cvs commit: jakarta-taglibs/jdbc/src/org/apache/taglibs/jdbc/statement WasEmptyTag.java

[mo...@apache.org]

morgand     01/03/06 13:20:29

  Added:       jdbc/src/org/apache/taglibs/jdbc/statement WasEmptyTag.java
  Log:
  wasEmpty tag for empty result sets
  
  Revision  Changes    Path
  1.1                  jakarta-taglibs/jdbc/src/org/apache/taglibs/jdbc/statement/WasEmptyTag.java
  
  Index: WasEmptyTag.java
  ===================================================================
  
  /*
   *
   * ====================================================================
   *
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 1999 The Apache Software Foundation.  All rights
   * reserved.
   *
   * 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 acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Group.
   *
   * 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 THE APACHE SOFTWARE FOUNDATION 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 the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.taglibs.jdbc.statement;
  
  import javax.servlet.jsp.JspTagException;
  import javax.servlet.jsp.tagext.TagSupport;
  
  /**
   * <p>Executes its body if the last ResultSet tag received 0 rows
   * from the database.  You must be after a ResultSet tag and inside
   * a StatementTag or PreparedStatementTag, or an error will be generated.</p>
   *
   * <p>The subclass WasNotEmpty sets the "value" property to false,
   * and therefore executes its tag body is the ResultSet contained
   * <i>greater than</i> 0 rows.  
   * 
   * <p>JSP Tag Lib Descriptor
   * <pre>
   * &lt;name>wasEmpty&lt;/name>
   * &lt;tagclass>org.apache.taglibs.jdbc.statement.WasEmptyTag&lt;/tagclass>
   * &lt;bodycontent>JSP&lt;/bodycontent>
   * &lt;info>
   * Executes its body if the last ResultSet tag received 0 rows
   * from the database.  You must be after a ResultSet tag and inside
   * a StatementTag or PreparedStatementTag, or an error will be generated.
   * &lt;/info>
   * </pre>
   * 
   * @author Morgan Delagrange
   * @see ResultSet
   * @see wasNotEmptyTag
   */
  public class WasEmptyTag extends TagSupport {
  
    private boolean _value = true;
  
    /**
     * Sets the necessary boolean value in order to
     * execute the tag body.
     * 
     * @param value
     */
    public void setValue(boolean value) {
      _value = value;
    }
  
    /**
     * Get the enclosing StatementTag tag
     * 
     * @return StatementTag
     * @exception ClassNotFoundException
     */
    private StatementTag getStatementTag() throws ClassNotFoundException {
      StatementTag statementTag = 
      (StatementTag) findAncestorWithClass(this, Class.forName("org.apache.taglibs.jdbc.statement.StatementTag"));
      return statementTag;
    }
  
    public int doStartTag() throws JspTagException {
      try {
        StatementTag stmtTag = getStatementTag();
        int rowCount = stmtTag.getTotalRowCount();
  
        if (rowCount == -1) {
          throw new JspTagException("WasEmpty and WasNotEmpty tags must follow a ResultSet tag.");
        }
  
        boolean wasEmpty = true;
        if (rowCount > 0) {
          wasEmpty = false;
        }
  
        // evaluate the body only if wasEmpty matches the desired
        // value (true or false)
        if (wasEmpty == _value) {
          return EVAL_BODY_INCLUDE;
        } else {
          return SKIP_BODY;
        }
      } catch (ClassNotFoundException e) {
        throw new JspTagException(e.toString());
      }
    }
  
    public void release() {
      _value = true;
    }
  }