org.apache.avro.reflect

Class ReflectData

java.lang.Object

org.apache.avro.generic.GenericData

org.apache.avro.specific.SpecificData

org.apache.avro.reflect.ReflectData

Direct Known Subclasses:

ReflectData.AllowNull

public class ReflectData
extends SpecificData

Utilities to use existing Java classes and interfaces via reflection.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReflectData.AllowNull ReflectData implementation that permits null field values.

Nested classes/interfaces inherited from class org.apache.avro.specific.SpecificData

SpecificData.SchemaConstructable

Nested classes/interfaces inherited from class org.apache.avro.generic.GenericData

GenericData.Array<T>, GenericData.EnumSymbol, GenericData.Fixed, GenericData.InstanceSupplier, GenericData.Record, GenericData.StringType

Field Summary

Fields inherited from class org.apache.avro.specific.SpecificData

RESERVED_WORDS, stringableClasses

Fields inherited from class org.apache.avro.generic.GenericData

FAST_READER_PROP, STRING_PROP, STRING_TYPE_STRING

Constructor Summary

Constructors

Constructor and Description
ReflectData() For subclasses.
ReflectData(ClassLoader classLoader) Construct with a particular classloader.

Method Summary

Modifier and Type	Method and Description
ReflectData	addStringable(Class c) Cause a class to be treated as though it had an Stringable * annotation.
protected int	compare(Object o1, Object o2, Schema s, boolean equals) Comparison implementation.
DatumReader	createDatumReader(Schema schema) Returns a DatumReader for this kind of data.
DatumReader	createDatumReader(Schema writer, Schema reader) Returns a DatumReader for this kind of data.
DatumWriter	createDatumWriter(Schema schema) Returns a DatumWriter for this kind of data.
protected Schema	createFieldSchema(Field field, Map<String,Schema> names) Create a schema for a field.
Object	createFixed(Object old, Schema schema) Called to create an fixed value.
protected Schema	createSchema(Type type, Map<String,Schema> names) Create the schema for a Java type.
protected Object	createSchemaDefaultValue(Type type, Field field, Schema fieldSchema) Get default value for a schema field.
static ReflectData	get() Return the singleton instance.
protected Collection	getArrayAsCollection(Object datum) Called to access an array as a collection.
Class	getClass(Schema schema) Return the class that implements a schema, or null if none exists.
Object	getField(Object record, String name, int position) Called by GenericDatumReader.readRecord(java.lang.Object, org.apache.avro.Schema, org.apache.avro.io.ResolvingDecoder) to retrieve a record field value from a reused instance.
protected Object	getField(Object record, String name, int pos, Object state) Version of GenericData.getField(java.lang.Object, java.lang.String, int) that has state.
protected Object	getOrCreateDefaultValue(Type type) Get or create new value instance for a type.
protected Object	getOrCreateDefaultValue(Type type, Field field) Get or create new value instance for a field
Protocol	getProtocol(Class iface) Return the protocol for a Java interface.
protected Schema	getRecordSchema(Object record) Called to obtain the schema of a record.
protected Object	getRecordState(Object record, Schema schema) Produce state for repeated calls to GenericData.getField(Object,String,int,Object) and GenericData.setField(Object,String,int,Object,Object) on the same record.
protected boolean	isArray(Object datum) Returns true for arrays and false otherwise, with the following exceptions:
protected boolean	isBytes(Object datum) Called by the default implementation of GenericData.instanceOf(org.apache.avro.Schema, java.lang.Object).
protected boolean	isMap(Object datum) It returns false for non-string-maps because Avro writes out such maps as an array of records.
protected boolean	isRecord(Object datum) Called by the default implementation of GenericData.instanceOf(org.apache.avro.Schema, java.lang.Object).
protected boolean	isStringable(Class<?> c) True if a class should be serialized with toString().
static Schema	makeNullable(Schema schema) Create and return a union of the null schema and the provided schema.
Object	newRecord(Object old, Schema schema) Called to create new record instances.
ReflectData	setDefaultGeneratedValue(Type type, Object value) Set the default value for a type.
ReflectData	setDefaultsGenerated(boolean enabled) Enable or disable `default reflection`
void	setField(Object record, String name, int position, Object value) Called by GenericDatumReader.readRecord(java.lang.Object, org.apache.avro.Schema, org.apache.avro.io.ResolvingDecoder) to set a record fields value to a record instance.
protected void	setField(Object record, String name, int position, Object value, Object state) Version of GenericData.setField(java.lang.Object, java.lang.String, int, java.lang.Object) that has state.
boolean	useCustomCoders() Always false since custom coders are not available for ReflectData.
boolean	validate(Schema schema, Object datum) Returns true if a Java datum matches a schema.

