogin( req, resp, skier );
      } catch( BadDataException e ) { 
      	 req.setAttribute( "message", e.getMessage() );
         RequestDispatcher rd = getServletContext().
         getRequestDispatcher( 
            "/badinputMessage.jsp" );
         rd.forward( req, resp );
      } catch( Exception e ) {
      	getServletContext().
      	setAttribute( "exception", e );
         RequestDispatcher rd = getServletContext().
         getRequestDispatcher( 
            "/errorReport.jsp" );
         rd.forward( req, resp );
      }
      return;
	}

   private ClubMember 
      getMemberData( HttpServletRequest req )
      throws DBopException, SQLException, 
             BadDataException {
      int id;
      String lastName = req.getParameter( "LNAME" );
      if ( lastName.length() == 0 ) {
         throw new BadDataException( 
            "Last Name Required" );
      } 
      String sid = req.getParameter( "ID" );
      try {
         id = Integer.parseInt( sid );
      } catch( NumberFormatException e ) {
         throw new BadDataException( 
            "ID must be an integer" );
      } 
      ClubMember skier = SkiClubDB.getMemberByID( id );
      if ( skier == null ) {
         throw new BadDataException(
            "The ID " + id + " is not correct." );
      }
      if ( ! ( skier.getLastName().equals( lastName ) ) )
      {
          throw new BadDataException( 
             "Last name does not match records." );
      } 	
      return skier;
}
 
   public void confirmLogin( HttpServletRequest req,
      HttpServletResponse res, ClubMember skier )
      throws IOException, ServletException
   {   
      try { 
         HttpSession session = req.getSession( true );
         session.setAttribute( "member", skier );
         RequestDispatcher rd = getServletContext().
            getRequestDispatcher(
            "/memberHome.jsp");
         rd.forward( req, res );
      } catch ( Exception e ) { 
      	 req.setAttribute( "exception", e );
         RequestDispatcher rd = getServletContext().
         getRequestDispatcher( 
            "/errorReport.jsp" );
         rd.forward( req, res );
      }      
   }
}