matchtag.java

structs源码

/*
 * $Id: MatchTag.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.logic;

import org.apache.struts.taglib.TagUtils;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;

/**
 * Evalute the nested body content of this tag if the specified value is a
 * substring of the specified variable.
 *
 * @version $Rev: 471754 $ $Date: 2004-10-16 12:38:42 -0400 (Sat, 16 Oct 2004)
 *          $
 */
public class MatchTag extends ConditionalTagBase {
    // ------------------------------------------------------------- Properties

    /**
     * The location where the match must exist (<code>start</code> or
     * <code>end</code>), or <code>null</code> for anywhere.
     */
    protected String location = null;

    /**
     * The value to which the variable specified by other attributes of this
     * tag will be matched.
     */
    protected String value = null;

    public String getLocation() {
        return (this.location);
    }

    public void setLocation(String location) {
        this.location = location;
    }

    public String getValue() {
        return (this.value);
    }

    public void setValue(String value) {
        this.value = value;
    }

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

    /**
     * Release all allocated resources.
     */
    public void release() {
        super.release();
        location = null;
        value = null;
    }

    // ------------------------------------------------------ Protected Methods

    /**
     * Evaluate the condition that is being tested by this particular tag, and
     * return <code>true</code> if the nested body content of this tag should
     * be evaluated, or <code>false</code> if it should be skipped. This
     * method must be implemented by concrete subclasses.
     *
     * @throws JspException if a JSP exception occurs
     */
    protected boolean condition()
        throws JspException {
        return (condition(true));
    }

    /**
     * Evaluate the condition that is being tested by this particular tag, and
     * return <code>true</code> if the nested body content of this tag should
     * be evaluated, or <code>false</code> if it should be skipped. This
     * method must be implemented by concrete subclasses.
     *
     * @param desired Desired value for a true result
     * @throws JspException if a JSP exception occurs
     */
    protected boolean condition(boolean desired)
        throws JspException {
        // Acquire the specified variable
        String variable = null;

        if (cookie != null) {
            Cookie[] cookies =
                ((HttpServletRequest) pageContext.getRequest()).getCookies();

            if (cookies == null) {
                cookies = new Cookie[0];
            }

            for (int i = 0; i < cookies.length; i++) {
                if (cookie.equals(cookies[i].getName())) {
                    variable = cookies[i].getValue();

                    break;
                }
            }
        } else if (header != null) {
            variable =
                ((HttpServletRequest) pageContext.getRequest()).getHeader(header);
        } else if (name != null) {
            Object value =
                TagUtils.getInstance().lookup(pageContext, name, property, scope);

            if (value != null) {
                variable = value.toString();
            }
        } else if (parameter != null) {
            variable = pageContext.getRequest().getParameter(parameter);
        } else {
            JspException e =
                new JspException(messages.getMessage("logic.selector"));

            TagUtils.getInstance().saveException(pageContext, e);
            throw e;
        }

        if (variable == null) {
            JspException e =
                new JspException(messages.getMessage("logic.variable", value));

            TagUtils.getInstance().saveException(pageContext, e);
            throw e;
        }

        // Perform the comparison requested by the location attribute
        boolean matched = false;

        if (location == null) {
            matched = (variable.indexOf(value) >= 0);
        } else if (location.equals("start")) {
            matched = variable.startsWith(value);
        } else if (location.equals("end")) {
            matched = variable.endsWith(value);
        } else {
            JspException e =
                new JspException(messages.getMessage("logic.location", location));

            TagUtils.getInstance().saveException(pageContext, e);
            throw e;
        }

        // Return the final result
        return (matched == desired);
    }
}