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java/org/apache/tomcat/util/digester/ObjectCreateRule.java

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+/*
+ * 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.tomcat.util.digester;
+
+
+import org.xml.sax.Attributes;
+
+
+/**
+ * Rule implementation that creates a new object and pushes it
+ * onto the object stack.  When the element is complete, the
+ * object will be popped
+ */
+
+public class ObjectCreateRule extends Rule {
+
+
+    // ----------------------------------------------------------- Constructors
+
+
+    /**
+     * Construct an object create rule with the specified class name.
+     *
+     * @param className Java class name of the object to be created
+     */
+    public ObjectCreateRule(String className) {
+
+        this(className, (String) null);
+
+    }
+
+
+    /**
+     * Construct an object create rule with the specified class name and an
+     * optional attribute name containing an override.
+     *
+     * @param className Java class name of the object to be created
+     * @param attributeName Attribute name which, if present, contains an
+     *  override of the class name to create
+     */
+    public ObjectCreateRule(String className,
+                            String attributeName) {
+
+        this.className = className;
+        this.attributeName = attributeName;
+
+    }
+
+
+    // ----------------------------------------------------- Instance Variables
+
+    /**
+     * The attribute containing an override class name if it is present.
+     */
+    protected String attributeName = null;
+
+
+    /**
+     * The Java class name of the object to be created.
+     */
+    protected String className = null;
+
+
+    // --------------------------------------------------------- Public Methods
+
+
+    /**
+     * Process the beginning of this element.
+     *
+     * @param namespace the namespace URI of the matching element, or an
+     *   empty string if the parser is not namespace aware or the element has
+     *   no namespace
+     * @param name the local name if the parser is namespace aware, or just
+     *   the element name otherwise
+     * @param attributes The attribute list for this element
+     */
+    @Override
+    public void begin(String namespace, String name, Attributes attributes)
+            throws Exception {
+
+        // Identify the name of the class to instantiate
+        String realClassName = className;
+        if (attributeName != null) {
+            String value = attributes.getValue(attributeName);
+            if (value != null) {
+                realClassName = value;
+            }
+        }
+        if (digester.log.isDebugEnabled()) {
+            digester.log.debug("[ObjectCreateRule]{" + digester.match +
+                    "}New " + realClassName);
+        }
+
+        if (realClassName == null) {
+            throw new NullPointerException("No class name specified for " +
+                    namespace + " " + name);
+        }
+
+        // Instantiate the new object and push it on the context stack
+        Class<?> clazz = digester.getClassLoader().loadClass(realClassName);
+        Object instance = clazz.getConstructor().newInstance();
+        digester.push(instance);
+    }
+
+
+    /**
+     * Process the end of this element.
+     *
+     * @param namespace the namespace URI of the matching element, or an
+     *   empty string if the parser is not namespace aware or the element has
+     *   no namespace
+     * @param name the local name if the parser is namespace aware, or just
+     *   the element name otherwise
+     */
+    @Override
+    public void end(String namespace, String name) throws Exception {
+
+        Object top = digester.pop();
+        if (digester.log.isDebugEnabled()) {
+            digester.log.debug("[ObjectCreateRule]{" + digester.match +
+                    "} Pop " + top.getClass().getName());
+        }
+
+    }
+
+
+    /**
+     * Render a printable version of this Rule.
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder("ObjectCreateRule[");
+        sb.append("className=");
+        sb.append(className);
+        sb.append(", attributeName=");
+        sb.append(attributeName);
+        sb.append("]");
+        return sb.toString();
+    }
+
+
+}