messagetag.java

一个实用工具类

/*
 * Copyright (C) butor.com. All rights reserved.
 *
 * This software is published under the terms of the GNU Library General
 * Public License (GNU LGPL), a copy of which has been included with this
 * distribution in the LICENSE.txt file. 
 */


package org.butor.web.taglib.bean;

import java.util.Locale;

import javax.servlet.ServletRequest;
import javax.servlet.jsp.JspException;

import org.apache.struts.util.RequestUtils;
import org.apache.struts.util.ResponseUtils;
import org.butor.messageResources.MessageResourcesService;
import org.butor.web.helper.StandardAttributes;

/**
 * @author sawanai
 *
 * This ressource message tag is derived from struts MessageTag.
 * The difference is that try to find the locale in the request before
 * the page and session context.
 */
public class MessageTag extends org.apache.struts.taglib.bean.MessageTag {

	/**
	 * Constructor for MessageTag.
	 */
	public MessageTag() {
		super();
	}

	/**
	 * The first optional argument message resource key.
	 */
	protected String arg0Key = null;

	public String getArg0Key() {
		return (this.arg0Key);
	}

	public void setArg0Key(String arg0Key) {
		this.arg0Key = arg0Key;
	}


	/**
	 * The second optional argument message resource key.
	 */
	protected String arg1Key = null;

	public String getArg1Key() {
		return (this.arg1Key);
	}

	public void setArg1Key(String arg1Key) {
		this.arg1Key = arg1Key;
	}


	/**
	 * The third optional argument message resource key.
	 */
	protected String arg2Key = null;

	public String getArg2Key() {
		return (this.arg2Key);
	}

	public void setArg2Key(String arg2Key) {
		this.arg2Key = arg2Key;
	}


	/**
	 * The fourth optional argument message resource key.
	 */
	protected String arg3Key = null;

	public String getArg3Key() {
		return (this.arg3Key);
	}

	public void setArg3Key(String arg3Key) {
		this.arg3Key = arg3Key;
	}


	/**
	 * The fifth optional argument message resource key.
	 */
	protected String arg4Key = null;

	public String getArg4Key() {
		return (this.arg4Key);
	}

	public void setArg4Key(String arg4Key) {
		this.arg4Key = arg4Key;
	}


	/**
	 * Process the start tag.
	 *
	 * @exception JspException if a JSP exception has occurred
	 */
	public int doStartTag() throws JspException {

		String key = this.key;
		if (key == null) {
			// Look up the requested property value
			Object value = RequestUtils.lookup(pageContext, name, property, scope);
			if (value != null && !(value instanceof String)) {
				JspException e = new JspException("MessageTag: key found by preoprty is not a string!");
				RequestUtils.saveException(pageContext, e);
				throw e;
			}
			key = (String) value;
		}
		
		if (key == null) {
			JspException e = new JspException("MessageTag: key not found!");
			RequestUtils.saveException(pageContext, e);
			throw e;
		}

		ServletRequest sr = pageContext.getRequest();

		// Retrieve the message string we are looking for
		if (this.localeKey == null) {
			this.localeKey = StandardAttributes.LOCALE_KEY;
		}

		Locale locale = (Locale) sr.getAttribute(this.localeKey);
		if (locale == null) {
			locale = RequestUtils.retrieveUserLocale(pageContext, this.localeKey);
		}

		// Construct the optional arguments array we will be using
		Object args[] = new Object[5];
		args[0] = arg0Key != null ? MessageResourcesService.getMessage(locale, arg0Key) : arg0;
		args[1] = arg1Key != null ? MessageResourcesService.getMessage(locale, arg1Key) : arg1;
		args[2] = arg2Key != null ? MessageResourcesService.getMessage(locale, arg2Key) : arg2;
		args[3] = arg3Key != null ? MessageResourcesService.getMessage(locale, arg3Key) : arg3;
		args[4] = arg4Key != null ? MessageResourcesService.getMessage(locale, arg4Key) : arg4;

		String message = MessageResourcesService.getMessage(locale, key, args);
		if (message != null) {
			// Print the retrieved message to our output writer
			ResponseUtils.write(pageContext, message);
		}
		
		// Continue processing this page
		return (SKIP_BODY);

	}
}