CompleteIntrospector


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52  
53  package com.go.trove.util;
54  
55  import java.beans.*;
56  import java.util.*;
57  import java.lang.ref.*;
58  
59  /******************************************************************************
60   * A JavaBean Introspector that ensures interface properties are properly
61   * discovered.
62   * 
63   * @author Brian S O'Neill
64   * @version
65   * <!--$$Revision:--> 1 <!-- $-->, <!--$$JustDate:--> 00/12/13 <!-- $-->
66   */
67  public class CompleteIntrospector {
68      // Weakly maps Class objects to softly referenced PropertyDescriptor maps.
69      private static Map cPropertiesCache;
70  
71      static {
72          cPropertiesCache = new IdentityMap();
73  
74          // The Introspector has a poor design in that a special GLOBAL setting
75          // is used. The default setting has a negative affect because the
76          // BeanInfo search path disregards packages. By default, the search
77          // path provides a BeanInfo for Component, which is for
78          // java.awt.Component. However, any class with this name, in any
79          // package, will be given the visible properties of java.awt.Component.
80          Introspector.setBeanInfoSearchPath(new String  [0]);
81      }
82  
83      /**
84       * Test program.
85       */
86      public static void main(String  [] args) throws Exception   {
87          Map map = getAllProperties(Class.forName(args[0]));
88          Iterator keys = map.keySet().iterator();
89          while (keys.hasNext()) {
90              String   key = (String  )keys.next();
91              PropertyDescriptor desc = (PropertyDescriptor)map.get(key);
92              System.out.println(key + " = " + desc);
93          }
94      }
95  
96      /**
97       * A function that returns a Map of all the available properties on
98       * a given class including write-only properties. The properties returned
99       * is mostly a superset of those returned from the standard JavaBeans 
100      * Introspector except more properties are made available to interfaces.
101      * 
102      * @return an unmodifiable mapping of property names (Strings) to
103      * PropertyDescriptor objects.
104      *
105      */
106     public static Map getAllProperties(Class   clazz)
107         throws IntrospectionException {
108         
109         synchronized (cPropertiesCache) {
110             Map properties;
111 
112             Reference ref = (Reference)cPropertiesCache.get(clazz);
113             if (ref != null) {
114                 properties = (Map)ref.get();
115                 if (properties != null) {
116                     return properties;
117                 }
118                 else {
119                     // Clean up cleared reference.
120                     cPropertiesCache.remove(clazz);
121                 }
122             }
123 
124             properties = Collections.unmodifiableMap(createProperties(clazz));
125             cPropertiesCache.put(clazz, new SoftReference(properties));
126             return properties;
127         }
128     }
129 
130     private static Map createProperties(Class   clazz)
131         throws IntrospectionException {
132 
133         Map properties = new HashMap();
134 
135         if (clazz == null || clazz.isPrimitive()) {
136             return properties;
137         }
138         
139         BeanInfo info;
140         try {
141             info = Introspector.getBeanInfo(clazz);
142         }
143         catch (LinkageError   e) {
144             throw new IntrospectionException(e.toString());
145         }
146 
147         if (info != null) {
148             PropertyDescriptor[] pdArray = info.getPropertyDescriptors();
149             
150             // Standard properties.
151             int length = pdArray.length;
152             for (int i=0; i<length; i++) {
153                 properties.put(pdArray[i].getName(), pdArray[i]);
154             }
155         }
156 
157         // Properties defined in Object are also available to interfaces.
158         if (clazz.isInterface()) {
159             properties.putAll(getAllProperties(Object  .class));
160         }
161 
162         // Ensure that all implemented interfaces are properly analyzed.
163         Class  [] interfaces = clazz.getInterfaces();
164         for (int i=0; i<interfaces.length; i++) {
165             properties.putAll(getAllProperties(interfaces[i]));
166         }
167 
168         // Filter out properties with names that contain '$' characters.
169         Iterator it = properties.keySet().iterator();
170         while (it.hasNext()) {
171             String   propertyName = (String  )it.next();
172             if (propertyName.indexOf('$') >= 0) {
173                 it.remove();
174             }
175         }
176 
177         return properties;
178     }
179 }
180
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