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Add custom class loader to OCF (odpi#8288)
Signed-off-by: Mandy Chessell <mandy.e.chessell@gmail.com>
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75 changes: 75 additions & 0 deletions
75
...c/main/java/org/odpi/openmetadata/frameworks/connectors/IsolatedConnectorClassLoader.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| /* SPDX-License-Identifier: Apache-2.0 */ | ||
| /* Copyright Contributors to the ODPi Egeria project. */ | ||
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| package org.odpi.openmetadata.frameworks.connectors; | ||
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| import java.io.*; | ||
| import java.net.URL; | ||
| import java.net.URLClassLoader; | ||
| import java.util.jar.JarFile; | ||
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| /** | ||
| * IsolatedConnectorClassLoader is used by a connector provider to create a connector instance that uses class | ||
| * implementations from its own JAR file rather than any class implementations that may have already been loaded. | ||
| */ | ||
| public class IsolatedConnectorClassLoader extends URLClassLoader | ||
| { | ||
| private final ClassLoader defaultClassLoader; | ||
| private final JarFile jarfile; | ||
| private final String jarFileName; | ||
| private final String jarFileSpec; | ||
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| public IsolatedConnectorClassLoader(String jarFileName) throws IOException | ||
| { | ||
| this(jarFileName, | ||
| Thread.currentThread().getContextClassLoader().getParent(), | ||
| Thread.currentThread().getContextClassLoader()); | ||
| } | ||
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| /** | ||
| * Creates a new class loader of the specified name and using the | ||
| * specified parent class loader for delegation. | ||
| * | ||
| * @param jarFileName name of the jar file to load from | ||
| * @param jdkClassLoader the parent class loader for JRE classes | ||
| * @param defaultClassLoader the class loader to use if can not find class in JAR. | ||
| */ | ||
| protected IsolatedConnectorClassLoader(String jarFileName, | ||
| ClassLoader jdkClassLoader, | ||
| ClassLoader defaultClassLoader) throws IOException | ||
| { | ||
| super(new URL[]{}, jdkClassLoader); | ||
| this.defaultClassLoader = defaultClassLoader; | ||
| this. jarFileName = jarFileName; | ||
| this.jarfile = new JarFile(jarFileName); | ||
| super.addURL(new File(jarFileName).toURI().toURL()); | ||
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| this.jarFileSpec = "jar:file:" + jarFileName + "!/"; | ||
| super.addURL(new URL(jarFileSpec)); | ||
| } | ||
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| /** | ||
| * This loads classes from the JDK, then the JAR file, then the default class loader. | ||
| * | ||
| * @param name The <a href="#binary-name">binary name</a> of the class | ||
| * | ||
| * @return loaded class | ||
| * @throws ClassNotFoundException not found on the class path | ||
| */ | ||
| @Override | ||
| public Class<?> loadClass(String name) throws ClassNotFoundException | ||
| { | ||
| try | ||
| { | ||
| return super.findClass(name); | ||
| } | ||
| catch (ClassNotFoundException notFound) | ||
| { | ||
| return defaultClassLoader.loadClass(name); | ||
| } | ||
| } | ||
| } |
133 changes: 133 additions & 0 deletions
133
.../main/java/org/odpi/openmetadata/frameworks/connectors/IsolatedConnectorProviderBase.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,133 @@ | ||
| /* SPDX-License-Identifier: Apache-2.0 */ | ||
| /* Copyright Contributors to the ODPi Egeria project. */ | ||
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| package org.odpi.openmetadata.frameworks.connectors; | ||
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| import java.io.IOException; | ||
| import java.net.MalformedURLException; | ||
| import java.net.URI; | ||
| import java.net.URISyntaxException; | ||
| import java.net.URL; | ||
| import java.nio.file.Paths; | ||
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| /** | ||
| * IsolatedConnectorProviderBase provides extensions to ConnectorProviderBase that uses a custom class loader to | ||
| * load the connector class in getConnector. This custom class loader give preference to the classes in the | ||
| * same JAR file as the connector provider's implementation over other classes on the class path. | ||
| * Note: | ||
| * this process assumes that the connector class is not already loaded through a reference in the connector providers | ||
