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Java > Open Source Codes > org > apache > ojb > broker > metadata > fieldaccess > PersistentFieldBase


1 package org.apache.ojb.broker.metadata.fieldaccess;
2
3 /* Copyright 2003-2005 The Apache Software Foundation
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * 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 import java.lang.reflect.Field JavaDoc;
19 import java.util.ArrayList JavaDoc;
20 import java.util.List JavaDoc;
21
22 import org.apache.commons.lang.StringUtils;
23 import org.apache.commons.lang.SystemUtils;
24 import org.apache.commons.lang.builder.ToStringBuilder;
25 import org.apache.ojb.broker.metadata.MetadataException;
26 import org.apache.ojb.broker.util.logging.Logger;
27 import org.apache.ojb.broker.util.logging.LoggerFactory;
28
29 /**
30  * Abstract {@link PersistentField} base implementation class.
31  *
32  * @author <a HREF="mailto:armin@codeAuLait.de">Armin Waibel</a>
33  * @version $Id: PersistentFieldBase.java,v 1.2.2.3 2005/12/21 22:26:41 tomdz Exp $
34  */
35 public abstract class PersistentFieldBase implements PersistentField
36 {
37     public static final String JavaDoc PATH_TOKEN = "::";
38
39     private String JavaDoc fieldName;
40     protected Class JavaDoc rootObjectType;
41
42     /**
43      * For internal use only!!
44      * TODO: Default constructor only needed to support
45      * PersistentFieldFactory#usesAccessorsAndMutators()
46      * method - find a better solution. Make 'public' to
47      * allow helper class to instantiate class.
48      */
49     public PersistentFieldBase()
50     {
51     }
52
53     public PersistentFieldBase(Class JavaDoc clazz, String JavaDoc fieldname)
54     {
55         this.rootObjectType = clazz;
56         this.fieldName = fieldname;
57     }
58
59     /**
60      * A value of true indicates that this field should
61      * suppress Java language access checking when it is used.
62      */
63     protected abstract boolean makeAccessible();
64
65     public String JavaDoc getName()
66     {
67         return fieldName;
68     }
69
70     public Class JavaDoc getDeclaringClass()
71     {
72         return rootObjectType;
73     }
74
75     protected List JavaDoc getFieldGraph(boolean makeAccessible)
76     {
77         List JavaDoc result = new ArrayList JavaDoc();
78         String JavaDoc[] fields = StringUtils.split(getName(), PATH_TOKEN);
79         Field JavaDoc fld = null;
80         for (int i = 0; i < fields.length; i++)
81         {
82             String JavaDoc fieldName = fields[i];
83             try
84             {
85                 if (fld == null)
86                 {
87                     fld = getFieldRecursive(rootObjectType, fieldName);
88                 }
89                 else
90                 {
91                     fld = getFieldRecursive(fld.getType(), fieldName);
92                 }
93                 if (makeAccessible)
94                 {
95                     fld.setAccessible(true);
96                 }
97             }
98             catch (NoSuchFieldException JavaDoc e)
99             {
100                 throw new MetadataException("Can't find member '"
101                         + fieldName + "' in class " + (fld != null ? fld.getDeclaringClass() : rootObjectType), e);
102             }
103             result.add(fld);
104         }
105         return result;
106     }
107
108     /**
109      * try to find a field in class c, recurse through class hierarchy if necessary
110      *
111      * @throws NoSuchFieldException if no Field was found into the class hierarchy
112      */
113     private Field JavaDoc getFieldRecursive(Class JavaDoc c, String JavaDoc name) throws NoSuchFieldException JavaDoc
114     {
115         try
116         {
117             return c.getDeclaredField(name);
118         }
119         catch (NoSuchFieldException JavaDoc e)
120         {
121             // if field could not be found in the inheritance hierarchy, signal error
122 if ((c == Object JavaDoc.class) || (c.getSuperclass() == null) || c.isInterface())
123             {
124                 throw e;
125             }
126             // if field could not be found in class c try in superclass
127 else
128             {
129                 return getFieldRecursive(c.getSuperclass(), name);
130             }
131         }
132     }
133
134     protected Logger getLog()
135     {
136         return LoggerFactory.getLogger("PersistentField");
137     }
138
139     public String JavaDoc toString()
140     {
141         ToStringBuilder buf = new ToStringBuilder(this);
142         buf.append("rootType", rootObjectType);
143         buf.append("fieldName", fieldName);
144         return buf.toString();
145     }
146
147     /**
148      * Build a String representation of given arguments.
149      */
150     protected String JavaDoc buildErrorSetMsg(Object JavaDoc obj, Object JavaDoc value, Field JavaDoc aField)
151     {
152         String JavaDoc eol = SystemUtils.LINE_SEPARATOR;
153         StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
154         buf
155                 .append(eol + "[try to set 'object value' in 'target object'")
156                 .append(eol + "target obj class: " + (obj != null ? obj.getClass().getName() : null))
157                 .append(eol + "target field name: " + (aField != null ? aField.getName() : null))
158                 .append(eol + "target field type: " + (aField != null ? aField.getType() : null))
159                 .append(eol + "target field declared in: " + (aField != null ? aField.getDeclaringClass().getName() : null))
160                 .append(eol + "object value class: " + (value != null ? value.getClass().getName() : null))
161                 .append(eol + "object value: " + (value != null ? value : null))
162                 .append(eol + "]");
163         return buf.toString();
164     }
165
166     /**
167      * Build a String representation of given arguments.
168      */
169     protected String JavaDoc buildErrorGetMsg(Object JavaDoc obj, Field JavaDoc aField)
170     {
171         String JavaDoc eol = SystemUtils.LINE_SEPARATOR;
172         StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
173         buf
174                 .append(eol + "[try to read from source object")
175                 .append(eol + "source obj class: " + (obj != null ? obj.getClass().getName() : null))
176                 .append(eol + "target field name: " + (aField != null ? aField.getName() : null))
177                 .append(eol + "target field type: " + (aField != null ? aField.getType() : null))
178                 .append(eol + "target field declared in: " + (aField != null ? aField.getDeclaringClass().getName() : null))
179                 .append(eol + "]");
180         return buf.toString();
181     }
182 }
183
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