errorstag.java

structs源码

/*
 * $Id: ErrorsTag.java 471754 2006-11-06 14:55:09Z husted $
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.struts.taglib.html;

import org.apache.struts.Globals;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.action.ActionMessages;
import org.apache.struts.taglib.TagUtils;
import org.apache.struts.util.MessageResources;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

import java.util.Iterator;

/**
 * Custom tag that renders error messages if an appropriate request attribute
 * has been created.  The tag looks for a request attribute with a reserved
 * key, and assumes that it is either a String, a String array, containing
 * message keys to be looked up in the module's MessageResources, or an object
 * of type <code>org.apache.struts.action.ActionErrors</code>. <p> The
 * following optional message keys will be utilized if corresponding messages
 * exist for them in the application resources:
 *
 * <ul>
 *
 * <li><b>errors.header</b> - If present, the corresponding message will be
 * rendered prior to the individual list of error messages.</li>
 *
 * <li><b>errors.footer</b> - If present, the corresponding message will be
 * rendered following the individual list of error messages.</li>
 *
 * <li><b>errors.prefix</b> - If present, the corresponding message will be
 * rendered before each individual error message.</li>
 *
 * <li><b>errors.suffix</b> - If present, the corresponding message will be
 * rendered after each individual error message.</li>
 *
 * </ul>
 *
 * @version $Rev: 471754 $ $Date: 2005-08-21 19:08:45 -0400 (Sun, 21 Aug 2005)
 *          $
 */
public class ErrorsTag extends TagSupport {
    /**
     * The message resources for this package.
     */
    protected static MessageResources messages =
        MessageResources.getMessageResources(Constants.Package
            + ".LocalStrings");

    // ----------------------------------------------------------- Properties

    /**
     * The servlet context attribute key for our resources.
     */
    protected String bundle = null;

    /**
     * The session attribute key for our locale.
     */
    protected String locale = Globals.LOCALE_KEY;

    /**
     * The request attribute key for our error messages (if any).
     */
    protected String name = Globals.ERROR_KEY;

    /**
     * The name of the property for which error messages should be returned,
     * or <code>null</code> to return all errors.
     */
    protected String property = null;

    /**
     * The message resource key for errors header.
     */
    protected String header = null;

    /**
     * The message resource key for errors footer.
     */
    protected String footer = null;

    /**
     * The message resource key for errors prefix.
     */
    protected String prefix = null;

    /**
     * The message resource key for errors suffix.
     */
    protected String suffix = null;

    public String getBundle() {
        return (this.bundle);
    }

    public void setBundle(String bundle) {
        this.bundle = bundle;
    }

    public String getLocale() {
        return (this.locale);
    }

    public void setLocale(String locale) {
        this.locale = locale;
    }

    public String getName() {
        return (this.name);
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getProperty() {
        return (this.property);
    }

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

    public String getHeader() {
        return (header == null) ? "errors.header" : header;
    }

    public void setHeader(String header) {
        this.header = header;
    }

    public String getFooter() {
        return (footer == null) ? "errors.footer" : footer;
    }

    public void setFooter(String footer) {
        this.footer = footer;
    }

    public String getPrefix() {
        return (prefix == null) ? "errors.prefix" : prefix;
    }

    public void setPrefix(String prefix) {
        this.prefix = prefix;
    }

    public String getSuffix() {
        return (suffix == null) ? "errors.suffix" : suffix;
    }

    public void setSuffix(String suffix) {
        this.suffix = suffix;
    }

    // ------------------------------------------------------- Public Methods

    /**
     * Render the specified error messages if there are any.
     *
     * @throws JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {
        // Were any error messages specified?
        ActionMessages errors = null;

        try {
            errors =
                TagUtils.getInstance().getActionMessages(pageContext, name);
        } catch (JspException e) {
            TagUtils.getInstance().saveException(pageContext, e);
            throw e;
        }

        if ((errors == null) || errors.isEmpty()) {
            return (EVAL_BODY_INCLUDE);
        }

        boolean headerPresent =
            TagUtils.getInstance().present(pageContext, bundle, locale,
                getHeader());

        boolean footerPresent =
            TagUtils.getInstance().present(pageContext, bundle, locale,
                getFooter());

        boolean prefixPresent =
            TagUtils.getInstance().present(pageContext, bundle, locale,
                getPrefix());

        boolean suffixPresent =
            TagUtils.getInstance().present(pageContext, bundle, locale,
                getSuffix());

        // Render the error messages appropriately
        StringBuffer results = new StringBuffer();
        boolean headerDone = false;
        String message = null;
        Iterator reports =
            (property == null) ? errors.get() : errors.get(property);

        while (reports.hasNext()) {
            ActionMessage report = (ActionMessage) reports.next();

            if (!headerDone) {
                if (headerPresent) {
                    message =
                        TagUtils.getInstance().message(pageContext, bundle,
                            locale, getHeader());

                    results.append(message);
                }

                headerDone = true;
            }

            if (prefixPresent) {
                message =
                    TagUtils.getInstance().message(pageContext, bundle, locale,
                        getPrefix());
                results.append(message);
            }

            if (report.isResource()) {
                message =
                    TagUtils.getInstance().message(pageContext, bundle, locale,
                        report.getKey(), report.getValues());
            } else {
                message = report.getKey();
            }

            if (message != null) {
                results.append(message);
            }

            if (suffixPresent) {
                message =
                    TagUtils.getInstance().message(pageContext, bundle, locale,
                        getSuffix());
                results.append(message);
            }
        }

        if (headerDone && footerPresent) {
            message =
                TagUtils.getInstance().message(pageContext, bundle, locale,
                    getFooter());
            results.append(message);
        }

        TagUtils.getInstance().write(pageContext, results.toString());

        return (EVAL_BODY_INCLUDE);
    }

    /**
     * Release any acquired resources.
     */
    public void release() {
        super.release();
        bundle = Globals.MESSAGES_KEY;
        locale = Globals.LOCALE_KEY;
        name = Globals.ERROR_KEY;
        property = null;
        header = null;
        footer = null;
        prefix = null;
        suffix = null;
    }
}