loginaction.java

一个关于STRUTS的学习资料

package com.oreilly.actions;

import java.io.IOException;
import java.rmi.RemoteException;
import javax.ejb.CreateException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionForward;
import com.oreilly.forms.LoginForm;



/**
 * <strong>LoginAction</strong> demonstrates how an action class is called within the struts framework
 * For the purposes of this sample, we simple demonstrate how the perform is called,
 * a sample action, and a return
 * 
 *@author Sue Spielman Switchback Software LLC www.switchbacksoftware.com
 */
public class LoginAction extends AbstStrutsActionBase 
{
    /**
     * Black box method used to authenticate a user. There would typically
     * be a bean (or EJB) here that actually does the work.
     * A lookup would be done (as shown in the base class) and create on the home interface
     * to authenticate the user against some backend database.
     *@param String containing username
     *@param String containing password
     *@return boolean - true authenticated, false not authenticated.
     */
    public boolean authenticate(String username, String password) 
    {
        // Do the appropriate lookup and calls. 
        // That code is not provided as part of this sample.
        // Instead, it is just to demonstrate the interaction
        // of the action class with business logic tier.
        return(true);
    }

    /**
     * Override base class with specific <strong>perform</strong> implementation
     * for this class.
     * @param mapping The ActionMapping used to select this instance
     * @param actionForm The optional AbstActionFormBase bean for this request (if any)
     * @param request The HTTP request we are processing
     * @param response The HTTP response we are creating
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet exception occurs
     */
    public ActionForward perform(ActionMapping mapping, ActionForm form,
        HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException 
    {
        // Assume that the login fails, so that the login page is redisplayed
        // if the user isn't authenticated
        boolean validLogin=false;
        ActionForward actionForward = mapping.findForward(LOGIN);
        // Create the container for any errors that occur
        ActionErrors errors = new ActionErrors();
        
        // Extract attributes and parameters we will need from the incoming
        // form.
        LoginForm loginForm = (LoginForm) form;
        String userName = null;
        String password = null;
        if (loginForm != null){
            userName = loginForm.getUserName();
            password = loginForm.getPassword();
            validLogin = authenticate(userName, password);
        }
        if (validLogin){
            // Forward control to the specified 'success' URI specified in the structs-config.xml
            actionForward = mapping.findForward(SUCCESS);
            // Save something into the session for later use.
            request.getSession(true).setAttribute("USERNAME", userName);
            
            
        } else  {
            errors.add("login", new ActionError("error.login.authenticate"));
        }
        // If any messages is required, save the specified error messages keys
        // into the HTTP request for use by the <struts:errors> tag.
        if (!errors.empty()) {
            saveErrors(request, errors);
        }

        // Forward control to the appropriate URI as determined by the action.
        return (actionForward);
    }
        

}