| * implementation - ie private static final String connectorClassName should be set to a literal string. | ||
| * | ||
| */ | ||
| public class IsolatedConnectorProviderBase extends ConnectorProviderBase | ||
| { | ||
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| /** | ||
| * Use a custom class loader to favour classes that are located in the connector implementation's JAR file. | ||
| * | ||
| * @return class | ||
| * @throws ClassNotFoundException unable to locate a class by that name on the class path | ||
| */ | ||
| protected Class<?> getClassForConnector() throws ClassNotFoundException | ||
| { | ||
| try | ||
| { | ||
| IsolatedConnectorClassLoader isolatedConnectorClassLoader = new IsolatedConnectorClassLoader(this.getJARFileURL(this.getClass())); | ||
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| // return Class.forName(getConnectorClassName(), true, isolatedConnectorClassLoader); | ||
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| return isolatedConnectorClassLoader.loadClass(getConnectorClassName()); | ||
| } | ||
| catch (IOException error) | ||
| { | ||
| throw new ClassNotFoundException("Bad provider class name", error); | ||
| } | ||
| } | ||
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| /** | ||
| * Extract the name of the JAR file from the provider's class. | ||
| * | ||
| * @param providerClass class for this connector provider | ||
| * @return JAR file name in URL form | ||
| * @throws MalformedURLException should not happen - this means the class was not loaded from a JAR file. | ||
| */ | ||
| private String getJARFileURL(Class<?> providerClass) throws MalformedURLException | ||
| { | ||
| URL qualifiedClassURL = providerClass.getResource(providerClass.getSimpleName() + ".class"); | ||
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| if (qualifiedClassURL != null) | ||
| { | ||
| String qualifiedClassName = qualifiedClassURL.toString(); | ||
| String noClassQualifiedName = qualifiedClassName.split("!")[0]; | ||
| String[] noJarQualifiedNameSplit = noClassQualifiedName.split("jar:file:"); | ||
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| String noJarQualifiedName = noJarQualifiedNameSplit[noJarQualifiedNameSplit.length - 1]; | ||
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| return noJarQualifiedName; | ||
| } | ||
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| return null; | ||
| } | ||
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| /** | ||
| * Return the path name of the Connector Provider's JAR file. | ||
| * | ||
| * @return file name of this connector provider's jar file | ||
| */ | ||
| private String getMyJARFilePath() | ||
| { | ||
| try | ||
| { | ||
| return byGetProtectionDomain(this.getClass()); | ||
| } | ||
| catch (Exception error) | ||
| { | ||
| // Cannot get jar file path using byGetProtectionDomain because the runtime does not permit it | ||
| } | ||
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| return byGetResource(this.getClass()); | ||
| } | ||
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| /** | ||
| * This method | ||
| * @param providerClass | ||
| * @return | ||
| * @throws URISyntaxException | ||
| */ | ||
| String byGetProtectionDomain(Class<?> providerClass) throws URISyntaxException | ||
| { | ||
| URL url = providerClass.getProtectionDomain().getCodeSource().getLocation(); | ||
| return Paths.get(url.toURI()).toString(); | ||
| } | ||
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| String byGetResource(Class<?> providerClass) | ||
| { | ||
| final URL classResource = providerClass.getResource(providerClass.getSimpleName() + ".class"); | ||
| if (classResource == null) | ||
| { | ||
| throw new RuntimeException("class resource is null"); | ||
| } | ||
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| final String url = classResource.toString(); | ||
| if (url.startsWith("jar:file:")) | ||
| { | ||
| // extract 'file:......jarName.jar' part from the url string | ||
| String path = url.replaceAll("^jar:(file:.*[.]jar)!/.*", "$1"); | ||
| try | ||
| { | ||
| return Paths.get(new URI(path)).toString(); | ||
| } | ||
| catch (Exception error) | ||
| { | ||
| throw new RuntimeException("Invalid Jar File URL String", error); | ||
| } | ||
| } | ||
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| throw new RuntimeException("Invalid Jar File URL String"); | ||
| } | ||
| } |
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