Package org.apache.tika.plugins

Class PluginComponentLoader

java.lang.Object

org.apache.tika.plugins.PluginComponentLoader

public class PluginComponentLoader
extends Object

Constructor Summary

Constructors

Constructor	Description
PluginComponentLoader()

Method Summary

Modifier and Type	Method	Description
static <T extends TikaExtension> T	buildExtension(TikaExtensionFactory<T> factory, ExtensionConfig config)	Builds an extension with the thread-context classloader set to the classloader of the plugin that supplied the factory.
static <T extends TikaExtension> Map<String,T>	loadInstances(org.pf4j.PluginManager pluginManager, Class<? extends TikaExtensionFactory<T>> factoryClass, com.fasterxml.jackson.databind.JsonNode configNode)	Load multiple named instances from config, grouped by type.
static <T extends TikaExtension> Optional<T>	loadSingleton(org.pf4j.PluginManager pluginManager, Class<? extends TikaExtensionFactory<T>> factoryClass, com.fasterxml.jackson.databind.JsonNode configNode)	Load a singleton component from config.
static <T extends TikaExtension> List<T>	loadUnnamedInstances(org.pf4j.PluginManager pluginManager, Class<? extends TikaExtensionFactory<T>> factoryClass, com.fasterxml.jackson.databind.JsonNode configNode)	Load multiple unnamed instances from config, keyed by type name.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

PluginComponentLoader

public PluginComponentLoader()

Method Details

buildExtension

public static <T extends TikaExtension> T buildExtension(TikaExtensionFactory<T> factory,
 ExtensionConfig config)
                                                  throws TikaConfigException,
IOException

Builds an extension with the thread-context classloader set to the classloader of the plugin that supplied the factory.

Client libraries a plugin bundles (Kafka, the AWS SDK, ZooKeeper) resolve classes named in their own configuration off the thread-context classloader and then cast the result to an interface resolved from their own classloader. Left at the host's classloader, that lookup either misses the plugin's lib/ entirely or - on a host that happens to carry the same library - finds a second copy of the class and the cast fails. Everything a plugin constructs must therefore see the plugin's classloader; pf4j does not set it.

Threads the library starts during construction inherit it, which is what keeps its own background threads resolving against the plugin. Factories that are not plugin-supplied are invoked without touching the context classloader.

Throws:

TikaConfigException

IOException

loadSingleton

public static <T extends TikaExtension> Optional<T> loadSingleton(org.pf4j.PluginManager pluginManager,
 Class<? extends TikaExtensionFactory<T>> factoryClass,
 com.fasterxml.jackson.databind.JsonNode configNode)
                                                           throws TikaConfigException,
IOException

Load a singleton component from config.

JSON structure: { "typeName": { config } }

Returns:

Optional containing the instance, or empty if configNode is null/empty

Throws:

TikaConfigException

IOException

loadInstances

public static <T extends TikaExtension>
Map<String,T> loadInstances(org.pf4j.PluginManager pluginManager,
 Class<? extends TikaExtensionFactory<T>> factoryClass,
 com.fasterxml.jackson.databind.JsonNode configNode)
                     throws TikaConfigException,
IOException

Load multiple named instances from config, grouped by type.

JSON structure:

 {
   "typeName": {
     "instanceId1": { config },
     "instanceId2": { config }
   },
   "typeName2": {
     "instanceId3": { config }
   }
 }
 

Throws:

TikaConfigException

IOException

loadUnnamedInstances

public static <T extends TikaExtension> List<T> loadUnnamedInstances(org.pf4j.PluginManager pluginManager,
 Class<? extends TikaExtensionFactory<T>> factoryClass,
 com.fasterxml.jackson.databind.JsonNode configNode)
                                                              throws TikaConfigException,
IOException

Load multiple unnamed instances from config, keyed by type name.

JSON structure: { "typeName": { config }, "typeName2": { config2 }, ... }

Use this for composite components like reporters where each type appears once and instances don't need individual names.

Returns:

List of instances in config order, empty list if configNode is null/empty

Throws:

TikaConfigException

IOException