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Diffstat (limited to 'tags/java-stable-20060304/spec/sdo/src/main/java/commonj/sdo/impl/HelperProvider.java')
| -rw-r--r-- | tags/java-stable-20060304/spec/sdo/src/main/java/commonj/sdo/impl/HelperProvider.java | 365 |
1 files changed, 0 insertions, 365 deletions
diff --git a/tags/java-stable-20060304/spec/sdo/src/main/java/commonj/sdo/impl/HelperProvider.java b/tags/java-stable-20060304/spec/sdo/src/main/java/commonj/sdo/impl/HelperProvider.java deleted file mode 100644 index 9f1f0d4642..0000000000 --- a/tags/java-stable-20060304/spec/sdo/src/main/java/commonj/sdo/impl/HelperProvider.java +++ /dev/null @@ -1,365 +0,0 @@ -/** - * - * Copyright 2006 The Apache Software Foundation - * - * Licensed under the Apache License, Version 2.0 (the "License"); - * you may not use this file except in compliance with the License. - * You may obtain a copy of the License at - * - * http://www.apache.org/licenses/LICENSE-2.0 - * - * Unless required by applicable law or agreed to in writing, software - * distributed under the License is distributed on an "AS IS" BASIS, - * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - * See the License for the specific language governing permissions and - * limitations under the License. - */ - -package commonj.sdo.impl; - -import java.io.BufferedReader; -import java.io.IOException; -import java.io.InputStream; -import java.io.InputStreamReader; -import java.io.UnsupportedEncodingException; -import java.security.AccessController; -import java.security.PrivilegedAction; - -import commonj.sdo.helper.CopyHelper; -import commonj.sdo.helper.DataFactory; -import commonj.sdo.helper.DataHelper; -import commonj.sdo.helper.EqualityHelper; -import commonj.sdo.helper.TypeHelper; -import commonj.sdo.helper.XMLHelper; -import commonj.sdo.helper.XSDHelper; - -/** - * A HelperProvider obtains specific default helpers and other - * implementation-specific objects used by a Java implementation of SDO. - * - * @version $Rev$ $Date$ - */ -public abstract class HelperProvider { - /** - * The default HelperProvider INSTANCE. This is located using the ClassLoader used - * to load the HelperProvider class itself and if no default implementation is available - * this field will be set to null. - */ - public static final HelperProvider INSTANCE; - - /** - * The name of the resource that is used for service location. - */ - public static final String SERVICE_RESOURCE_NAME = "META-INF/services/commonj.sdo.impl.HelperProvider"; - - /** - * The name of the system property that will be checked for an implementation name. - */ - public static final String PROPERTY_NAME = "commonj.sdo.impl.HelperProvider"; - - static { - // initialize the default instance using this class's classloader - // set to null if none could be located (implies no default implementation) - HelperProvider provider; - try { - provider = getInstance(HelperProvider.class.getClassLoader()); - } catch (NoHelperProviderException e) { - provider = null; - } - INSTANCE = provider; - } - - /** - * Locate and instantiate a HelperProvider. - * <p/> - * Attempt to locate a HelperProvider using first the Thread's current context classloader and then, - * if that is not set, not readable, or does not provide an implementation, using the classloader - * used to load the HelperProvider class itself. - * <p/> - * A new instance is returned for each sucessful invocation. - * - * @return an implementation of HelperProvider - * @throws NoHelperProviderException if no provider implementation was defined or it could not be instantiated - */ - public static HelperProvider getInstance() throws NoHelperProviderException { - String implName = getImplementationName(); - - ClassLoader cl = getContextClassLoader(); - if (cl != null) { - HelperProvider provider = loadImplementation(cl, implName); - if (provider != null) { - return provider; - } - } - - cl = HelperProvider.class.getClassLoader(); - HelperProvider provider = loadImplementation(cl, implName); - if (provider != null) { - return provider; - } - - throw new NoHelperProviderException(implName); - } - - - /** - * Locate and instantiate a HelperProvider using the supplied ClassLoader. - * <p/> - * The name of the implementation to use is determined by the value of the "commonj.sdo.impl.HelperProvider" - * system property. If this is not set or this code does not have permission to read it then the name - * will be retrieved from the META-INF/services/commonj.sdo.impl.HelperProvider resource as returned - * by the supplied classloader as described in the - * <a href="http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html#Service%20Provider">JAR file specification</a>. - * <p/> - * A new instance is returned for each sucessful invocation. - * - * @param cl the classloader to use to locate and instantiate the implementation - * @return the specified implementation of HelperProvider - * @throws NoHelperProviderException if no provider implementation was defined or it could not be instantiated - */ - public static HelperProvider getInstance(ClassLoader cl) throws NoHelperProviderException { - String implName = getImplementationName(); - HelperProvider provider = loadImplementation(cl, implName); - if (provider == null) { - throw new NoHelperProviderException(implName); - } - return provider; - } - - private static ClassLoader getContextClassLoader() { - try { - return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() { - public ClassLoader run() { - return Thread.currentThread().getContextClassLoader(); - } - }); - } catch (SecurityException e) { - return null; - } - } - - private static HelperProvider loadImplementation(ClassLoader cl, String implName) throws NoHelperProviderException { - // if no name is requested, locate using the supplied classloader - if (implName == null) { - implName = getImplementationName(cl); - } - // no implementation