Initial revision

From-SVN: r102074

libjava/classpath/gnu/java/beans/decoder/SimpleHandler.java

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+/* gnu.java.beans.decoder.SimpleHandler
+   Copyright (C) 2004 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+ 
+GNU Classpath 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
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package gnu.java.beans.decoder;
+
+import java.beans.ExceptionListener;
+
+import org.xml.sax.Attributes;
+
+/** XML element handler that is specialized on tags that contains a simple string in their
+ * body which has to be parsed in a specific way.
+ * <p>All of these tags have in common that they do not accept attributes. A warning is
+ * send to the parser's ExceptionListener when one or more attributes exist.</p>
+ *
+ * @author Robert Schuster
+ */
+abstract class SimpleHandler extends AbstractElementHandler
+{
+  private ObjectContext context;
+
+  /**
+   * @param PersistenceParser
+   */
+  SimpleHandler(ElementHandler parent)
+  {
+    super(parent, false);
+
+    // SimpleHandler do not accept any subelements
+  }
+
+  protected final Context startElement(Attributes attributes, ExceptionListener exceptionListener)
+    throws AssemblyException
+  {
+  	
+    // note: simple elements should not have any attributes. We inform
+    // the user of this syntactical but uncritical problem by sending
+    // an IllegalArgumentException for each unneccessary attribute
+    int size = attributes.getLength();
+    for (int i = 0; i < size; i++) {
+            String attributeName = attributes.getQName(i);
+            Exception e =
+                    new IllegalArgumentException(
+                            "Unneccessary attribute '"
+                                    + attributeName
+                                    + "' discarded.");
+            exceptionListener.exceptionThrown(e);
+    }
+    
+    return context = new ObjectContext();
+  }
+
+  public void endElement(String characters)
+    throws AssemblyException, AssemblyException
+  {
+    // reports the number when the character data can be parsed
+    try
+      {
+	context.setObject(parse(characters));
+      }
+    catch (NumberFormatException nfe)
+      {
+	throw new AssemblyException(nfe);
+      }
+  }
+
+  /** Returns an object that is created from the given characters. If the string is
+   * converted into a number a NumberFormatException is cathed and reported
+   * appropriately.
+   *
+   * @param characters A string of characters that has to be processed in some way.
+   * @return An Object instance generated from the given data.
+   * @throws AssemblerException When the string was invalid.
+   * @throws NumberFormatException When the string could not be parsed into a number.
+   */
+  protected abstract Object parse(String characters)
+    throws AssemblyException, NumberFormatException;
+}