extractpropertytag.java

OA典型例子

/*
 * $Id: ExtractPropertyTag.java,v 1.8 2001/10/24 04:15:27 gmurray Exp $
 * Copyright 2000 Sun Microsystems, Inc. All rights reserved.
 * Copyright 2000 Sun Microsystems, Inc. Tous droits r?erv?.
 */

package com.sure.taglibs.smart;

import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.BodyTagSupport;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Locale;

import java.lang.reflect.Method;
import com.sure.util.I18nUtil;

/**
 *
 * This class allows you to retrieve a parameter from the request and output it to the page
 * This should allow you to avoid expressions for extracting parameter info.
 *
 */

public class ExtractPropertyTag extends BodyTagSupport {

    private String sourceId = null;
    private String sourceScope = null;
    private String targetScope = null;
    private String property = null;
    private Object targetObject = null;
    private String destinationId = null;

    private ArrayList parameters = new ArrayList();

    public ExtractPropertyTag() {
	super();
    }

    public void setId(String sourceId){
	this.sourceId = sourceId;
    }

    public void setScope(String sourceScope){
	this.sourceScope = sourceScope.toLowerCase();
    }

    public void setDestinationId(String destinationId) {
	this.destinationId = destinationId;
    }

    public void setDestinationScope(String targetScope) {
	this.targetScope = targetScope.toLowerCase();
    }

    public void setProperty(String property) {
	this.property = property;
    }

    public int doStartTag() throws JspTagException {
	targetObject = null;
	if (sourceScope.equals("request")) {
	    targetObject = pageContext.getRequest().getAttribute(sourceId);
	} else if (sourceScope.equals("session")) {
	    targetObject = pageContext.getSession().getAttribute(sourceId);
	} else if (sourceScope.equals("page")) {
	    targetObject = pageContext.getAttribute(sourceId);
	}
	if (targetObject == null) {
	    throw new JspTagException("ExtractPropertyTag: Target Item " + sourceId + " not found in " + sourceScope + " scope.");
	}
	return EVAL_BODY_BUFFERED;
    }

    public int doEndTag() throws JspTagException {
	Object extractedObject = getProperty();
	if (targetScope.equals("request")) {
	    pageContext.getRequest().setAttribute(destinationId,extractedObject);
	} else if (targetScope.equals("session")) {
	    pageContext.getSession().setAttribute(destinationId, extractedObject);
	} else if (targetScope.equals("page")) {
	    pageContext.setAttribute(destinationId, extractedObject);
	}
	parameters = null;
	sourceId = null;
	sourceScope = null;
	targetScope = null;
	property = null;
	targetObject = null;
	destinationId = null;
	return EVAL_PAGE;
    }


    /**
     * Using the current Object use reflection to obtain the
     * String data from the element method the same as a JavaBean
     * would use:
     * <Br><br>e.g. a getXXXX method which has no parameters
     * <br>    The target method is the property attribute
     */
    private Object getProperty() throws JspTagException {
	//String targetMethod = property.substring(0,1).toUpperCase() + property.substring(1,property.length());
	String targetMethod = property;
	Object returnValue = null;
	try {
	    // set arguments if  needed
	    Class[] args = null;
	    Object[] params = null;
	    if (parameters == null) {
		Class[] tempArgs = {};
		args = tempArgs;
		Object[] tempParams = {};
		params = tempParams;
	    } else {
		// set the parameters here
		args = new Class[parameters.size()];
		params = new Object[parameters.size()];
		Iterator it = parameters.iterator();
		int index=0;
		while (it.hasNext()) {
		    ParameterItem item = (ParameterItem)it.next();
		    if (item.getType().equals("java.lang.String")) {
			args[index] = String.class;
			params[index] = item.getParameter();
		    } else if(item.getType().equals("int")) {
			args[index] = int.class;
			params[index] = new Integer(item.getParameter());
		    } else if(item.getType().equals("boolean")) {
			args[index] = boolean.class;
			params[index] = new Boolean(item.getParameter());
		    } else if(item.getType().equals("java.util.Locale")) {
			args[index] = Locale.class;
			Locale locale = I18nUtil.getLocaleFromString(item.getParameter());
			params[index] = locale;
		    }
		    index++;
		}
	    }

	    Method m = targetObject.getClass().getMethod(property, args);
	    if (m == null) {
		throw new JspTagException("ExtractPropertyTag: There is no method by the name of " + targetMethod);
	    }
	    returnValue = m.invoke(targetObject,params);
	} catch ( java.lang.NoSuchMethodException ex) {
	    throw new JspTagException("ExtractPropertyTag: Method for property " + property + " not found.");
	} catch (java.lang.reflect.InvocationTargetException ex) {
	    ex.printStackTrace();
	    throw new JspTagException("ExtractPropertyTag: Error calling method " + targetMethod + ":" + ex);
	} catch (java.lang.IllegalAccessException ex) {
	    throw new JspTagException("ExtractPropertyTag: Error calling method " + targetMethod + ":" + ex);
	}
	return returnValue;
    }

    public void addParameter(String parameter, String type) {
	parameters.add(new ParameterItem(parameter,type));
    }


    // This class represents a parameter for internal use in this class only

    class ParameterItem {

	private String parameter;
	private String type;

	ParameterItem(String parameter, String type) {
	    this.parameter = parameter;
	    this.type = type;
	}

	public String getParameter() {
	    return parameter;
	}

	public String getType() {
	    return type;
	}

    }
}