JavaBeanDataModel


1   /*
2    * $Id: JavaBeanDataModel.java,v 1.1.1.1 2004/06/16 01:43:39 davidson1 Exp $
3    *
4    * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
5    * Santa Clara, California 95054, U.S.A. All rights reserved.
6    */
7   
8   package org.jdesktop.swing.data;
9   
10  import java.beans.BeanInfo  ;
11  import java.beans.Introspector  ;
12  import java.beans.IntrospectionException  ;
13  import java.beans.PropertyDescriptor  ;
14  
15  import java.lang.reflect.Method  ;
16  
17  /**
18   * A class that creates a collection of MetaData based BeanInfo
19   * PropertyDescriptors. To use this class:
20   * <ol>
21   *   <li>Construct the model using the Bean class you wish to model
22   *   <li>use <code>setJavaBean</code> to set the current object of this class.
23   *   <li>Updates made to the form will update the property values of the bean.
24   * </ol>
25   * <p>
26   * TODO: Using JavaBeans as a data source should be generalized and not
27   * constrained to FormModels.
28   *
29   * @author Mark Davidson
30   */
31  public class JavaBeanDataModel extends DefaultDataModel {
32  
33      private BeanInfo   info;
34      private Class   beanClass;
35      private Object   bean; // current bean instance
36  
37      public JavaBeanDataModel(Class   beanClass) throws IntrospectionException   {
38          this(beanClass, null);
39      }
40  
41      /**
42       * Constructs a JavaBeanDataModel by introspecting on the class and using the data from
43       * the object as the current bean
44       *
45       * @param beanClass the class to use to introspect properties
46       * @param bean the object where the current values will be retrieved and stored.
47       */
48      public JavaBeanDataModel(Class   beanClass, Object   bean) throws IntrospectionException   {
49          this.beanClass = beanClass;
50      this.bean = bean;
51          info = Introspector.getBeanInfo(beanClass);
52  
53      // 
54          PropertyDescriptor  [] props = info.getPropertyDescriptors();
55          for (int i = 0; i < props.length; i++) {
56              addField(new MetaData(props[i].getName(),
57                                      props[i].getPropertyType(),
58                                      props[i].getDisplayName()));
59          }
60      }
61  
62      /**
63       * Set the JavaBean instance that this model will use.
64       */
65      public void setJavaBean(Object   bean) {
66          if (bean != null && bean.getClass() != beanClass) {
67              throw new RuntimeException  ("ERROR: argument is not a " +
68                                         beanClass.toString());
69          }
70  
71          Object   oldBean = this.bean;
72          this.bean = bean;
73          if (bean != oldBean) {
74              // Should update all the values
75              String  [] fieldNames = getFieldNames();
76              for (int i = 0; i < fieldNames.length; i++) {
77                  fireValueChanged(fieldNames[i]);
78              }
79          }
80      }
81  
82      /**
83       * Get the JavaBean instance that this model uses.
84       */
85      public Object   getJavaBean() {
86          return bean;
87      }
88  
89      public Object   getValue(String   fieldName) {
90          if (getJavaBean() == null) {
91              return null;
92          }
93          PropertyDescriptor   prop = getPropertyDescriptor(fieldName);
94          Method   readMethod = prop.getReadMethod();
95          if (readMethod != null) {
96              try {
97                  return readMethod.invoke(getJavaBean(), new Object  [0]);
98              }
99              catch (Exception   ex) {
100                 // XXX excecption for illegal access, etc..
101                 ex.printStackTrace();
102             }
103         }
104         return null;
105     }
106 
107     // XXX should be protected.
108     protected void setValueImpl(String   fieldName, Object   value) {
109         if (getJavaBean() == null) {
110             return;
111         }
112         PropertyDescriptor   prop = getPropertyDescriptor(fieldName);
113         Method   writeMethod = prop.getWriteMethod();
114         if (writeMethod != null) {
115             try {
116                 writeMethod.invoke(getJavaBean(), new Object  [] {value});
117             }
118             catch (Exception   ex) {
119                 // XXX excecption for illegal access, etc..
120                 ex.printStackTrace();
121             }
122         }
123     }
124 
125     private PropertyDescriptor   getPropertyDescriptor(String   name) {
126         PropertyDescriptor   pd = null;
127         PropertyDescriptor  [] desc = info.getPropertyDescriptors();
128         for (int i = 0; i < desc.length; i++) {
129             if (name.equals(desc[i].getName())) {
130                 pd = desc[i];
131                 break;
132             }
133         }
134         return pd;
135     }
136 }
137
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