forumtag.java

这是学习Java必须读懂两套源代码

/**
 * Copyright (C) 2001 Yasna.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        Yasna.com (http://www.yasna.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Yazd" and "Yasna.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Yazd",
 *    nor may "Yazd" appear in their name, without prior written
 *    permission of Yasna.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL YASNA.COM OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Yasna.com. For more information
 * on Yasna.com, please see <http://www.yasna.com>.
 */

/**
 * Copyright (C) 2000 CoolServlets.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        CoolServlets.com (http://www.coolservlets.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Jive" and "CoolServlets.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Jive",
 *    nor may "Jive" appear in their name, without prior written
 *    permission of CoolServlets.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL COOLSERVLETS.COM OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of CoolServlets.com. For more information
 * on CoolServlets.com, please see <http://www.coolservlets.com>.
 */

package com.Yasna.forum.tags;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import javax.servlet.http.*;
import com.Yasna.forum.*;
import com.Yasna.forum.tags.*;

/**
 * JSP Tag <b>forum</b>, used to get information about current forum.
 * <p>
 * Requires that attribute <b>id</b> be set to the name of a
 * script variable for later use in JSP to retrieve Forum data
 * using &lt;jsp:getProperty/&gt;.
 * <p>
 * If optional attribute <b>trackVisits</b>="true", the date of the
 * users last visit to the forum will be saved when the user logs out
 * or their current session ends.
 * <p>
 * Optional attribute <b>match</b> can be set to the <b>id</b> of
 * a <b>match</b> tag to select only those forums that match the
 * forum extended properties specified by the <b>match</b> tag.
 * <p>
 * Gets the current forum from within a <b>forum_loop</b> tag or
 * the current forum from the user state information.
 * <p>
 * JSP Tag Lib Descriptor
 * <p><pre>
 *  &lt;name&gt;forum&lt;/name&gt;
 *  &lt;tagclass&gt;com.Yasna.forum.tags.ForumTag&lt;/tagclass&gt;
 *  &lt;teiclass&gt;com.Yasna.forum.tags.ForumTEI&lt;/teiclass&gt;
 *  &lt;bodycontent&gt;JSP&lt;/bodycontent&gt;
 *  &lt;info&gt;Get the current forum data&lt;/info&gt;
 *  &lt;attribute&gt;
 *    &lt;name&gt;id&lt;/name&gt;
 *    &lt;required&gt;true&lt;/required&gt;
 *    &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
 *  &lt;/attribute&gt;
 *  &lt;attribute&gt;
 *    &lt;name&gt;trackVisits&lt;/name&gt;
 *    &lt;required&gt;false&lt;/required&gt;
 *    &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
 *  &lt;/attribute&gt;
 *  &lt;attribute&gt;
 *    &lt;name&gt;match&lt;/name&gt;
 *    &lt;required&gt;false&lt;/required&gt;
 *    &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
 *  &lt;/attribute&gt;
 * </pre>
 *
 * @see ForumLoopTag
 * @see MatchTag
 * @see YazdProperty
 * @see GetYazdPropertyTag
 * @see SetYazdPropertyTag
 * @see YazdRequest
 *
 * @author Glenn Nielsen
 */

public class ForumTag extends TagSupport implements YazdProperty,
	ChangeForum, NewMessages
{
  private YazdState js = null;
  private YazdRequest jr = null;
  private Forum cf = null;
  // ID's of previous and next forum for use as a navigation aide
  private int prevForumID = -1;
  private int nextForumID = -1;
  // Flag whether date and time of last visit to this forum should be saved
  private boolean trackVisits = false;
  // Hash of forum extended properties to match on when selecting forums
  private Map match = new HashMap();

  /**
   * Method called at start of forum Tag to get Forum
   *
   * @return EVAL_BODY_INCLUDE if there is a forum or SKIP_BODY if there is not a forum to view
   */
  public final int doStartTag() throws JspException
  {
    // Get the user state information
    js = (YazdState)pageContext.getAttribute("yazdUserState",
                PageContext.SESSION_SCOPE);
    if( js == null ) {
      throw new JspException("Yazd forum tag could not get yazd state.");
    }

    // Get the user request information
    jr = (YazdRequest)pageContext.getAttribute("yazdUserRequest",
                PageContext.REQUEST_SCOPE);
    if( jr == null )
      throw new JspException("Yazd forum tag, could not find request");

   // See if we are nested inside a forum_loop tag
   ForumLoopTag fl = null;
    try {
      fl = (ForumLoopTag)this.findAncestorWithClass(this,
        Class.forName("com.Yasna.forum.tags.ForumLoopTag"));
    } catch(Exception e) {
    }

    if( fl != null ) {
      cf = fl.getForum();
      if( fl.getMatch() != null )
        match = fl.getMatch();
    } else {
      // Get the forum from user state information
      cf = jr.getForum();
    }

    if( cf == null || !cf.hasPermission(ForumPermissions.READ) )
      return SKIP_BODY;

    // Get the next and previous forum ID's just in case they are needed
    List forums = jr.getForums(match);
    int nextid;
    int previd = -1;
    int size = forums.size();
    for( int i = 0; i < size; i++ ) {
      nextid = ((Forum)forums.get(i)).getID();
      if( nextid == cf.getID() ) {
        prevForumID = previd;
	if( (i+1) < size )
	  nextForumID = ((Forum)forums.get(i+1)).getID();
	break;
      }
      previd = nextid;