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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.log4j.config;
19  
20  import java.beans.*;
21  import java.lang.reflect.*;
22  import org.apache.log4j.Priority;
23  import org.apache.log4j.helpers.LogLog;
24  
25  
26  /***
27     Used for inferring configuration information for a log4j's component.
28  
29     @author  Anders Kristensen
30   */
31  public class PropertyGetter {
32    protected static final Object[] NULL_ARG = new Object[] {};
33    protected Object obj;
34    protected PropertyDescriptor[] props;
35  
36    public interface PropertyCallback {
37      void foundProperty(Object obj, String prefix, String name, Object value);
38    }
39  
40    /***
41      Create a new PropertyGetter for the specified Object. This is done
42      in prepartion for invoking {@link
43      #getProperties(PropertyGetter.PropertyCallback, String)} one or
44      more times.
45  
46      @param obj the object for which to set properties */
47    public
48    PropertyGetter(Object obj) throws IntrospectionException {
49      BeanInfo bi = Introspector.getBeanInfo(obj.getClass());
50      props = bi.getPropertyDescriptors();
51      this.obj = obj;
52    }
53  
54    public
55    static
56    void getProperties(Object obj, PropertyCallback callback, String prefix) {
57      try {
58        new PropertyGetter(obj).getProperties(callback, prefix);
59      } catch (IntrospectionException ex) {
60        LogLog.error("Failed to introspect object " + obj, ex);
61      }
62    }
63  
64    public
65    void getProperties(PropertyCallback callback, String prefix) {
66      for (int i = 0; i < props.length; i++) {
67        Method getter = props[i].getReadMethod();
68        if (getter == null) continue;
69        if (!isHandledType(getter.getReturnType())) {
70  	//System.err.println("Ignoring " + props[i].getName() +" " + getter.getReturnType());
71  	continue;
72        }
73        String name = props[i].getName();
74        try {
75  	Object result = getter.invoke(obj, NULL_ARG);
76  	//System.err.println("PROP " + name +": " + result);
77  	if (result != null) {
78  	  callback.foundProperty(obj, prefix, name, result);
79  	}
80        } catch (Exception ex) {
81  	LogLog.warn("Failed to get value of property " + name);
82        }
83      }
84    }
85  
86    protected
87    boolean isHandledType(Class type) {
88      return String.class.isAssignableFrom(type) ||
89        Integer.TYPE.isAssignableFrom(type) ||
90        Long.TYPE.isAssignableFrom(type)    ||
91        Boolean.TYPE.isAssignableFrom(type) ||
92        Priority.class.isAssignableFrom(type);
93    }
94  }