Methods inherited from class org.apache.avro.specific.SpecificData

createEnum, createString, getClassName, getDecoder, getEncoder, getEnumSchema, getForClass, getForSchema, getNewRecordSupplier, getSchema, getSchemaName, isEnum, isStringType, newInstance, setCustomCoders, unmangle

Methods inherited from class org.apache.avro.generic.GenericData

addLogicalTypeConversion, compare, createFixed, deepCopy, getClassLoader, getConversionByClass, getConversionByClass, getConversionFor, getConversions, getDefaultValue, getFastReaderBuilder, getFixedSchema, getPrimitiveTypeCache, hashCode, hashCodeAdd, induce, instanceOf, isBoolean, isDouble, isFastReaderEnabled, isFixed, isFloat, isInteger, isLong, isString, newArray, newMap, resolveUnion, setFastReaderEnabled, setStringType, toString, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectData

public ReflectData()

For subclasses. Applications normally use get().

ReflectData

public ReflectData(ClassLoader classLoader)

Construct with a particular classloader.

Method Detail

useCustomCoders

public boolean useCustomCoders()

Always false since custom coders are not available for ReflectData.

Overrides:

useCustomCoders in class SpecificData

get

public static ReflectData get()

Return the singleton instance.

addStringable

public ReflectData addStringable(Class c)

Cause a class to be treated as though it had an Stringable * annotation.

setDefaultsGenerated

public ReflectData setDefaultsGenerated(boolean enabled)

Enable or disable `default reflection`

Parameters:

enabled - set to `true` to enable the feature. This feature is disabled by default

Returns:

The current instance

setDefaultGeneratedValue

public ReflectData setDefaultGeneratedValue(Type type,
                                            Object value)

Set the default value for a type. When encountering such type, we'll use this provided value instead of trying to create a new one.

NOTE: This method automatically enable feature `default reflection`.

Parameters:

type - The type

value - Its default value

Returns:

The current instance

getOrCreateDefaultValue

protected Object getOrCreateDefaultValue(Type type,
                                         Field field)

Get or create new value instance for a field

Parameters:

type - The current type

field - A child field

Returns:

The default field value

getOrCreateDefaultValue

protected Object getOrCreateDefaultValue(Type type)

Get or create new value instance for a type. New instances will be instantiated using no-arg constructors. The newly created one will be cached for later use.

Parameters:

type - The type

Returns:

The value

createDatumReader

public DatumReader createDatumReader(Schema schema)

Description copied from class: GenericData

Returns a DatumReader for this kind of data.

Overrides:

createDatumReader in class SpecificData

createDatumReader

public DatumReader createDatumReader(Schema writer,
                                     Schema reader)

Description copied from class: GenericData

Returns a DatumReader for this kind of data.

Overrides:

createDatumReader in class SpecificData

createDatumWriter

public DatumWriter createDatumWriter(Schema schema)

Description copied from class: GenericData

Returns a DatumWriter for this kind of data.

Overrides:

createDatumWriter in class SpecificData

setField

public void setField(Object record,
                     String name,
                     int position,
                     Object value)

Description copied from class: GenericData

Called by GenericDatumReader.readRecord(java.lang.Object, org.apache.avro.Schema, org.apache.avro.io.ResolvingDecoder) to set a record fields value to a record instance. The default implementation is for IndexedRecord.

Overrides:

setField in class GenericData

setField

protected void setField(Object record,
                        String name,
                        int position,
                        Object value,
                        Object state)

Description copied from class: GenericData

Version of GenericData.setField(java.lang.Object, java.lang.String, int, java.lang.Object) that has state.

Overrides:

setField in class GenericData

getField

public Object getField(Object record,
                       String name,
                       int position)

Description copied from class: GenericData

Called by GenericDatumReader.readRecord(java.lang.Object, org.apache.avro.Schema, org.apache.avro.io.ResolvingDecoder) to retrieve a record field value from a reused instance. The default implementation is for IndexedRecord.

