updateservlet.java

Java程序设计高级教程（第三版）

package com.nearhills.servlets;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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.NoSessionException;

/**
 * @version 	1.0
 * @author
 */
public class UpdateServlet extends HttpServlet {

	/**
	* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	*/
	public void doGet(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
      try {
         HttpSession session = req.getSession(false);
         if ( session == null ) {
            throw new NoSessionException(
              "No session: " +
              "have you registered or Logged in?" );
         }
         RequestDispatcher rd = getServletContext().
            getRequestDispatcher("/update.jsp");
         rd.forward( req, resp );
      } catch ( Exception e ) {
      	 req.setAttribute( "exception", e );
         RequestDispatcher rd = getServletContext().
         getRequestDispatcher( 
            "/errorReport.jsp" );
         rd.forward( req, resp );
      }
	}

	/**
	* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	*/
	public void doPost(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
      try { 
         if ( ! req.isRequestedSessionIdValid() ) {
            throw new NoSessionException(
               "This http request has no valid session." );
         }
         HttpSession session = req.getSession();
         ClubMember skier = checkNewData( req, session );
         skier.update();
         session.setAttribute( "member", skier );
         confirmUpdate( req, resp );
      } catch( BadDataException e )  {
      	 req.setAttribute( "message", e.getMessage() );
         RequestDispatcher rd = getServletContext().
         getRequestDispatcher( 
            "/badinputMessage.jsp" );
         rd.forward( req, resp );
      } catch( Exception e ) {
      	 req.setAttribute( "exception", e );
         RequestDispatcher rd = getServletContext().
         getRequestDispatcher( 
            "/errorReport.jsp" );
         rd.forward( req, resp );
      } 
      return;

	}
  private ClubMember checkNewData( 
      HttpServletRequest req, HttpSession session )
      throws BadDataException 
   {
      boolean change = false;
      ClubMember skier = (ClubMember) session.
         getAttribute( "member" );
      if ( ! skier.getFirstName().equals( 
            req.getParameter( "FNAME" ) ) ) {
         skier.setFirstName( 
            req.getParameter( "FNAME" ) );
         change = true;
      }
      if ( ! skier.getMiddleName().equals( 
            req.getParameter( "MNAME" ) ) ) {
         skier.setMiddleName( 
            req.getParameter( "MNAME" ) );
         change = true;
      }
      if ( ! skier.getLastName().equals( 
            req.getParameter( "LNAME" ) ) ) {
         skier.setLastName( 
            req.getParameter( "LNAME" ) );
         change = true;
      }
      if ( ! skier.getPhoneNumber().equals( 
            req.getParameter( "PHONE" ) ) ) {
         skier.setPhoneNumber( 
            req.getParameter( "PHONE" ) ); 
         change = true;
      }
      if ( ! skier.getAbility().equals( 
            req.getParameter( "ABILITY" ) ) ) {
         skier.setAbility( 
            req.getParameter( "ABILITY" ) ); 
         change = true;
      }
      if ( ! change ) {
         throw new BadDataException(
            "No changes requested." );
      }
      return skier;
   }

   public void confirmUpdate( HttpServletRequest req,
      HttpServletResponse res )
      throws IOException, ServletException
   {  
      try {
         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 );
      }        
   }
}