Source code: com/RuntimeCollective/webapps/tag/FindBeanCollectionTag.java

   /* $Header: /home/CVS/rjp/src/com/RuntimeCollective/webapps/tag/FindBeanCollectionTag.java,v 1.3 2003/09/30 15:13:18 joe Exp $
    * $Revision: 1.3 $
    * $Date: 2003/09/30 15:13:18 $
    *
    * ====================================================================
    *
    * Josephine : http://www.runtime-collective.com/josephine/index.html
    *
    * Copyright (C) 2003 Runtime Collective
   * 
   * This product includes software developed by the
   * Apache Software Foundation (http://www.apache.org/).
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   */
  
  package com.RuntimeCollective.webapps.tag;
  
  import com.RuntimeCollective.webapps.RuntimeParameters;
  import com.RuntimeCollective.webapps.bean.EntityBean;
  
  import java.lang.reflect.Method;
  import java.lang.reflect.InvocationTargetException;
  import java.sql.SQLException;
  import java.util.Collection;
  import javax.servlet.jsp.JspException;
  import javax.servlet.jsp.JspWriter;
  import javax.servlet.jsp.PageContext;
  import javax.servlet.jsp.tagext.TagSupport;
  import org.apache.struts.action.Action;
  import org.apache.struts.action.ActionError;
  import org.apache.struts.action.ActionErrors;
  import org.apache.struts.util.MessageResources;
  
  /** Finds a collection of EntityBean's given the bean type and a named query.
   *
   * <p>The tag uses reflection to call the static finder method for the query
   * on the bean type.  The naming convention for the finder method is:</p>
   *
   * <p><code>public static Collection findQueryName();</code></p>
   *
   * <p>Attributes:</p>
   *
   * <ul>
   *   <li>name - the name of the collection to create.</li>
   *   <li>scope - the scope in which to create the collection. [optional]</li>
   *   <li>type - the subtype of the EntityBean in which the finder is defined.</li>
   *   <li>query - the name of the query to be executed.</li>
   * </ul>
   *
   * <p>For example, the tag:</p>
   *
   * <p><code>&lt;rs:findBeans name=&quot;giraffes&quot; 
   *                           type=&quot;com.RuntimeCollective.webapps.bean.Giraffe&quot; 
   *                           query=&quot;femaleGiraffes&quot; /&gt;</code></p>
   *
   * <p>Would cause a collection called &quot;giraffes&quot; to be defined in
   * page scope which contained the results of executing 
   * Giraffe.findFemaleGiraffes()</p>
   *
   * <p>If an exception is thrown while trying execute the query, the error is 
   * logged and an empty collection is returned to the calling page.</p>
   *
   * @author Lee Denison (lee@runtime-collective.com)
   * @version $Id: FindBeanCollectionTag.java,v 1.3 2003/09/30 15:13:18 joe Exp $
   */
  public final class FindBeanCollectionTag extends TagSupport {
  
      private String name;
      /** get the name. */
      public String getName() { return name; }
      /** set the name. */
      public void setName(String name) { this.name = name; }
  
      private String scope;
      /** get the scope. */
      public String getScope() { return scope; }
      /** set the scope. */
      public void setScope(String scope) { this.scope = scope; }
  
      private String type;
      /** get the type. */
      public String getType() { return type; }
      /** set the type. */
      public void setType(String type) { this.type = type; }
  
     private String query;
     /** get the query. */
     public String getQuery() { return query; }
     /** set the query. */
     public void setQuery(String query) { this.query = query; }
 
     public FindBeanCollectionTag() {
         initialise();
     }
     
     /** Execute the query and define the collection. */
     public int doStartTag() throws JspException {
         ActionErrors errors = new ActionErrors();
 
         try {
             Method finderMethod = getFinder();
             Collection beans = (Collection) finderMethod.invoke(null, null); 
 
             if (null == scope ||
                 scope.equals("page")) {
                 pageContext.setAttribute(name, beans);
             } else if (scope.equals("request")) {
                 pageContext.setAttribute(name, 
                                          beans, 
                                          PageContext.REQUEST_SCOPE);
             } else if (scope.equals("session")) {
                 pageContext.setAttribute(name, 
                                          beans, 
                                          PageContext.SESSION_SCOPE);
             } else if (scope.equals("application")) {
                 pageContext.setAttribute(name, 
                                          beans, 
                                          PageContext.SESSION_SCOPE);
             } else {
                 RuntimeParameters.logError(this, "unknown scope - " + scope);
             }        
         } catch (ClassCastException e) {
             RuntimeParameters.logError(this, 
                                        type + "." + mangleMethodName() +
                                        " does not return a java.util.Collection",
                                        e);     
         } catch (InvocationTargetException e) {
             RuntimeParameters.logError(this, 
                                        "exception thrown in " + 
                                        type + "." + mangleMethodName(),
                                        e.getTargetException());
             // FIXME: Have to print the stack trace of the enclosed exception
             // FIXME  separately because logError doesn't do it.
             e.getTargetException().printStackTrace();
         } catch (NoSuchMethodException e) {
             RuntimeParameters.logError(this, type + "." + mangleMethodName(), e);
         } catch (Exception e) {
             RuntimeParameters.logError(this, e.getMessage(), e);
         }
         
         return (SKIP_BODY);
     }
 
     /** Release any acquired resources. */
     public void release() {
         super.release();
 
         initialise();
     }
 
     private Method getFinder() 
         throws ClassNotFoundException,
                NoSuchMethodException,
                SecurityException {
         Class finderClass = Class.forName(type);
 
         if (null == query) {
             throw new NoSuchMethodException("no method specified");
         }
 
         return finderClass.getMethod(mangleMethodName(), null);
     }
 
     private String mangleMethodName() {
         StringBuffer finderName = new StringBuffer("find");
         finderName.append(Character.toUpperCase(query.charAt(0)));
         finderName.append(query.substring(1));
  
         return finderName.toString();
     }
     
     private void initialise() {
         name = null;
         scope = null;
         type = null;
         query = null;
     }
 }