Overrides:

getField in class GenericData

getField

protected Object getField(Object record,
                          String name,
                          int pos,
                          Object state)

Description copied from class: GenericData

Version of GenericData.getField(java.lang.Object, java.lang.String, int) that has state.

Overrides:

getField in class GenericData

isRecord

protected boolean isRecord(Object datum)

Description copied from class: GenericData

Called by the default implementation of GenericData.instanceOf(org.apache.avro.Schema, java.lang.Object).

Overrides:

isRecord in class GenericData

isArray

protected boolean isArray(Object datum)

Returns true for arrays and false otherwise, with the following exceptions:

• Returns true for non-string-keyed maps, which are written as an array of key/value pair records.

• Returns false for arrays of bytes, since those should be treated as byte data type instead.

Overrides:

isArray in class GenericData

getArrayAsCollection

protected Collection getArrayAsCollection(Object datum)

Description copied from class: GenericData

Called to access an array as a collection.

Overrides:

getArrayAsCollection in class GenericData

isBytes

protected boolean isBytes(Object datum)

Description copied from class: GenericData

Called by the default implementation of GenericData.instanceOf(org.apache.avro.Schema, java.lang.Object).

Overrides:

isBytes in class GenericData

getRecordSchema

protected Schema getRecordSchema(Object record)

Description copied from class: GenericData

Called to obtain the schema of a record. By default calls {GenericContainer#getSchema(). May be overridden for alternate record representations.

Overrides:

getRecordSchema in class GenericData

validate

public boolean validate(Schema schema,
                        Object datum)

Description copied from class: GenericData

Returns true if a Java datum matches a schema.

Overrides:

validate in class GenericData

isMap

protected boolean isMap(Object datum)

It returns false for non-string-maps because Avro writes out such maps as an array of records. Even their JSON representation is an array.

Overrides:

isMap in class GenericData

getClass

public Class getClass(Schema schema)

Description copied from class: SpecificData

Return the class that implements a schema, or null if none exists.

Overrides:

getClass in class SpecificData

createSchemaDefaultValue

protected Object createSchemaDefaultValue(Type type,
                                          Field field,
                                          Schema fieldSchema)

Get default value for a schema field. Derived classes can override this method to provide values based on object instantiation

Parameters:

type - Type

field - Field

fieldSchema - Schema of the field

Returns:

The default value

createSchema

protected Schema createSchema(Type type,
                              Map<String,Schema> names)

Description copied from class: SpecificData

Create the schema for a Java type.

Overrides:

createSchema in class SpecificData

isStringable

protected boolean isStringable(Class<?> c)

Description copied from class: SpecificData

True if a class should be serialized with toString().

Overrides:

isStringable in class SpecificData

makeNullable

public static Schema makeNullable(Schema schema)

Create and return a union of the null schema and the provided schema.

createFieldSchema

protected Schema createFieldSchema(Field field,
                                   Map<String,Schema> names)

Create a schema for a field.

getProtocol

public Protocol getProtocol(Class iface)

Return the protocol for a Java interface.

The correct name of the method parameters needs the -parameters java compiler argument. More info at https://openjdk.java.net/jeps/118

Overrides:

getProtocol in class SpecificData

compare

protected int compare(Object o1,
                      Object o2,
                      Schema s,
                      boolean equals)

Description copied from class: GenericData

Comparison implementation. When equals is true, only checks for equality, not for order.

Overrides:

compare in class SpecificData

getRecordState

protected Object getRecordState(Object record,
                                Schema schema)

Description copied from class: GenericData

Produce state for repeated calls to GenericData.getField(Object,String,int,Object) and GenericData.setField(Object,String,int,Object,Object) on the same record.

Overrides:

getRecordState in class GenericData

createFixed

public Object createFixed(Object old,
                          Schema schema)

Description copied from class: GenericData

Called to create an fixed value. May be overridden for alternate fixed representations. By default, returns GenericFixed.

Overrides:

createFixed in class SpecificData

newRecord

public Object newRecord(Object old,
                        Schema schema)

Description copied from class: GenericData

Called to create new record instances. Subclasses may override to use a different record implementation. The returned instance must conform to the schema provided. If the old object contains fields not present in the schema, they should either be removed from the old object, or it should create a new instance that conforms to the schema. By default, this returns a GenericData.Record.

Overrides:

newRecord in class SpecificData