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Java > Open Source Codes > org > apache > cayenne > jpa > conf > EntityMapXMLLoader


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19
20 package org.apache.cayenne.jpa.conf;
21
22 import java.io.IOException JavaDoc;
23 import java.io.InputStreamReader JavaDoc;
24 import java.io.Reader JavaDoc;
25 import java.net.URL JavaDoc;
26
27 import javax.xml.XMLConstants JavaDoc;
28 import javax.xml.parsers.SAXParserFactory JavaDoc;
29 import javax.xml.transform.stream.StreamSource JavaDoc;
30 import javax.xml.validation.Schema JavaDoc;
31 import javax.xml.validation.SchemaFactory JavaDoc;
32
33 import org.apache.cayenne.jpa.map.JpaEntityMap;
34 import org.apache.cayenne.xml.XMLDecoder;
35 import org.xml.sax.SAXException JavaDoc;
36
37 /**
38  * {@link org.apache.cayenne.jpa.map.JpaEntityMap} loader that reads mapping information
39  * from the XML sources compatible with the JPA ORM schema.
40  *
41  * @author Andrus Adamchik
42  */
43 public class EntityMapXMLLoader {
44
45     static final String JavaDoc XML_CODER_MAPPING = "META-INF/cayenne/orm-coder.xml";
46     static final String JavaDoc ORM_SCHEMA = "META-INF/schemas/orm_1_0.xsd";
47
48     Schema JavaDoc schema;
49
50     protected ClassLoader JavaDoc classLoader;
51
52     public EntityMapXMLLoader() {
53         this(Thread.currentThread().getContextClassLoader(), false);
54     }
55
56     public EntityMapXMLLoader(ClassLoader JavaDoc classLoader, boolean validateDescriptors) {
57
58         this.classLoader = classLoader;
59
60         // TODO: andrus, 04/18/2006 - merge validation capabilities to the XMLDecoder...
61 if (validateDescriptors) {
62             SAXParserFactory JavaDoc parserFactory = SAXParserFactory.newInstance();
63             parserFactory.setNamespaceAware(true);
64
65             // note that validation requires that orm.xml declares a schema like this:
66 // <orm xmlns="http://java.sun.com/xml/ns/persistence/orm"
67 // xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
68 // xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm
69 // http://java.sun.com/xml/ns/persistence/orm/orm_1_0.xsd">
70
71             URL JavaDoc schemaURL = classLoader.getResource(ORM_SCHEMA);
72
73             SchemaFactory JavaDoc factory = SchemaFactory
74                     .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
75             StreamSource JavaDoc ss = new StreamSource JavaDoc(schemaURL.toExternalForm());
76
77             try {
78                 this.schema = factory.newSchema(ss);
79             }
80             catch (Exception JavaDoc e) {
81                 throw new RuntimeException JavaDoc("Error loading ORM schema", e);
82             }
83         }
84     }
85
86     /**
87      * Loads {@link JpaEntityMap} using provided class loader to locate the XML. Returns
88      * null if no mapping is found.
89      */
90
91     public JpaEntityMap getEntityMap(URL JavaDoc resource) {
92
93         // TODO: andrus, 04/18/2006 XMLDecoder should support classpath locations for
94 // mapping descriptors
95 URL JavaDoc mappingURL = classLoader.getResource(XML_CODER_MAPPING);
96         if (mappingURL == null) {
97             throw new RuntimeException JavaDoc("No code mapping found: " + XML_CODER_MAPPING);
98         }
99
100         validate(resource);
101
102         try {
103
104             Reader JavaDoc in = new InputStreamReader JavaDoc(resource.openStream(), "UTF-8");
105
106             // TODO: andrus, 04/18/2006 - an inefficiency in XMLDecoder - it
107 // doesn't cache the mapping
108
109             XMLDecoder decoder = new XMLDecoder();
110             JpaEntityMap entityMap = (JpaEntityMap) decoder.decode(in, mappingURL
111                     .toExternalForm());
112
113             return entityMap;
114         }
115         catch (Exception JavaDoc e) {
116             throw new RuntimeException JavaDoc("Error processing ORM mapping " + resource, e);
117         }
118     }
119
120     // TODO: andrus, 04/18/2006 - move schema validation to the XMLDecoder
121 void validate(URL JavaDoc resource) {
122         if (schema != null) {
123             try {
124                 schema.newValidator().validate(new StreamSource JavaDoc(resource.openStream()));
125             }
126             catch (SAXException JavaDoc e) {
127                 throw new RuntimeException JavaDoc("Error validating ORM mapping " + resource, e);
128             }
129             catch (IOException JavaDoc e) {
130                 throw new RuntimeException JavaDoc("Error processing ORM mapping " + resource, e);
131             }
132         }
133     }
134 }
135
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