Package org.apache.tika.config.loader

Class ComponentInstantiator

java.lang.Object

org.apache.tika.config.loader.ComponentInstantiator

public class ComponentInstantiator
extends Object

Utility class for instantiating Tika components from JSON configuration. Provides common logic for all component loaders to avoid code duplication.

Constructor Summary

Constructors

Constructor	Description
ComponentInstantiator()

Method Summary

Modifier and Type	Method	Description
static boolean	hasConfiguration(JsonConfig jsonConfig, com.fasterxml.jackson.databind.ObjectMapper objectMapper)	Checks if the JsonConfig contains actual configuration (non-empty JSON object with fields).
static <T> T	instantiate(Class<?> componentClass, com.fasterxml.jackson.databind.JsonNode configNode, com.fasterxml.jackson.databind.ObjectMapper objectMapper)	Instantiates a component from a JsonNode configuration.
static <T> T	instantiate(Class<?> componentClass, JsonConfig jsonConfig, ClassLoader classLoader, String componentTypeName, com.fasterxml.jackson.databind.ObjectMapper objectMapper)	Instantiates a component with JsonConfig constructor or falls back to zero-arg constructor.
static <T> T	instantiate(String typeName, com.fasterxml.jackson.databind.JsonNode configNode, com.fasterxml.jackson.databind.ObjectMapper objectMapper, ClassLoader classLoader)	Instantiates a component by resolving a friendly name or FQCN to a class.
static <T> T	instantiateComponent(String typeName, com.fasterxml.jackson.databind.JsonNode configNode, com.fasterxml.jackson.databind.ObjectMapper mapper, ClassLoader classLoader, Class<?> expectedType)	Instantiates a Tika component with full special-case handling.

Methods inherited from class java.lang.Object

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

Constructor Details

ComponentInstantiator

public ComponentInstantiator()

Method Details

instantiate

public static <T> T instantiate(Class<?> componentClass,
 JsonConfig jsonConfig,
 ClassLoader classLoader,
 String componentTypeName,
 com.fasterxml.jackson.databind.ObjectMapper objectMapper)
                         throws TikaConfigException

Instantiates a component with JsonConfig constructor or falls back to zero-arg constructor.

Instantiation strategy:

1. Try constructor with JsonConfig parameter
2. If not found and JSON config has actual configuration, throw error
3. Otherwise fall back to zero-arg constructor via ServiceLoader

Type Parameters:

T - the component type

Parameters:

componentClass - the component class to instantiate

jsonConfig - the JSON configuration for the component

classLoader - the class loader to use

componentTypeName - the component type name (e.g., "Detector", "Parser") for error messages

objectMapper - the Jackson ObjectMapper for parsing JSON

Returns:

the instantiated component

Throws:

TikaConfigException - if instantiation fails

instantiate

public static <T> T instantiate(Class<?> componentClass,
 com.fasterxml.jackson.databind.JsonNode configNode,
 com.fasterxml.jackson.databind.ObjectMapper objectMapper)
                         throws TikaConfigException

Instantiates a component from a JsonNode configuration.

Instantiation strategy:

1. Try constructor with JsonConfig parameter
2. Fall back to Jackson bean deserialization if config is provided
3. Fall back to zero-arg constructor if no config

Type Parameters:

T - the component type

Parameters:

componentClass - the component class to instantiate

configNode - the JSON configuration node (may be null or empty)

objectMapper - the Jackson ObjectMapper for deserialization

Returns:

the instantiated component

Throws:

TikaConfigException - if instantiation fails

instantiate

public static <T> T instantiate(String typeName,
 com.fasterxml.jackson.databind.JsonNode configNode,
 com.fasterxml.jackson.databind.ObjectMapper objectMapper,
 ClassLoader classLoader)
                         throws TikaConfigException

Instantiates a component by resolving a friendly name or FQCN to a class.

This is a convenience method that combines name resolution with instantiation.

Type Parameters:

T - the component type

Parameters:

typeName - the component type name (friendly name like "pdf-parser" or FQCN)

configNode - the JSON configuration node (may be null or empty)

objectMapper - the Jackson ObjectMapper for deserialization

classLoader - the class loader for name resolution

Returns:

the instantiated component

Throws:

TikaConfigException - if instantiation fails or type name is unknown

instantiateComponent

public static <T> T instantiateComponent(String typeName,
 com.fasterxml.jackson.databind.JsonNode configNode,
 com.fasterxml.jackson.databind.ObjectMapper mapper,
 ClassLoader classLoader,
 Class<?> expectedType)
                                  throws TikaConfigException

Instantiates a Tika component with full special-case handling.

This is the primary entry point for component instantiation from JSON configuration. Handles:

• Type resolution via ComponentNameResolver.resolveClass(java.lang.String, java.lang.ClassLoader)
• Type compatibility validation against expectedType
• Special cases: DefaultParser/DefaultDetector rejection, MimeTypes singleton
• _mime-include/_mime-exclude extraction and stripping
• Three-step instantiation: JsonConfig ctor → readerForUpdating → no-arg
• Initializable.initialize() callback
• Parser MIME filter wrapping

Parameters:

typeName - the component type name (friendly name or FQCN)

configNode - the JSON configuration node (may be null)

mapper - the ObjectMapper for deserialization

classLoader - the class loader for name resolution

expectedType - the expected interface/base type (for validation), or null to skip

Returns:

the instantiated component

Throws:

TikaConfigException - if instantiation fails

hasConfiguration

public static boolean hasConfiguration(JsonConfig jsonConfig,
 com.fasterxml.jackson.databind.ObjectMapper objectMapper)

Checks if the JsonConfig contains actual configuration (non-empty JSON object with fields).

Parameters:

jsonConfig - the JSON configuration

objectMapper - the Jackson ObjectMapper for parsing JSON

Returns:

true if there's meaningful configuration, false if empty or just "{}"