1 // $Id: Persistence.java 11171 2007-02-08 03:40:51Z epbernard $
2 package javax.persistence;
3
4 import java.io.BufferedReader;
5 import java.io.IOException;
6 import java.io.InputStream;
7 import java.io.InputStreamReader;
8 import java.net.URL;
9 import java.util.Enumeration;
10 import java.util.HashSet;
11 import java.util.Map;
12 import java.util.Set;
13 import java.util.regex.Matcher;
14 import java.util.regex.Pattern;
15 import javax.persistence.spi.PersistenceProvider;
16
17 /**
18 * Bootstrap class that provides access to an EntityManagerFactory.
19 */
20 public class Persistence {
21
22 public static String PERSISTENCE_PROVIDER = PersistenceProvider.class.getName();
23
24 protected static final Set<PersistenceProvider> providers = new HashSet<PersistenceProvider>();
25
26 /**
27 * Create and return an EntityManagerFactory for the named persistence unit.
28 *
29 * @param persistenceUnitName The name of the persistence unit
30 * @return The factory that creates EntityManagers configured according to the specified persistence unit
31 */
32 public static EntityManagerFactory createEntityManagerFactory(String persistenceUnitName) {
33 return createEntityManagerFactory( persistenceUnitName, null );
34 }
35
36 /**
37 * Create and return an EntityManagerFactory for the named persistence unit using the given properties.
38 *
39 * @param persistenceUnitName The name of the persistence unit
40 * @param properties Additional properties to use when creating the factory. The values of these properties override
41 * any values that may have been configured elsewhere
42 * @return The factory that creates EntityManagers configured according to the specified persistence unit
43 */
44 public static EntityManagerFactory createEntityManagerFactory(String persistenceUnitName, Map properties) {
45 EntityManagerFactory emf = null;
46
47 if ( providers.size() == 0 ) {
48 findAllProviders();
49 }
50 for ( PersistenceProvider provider : providers ) {
51 emf = provider.createEntityManagerFactory( persistenceUnitName, properties );
52 if ( emf != null ) break;
53 }
54 if ( emf == null ) {
55 throw new PersistenceException( "No Persistence provider for EntityManager named " + persistenceUnitName );
56 }
57 return emf;
58 }
59
60 // Helper methods
61
62 private static void findAllProviders() {
63 try {
64 ClassLoader loader = Thread.currentThread().getContextClassLoader();
65 Enumeration<URL> resources = loader.getResources( "META-INF/services/" + PersistenceProvider.class.getName() );
66 Set<String> names = new HashSet<String>();
67 while ( resources.hasMoreElements() ) {
68 URL url = resources.nextElement();
69 InputStream is = url.openStream();
70 try {
71 names.addAll( providerNamesFromReader( new BufferedReader( new InputStreamReader( is ) ) ) );
72 }
73 finally {
74 is.close();
75 }
76 }
77 for ( String s : names ) {
78 Class providerClass = loader.loadClass( s );
79 providers.add( (PersistenceProvider) providerClass.newInstance() );
80 }
81 }
82 catch (IOException e) {
83 throw new PersistenceException( e );
84 }
85 catch (InstantiationException e) {
86 throw new PersistenceException( e );
87 }
88 catch (IllegalAccessException e) {
89 throw new PersistenceException( e );
90 }
91 catch (ClassNotFoundException e) {
92 throw new PersistenceException( e );
93 }
94 }
95
96 private static final Pattern nonCommentPattern = Pattern.compile( "^([^#]+)" );
97
98 private static Set<String> providerNamesFromReader(BufferedReader reader) throws IOException {
99 Set<String> names = new HashSet<String>();
100 String line;
101 while ( ( line = reader.readLine() ) != null ) {
102 line = line.trim();
103 Matcher m = nonCommentPattern.matcher( line );
104 if ( m.find() ) {
105 names.add( m.group().trim() );
106 }
107 }
108 return names;
109 }
110 }
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