actionhandler.java

java 写的一个新闻发布系统

package org.jahia.utils;

import java.lang.reflect.*;
import java.util.*;
import java.io.*;
import javax.servlet.http.*;


/**
 * Class ActionHandler: determines the method to invoke for an Application
 * (typically a Web Application), given an action.
 *
 * @author  Stephane Boury, Jerome Tamiotti
 * @version 1.1
 */
public class ActionHandler {
    
    /* The class on which to call the methods */
    private Class actionClass; 
    
    /** 
	 * An instance of the class on which to call the methods
	 * This instance is null here because the class is static,
	 * and the parameter of 'invokeMethod' method will be ignored
	 */
    private Object instanceOfClass = null;
    

    /* The hashtable containing the method names */
	private Properties methods;
    
    /**
	 * Class constructor: builds the hashtable by reading a flat file.
	 *
	 * @param propsFile     the full path to the file containing pairs of
	 * "action - method name"
	 * @param theClass      the name of the Class on which to call the methods
	 */
    public ActionHandler(String propsFile, String theClass) {

        methods = new Properties();
		try {
			FileInputStream fis = new FileInputStream(propsFile);
			methods.load(fis);
			fis.close();
		}
		catch (IOException e) {
			JahiaConsole.println("ActionHandler-ActionHandler", e.toString());
		}
        
        try {
            actionClass = Class.forName(theClass);
        } catch (ClassNotFoundException ex) {
            JahiaConsole.println("ActionHandler-ActionHandler", ex.toString());
        } catch (Exception ex) {
            JahiaConsole.println("ActionHandler-ActionHandler", ex.toString());
        }
    }
    
    /**
     * Calls the appropriate method given the action.
     *
     * @param action    the action that triggers the method to call
     * @param request   the request parameter for the method
     */        
    public Object call(String action, HttpServletRequest request) throws NullPointerException {
        
        String theMethod = methods.getProperty(action);
		if (theMethod == null) { //method not found in list
			JahiaConsole.println("ActionHandler-call","No method found for action " + action);
			throw new NullPointerException();
		}
        try {
			Class theParams[] = {Class.forName("javax.servlet.http.HttpServletRequest")};
            Method thisMethod = actionClass.getDeclaredMethod(theMethod, theParams);
			Object args[] = {request};
            return thisMethod.invoke(instanceOfClass, args);

        } catch(ClassNotFoundException cnfe) {
            JahiaConsole.println("ActionHandler-call", cnfe.toString());
			throw new NullPointerException();

		} catch(NoSuchMethodException nsme) {
            JahiaConsole.println("ActionHandler-call", nsme.toString());
			throw new NullPointerException();

		} catch(IllegalAccessException iae) {
            JahiaConsole.println("ActionHandler-call", iae.toString());
			throw new NullPointerException();

		} catch(InvocationTargetException ite) {
            JahiaConsole.println("ActionHandler-call", ite.toString());
			throw new NullPointerException();
		} 
    }

        
    /**
     * Calls the appropriate method given the action.
     *
     * @param action     the action that triggers the method to call
     * @param request    the request parameter for the method
     * @param response   the response parameter for the method
     */        
    public Object call( Object instanceOfClass, String action, HttpServletRequest request, HttpServletResponse response) throws NullPointerException {
        
        String theMethod = methods.getProperty(action);
		if (theMethod == null) { //method not found in list
			JahiaConsole.println("ActionHandler-call","No method found for action " + action);
			throw new NullPointerException();
		}
        try {
			Class theParams[] = {Class.forName("javax.servlet.http.HttpServletRequest"),Class.forName("javax.servlet.http.HttpServletResponse")};
            Method thisMethod = actionClass.getDeclaredMethod(theMethod, theParams);
			Object args[] = {request,response};

            return thisMethod.invoke(instanceOfClass, args);

        } catch(ClassNotFoundException cnfe) {
            JahiaConsole.printe("ActionHandler-call", cnfe);
			throw new NullPointerException();

		} catch(NoSuchMethodException nsme) {
            JahiaConsole.printe("ActionHandler-call", nsme);
			throw new NullPointerException();

		} catch(IllegalAccessException iae) {
            JahiaConsole.printe("ActionHandler-call", iae);
			throw new NullPointerException();

		} catch(InvocationTargetException ite) {
            JahiaConsole.printe("ActionHandler-call", ite);
			throw new NullPointerException();
		} 
    }
        
}