to try, return null - if (implName == null) { - return null; - } - - // try an instantiate the implementation - try { - return (HelperProvider) cl.loadClass(implName).newInstance(); - } catch (InstantiationException e) { - throw new NoHelperProviderException(implName, e); - } catch (IllegalAccessException e) { - throw new NoHelperProviderException(implName, e); - } catch (ClassNotFoundException e) { - throw new NoHelperProviderException(implName, e); - } - } - - private static String getImplementationName() { - try { - return AccessController.doPrivileged(new PrivilegedAction<String>() { - @SuppressWarnings({"AccessOfSystemProperties"}) - public String run() { - return System.getProperty(PROPERTY_NAME); - } - }); - } catch (SecurityException e) { - return null; - } - } - - private static String getImplementationName(ClassLoader cl) { - InputStream is = cl.getResourceAsStream(SERVICE_RESOURCE_NAME); - if (is == null) { - return null; - } - - InputStreamReader in; - try { - in = new InputStreamReader(is, "UTF-8"); - } catch (UnsupportedEncodingException e) { - throw new AssertionError("UTF-8 encoding not available"); - } - - try { - BufferedReader reader = new BufferedReader(in, 128); - try { - String line; - while ((line = reader.readLine()) != null) { - int i = line.indexOf('#'); - if (i != -1) { - line = line.substring(0, i); - } - line = line.trim(); - if (line.length() > 0) { - return line; - } - } - return null; - } finally { - reader.close(); - } - } catch (IOException e) { - throw new NoHelperProviderException(e); - } - } - - - /////////////////////////////////////////////////////////////////////////////////////////////////////////////////// - // implementation specific methods for users that don't want to use the default implementation - - /** - * Returns a CopyHelper obtained from this implementation. - * - * @return a CopyHelper obtained from this implementation - */ - public abstract CopyHelper copyHelper(); - - /** - * Returns a DataFactory obtained from this implementation. - * - * @return a DataFactory obtained from this implementation - */ - public abstract DataFactory dataFactory(); - - /** - * Returns a DataHelper obtained from this implementation. - * - * @return a DataHelper obtained from this implementation - */ - public abstract DataHelper dataHelper(); - - /** - * Returns a EqualityHelper obtained from this implementation. - * - * @return a EqualityHelper obtained from this implementation - */ - public abstract EqualityHelper equalityHelper(); - - /** - * Returns a TypeHelper obtained from this implementation. - * - * @return a TypeHelper obtained from this implementation - */ - public abstract TypeHelper typeHelper(); - - /** - * Returns a XMLHelper obtained from this implementation. - * - * @return a XMLHelper obtained from this implementation - */ - public abstract XMLHelper xmlHelper(); - - /** - * Returns a XSDHelper obtained from this implementation. - * - * @return a XSDHelper obtained from this implementation - */ - public abstract XSDHelper xsdHelper(); - - /** - * Create a Resolvable using this implementation - * - * @return a Resolvable created using this implementation - */ - public abstract ExternalizableDelegator.Resolvable resolvable(); - - /** - * Create a Resolvable using this implementation - * - * @param target the object to be resolved - * @return a Resolvable created using this implementation - */ - public abstract ExternalizableDelegator.Resolvable resolvable(Object target); - - - /////////////////////////////////////////////////////////////////////////////////////////////////////////////////// - // static helper methods required by the specification - - /** - * Returns a CopyHelper obtained from the default HelperProvider. - * - * @return a CopyHelper obtained from the default HelperProvider - */ - public static CopyHelper getCopyHelper() { - return INSTANCE.copyHelper(); - } - - /** - * Returns a DataFactory obtained from the default HelperProvider. - * - * @return a DataFactory obtained from the default HelperProvider - */ - public static DataFactory getDataFactory() { - return INSTANCE.dataFactory(); - } - - /** - * Returns a DataHelper obtained from the default HelperProvider. - * - * @return a DataHelper obtained from the default HelperProvider - */ - public static DataHelper getDataHelper() { - return INSTANCE.dataHelper(); - } - - /** - * Returns a EqualityHelper obtained from the default HelperProvider. - * - * @return a EqualityHelper obtained from the default HelperProvider - */ - public static EqualityHelper getEqualityHelper() { - return INSTANCE.equalityHelper(); - } - - /** - * Returns a TypeHelper obtained from the default HelperProvider. - * - * @return a TypeHelper obtained from the default HelperProvider - */ - public static TypeHelper getTypeHelper() { - return INSTANCE.typeHelper(); - } - - /** - * Returns a XMLHelper obtained from the default HelperProvider. - * - * @return a XMLHelper obtained from the default HelperProvider - */ - public static XMLHelper getXMLHelper() { - return INSTANCE.xmlHelper(); - } - - /** - * Returns a XSDHelper obtained from the default HelperProvider. - * - * @return a XSDHelper obtained from the default HelperProvider - */ - public static XSDHelper getXSDHelper() { - return INSTANCE.xsdHelper(); - } - - /** - * Create a Resolvable using the default HelperProvider - * - * @return a Resolvable created using the default HelperProvider - */ - public static ExternalizableDelegator.Resolvable createResolvable() { - return INSTANCE.resolvable(); - } - - /** - * Create a Resolvable using the default HelperProvider - * - * @param target the object to be resolved - * @return a Resolvable created using the default HelperProvider - */ - public static ExternalizableDelegator.Resolvable createResolvable(Object target) { - return INSTANCE.resolvable(target); - } -}
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