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Java > Open Source Codes > org > apache > cayenne > jpa > instrument > UnitClassTransformer


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19 package org.apache.cayenne.jpa.instrument;
20
21 import java.lang.instrument.ClassFileTransformer JavaDoc;
22 import java.lang.instrument.IllegalClassFormatException JavaDoc;
23 import java.security.ProtectionDomain JavaDoc;
24 import java.util.Map JavaDoc;
25
26 import javax.persistence.spi.ClassTransformer;
27
28 import org.apache.cayenne.jpa.map.JpaClassDescriptor;
29 import org.apache.commons.logging.Log;
30 import org.apache.commons.logging.LogFactory;
31
32 /**
33  * A ClassFileTransformer decorator that wraps a Java instrumentation ClassFileTransformer
34  * instance in a JPA ClassTransformer. UnitClassTranformer would only do transformation of
35  * the mapped classes.
36  *
37  * @author Andrus Adamchik
38  */
39 public class UnitClassTransformer implements ClassTransformer {
40
41     protected ClassLoader JavaDoc tempClassLoader;
42     protected Log logger;
43     protected ClassFileTransformer JavaDoc transformer;
44     protected Map JavaDoc<String JavaDoc, JpaClassDescriptor> managedClasses;
45
46     public UnitClassTransformer(Map JavaDoc<String JavaDoc, JpaClassDescriptor> managedClasses,
47             ClassLoader JavaDoc tempClassLoader, ClassFileTransformer JavaDoc transformer) {
48         this.transformer = transformer;
49         this.managedClasses = managedClasses;
50         this.tempClassLoader = tempClassLoader;
51         this.logger = LogFactory.getLog(getClass());
52     }
53
54     public byte[] transform(
55             ClassLoader JavaDoc loader,
56             String JavaDoc className,
57             Class JavaDoc<?> classBeingRedefined,
58             ProtectionDomain JavaDoc protectionDomain,
59             byte[] classfileBuffer) throws IllegalClassFormatException JavaDoc {
60
61         if (tempClassLoader == loader) {
62             return null;
63         }
64
65         if (isManagedClass(className)) {
66             logger.warn("Will transform: " + className);
67
68             return transformer.transform(
69                     loader,
70                     className,
71                     classBeingRedefined,
72                     protectionDomain,
73                     classfileBuffer);
74         }
75         else {
76             return null;
77         }
78     }
79
80     /**
81      * Returns true if a classname os a part of an entity map. Note that the class name is
82      * expected in the internal format, separated by "/", not ".".
83      */
84     protected boolean isManagedClass(String JavaDoc className) {
85         return managedClasses.containsKey(className.replace('/', '.'));
86     }
87 }
88
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