com.datastax.driver.core

Class TypeCodec.AbstractMapCodec<K,V>

java.lang.Object

com.datastax.driver.core.TypeCodec<Map<K,V>>

com.datastax.driver.core.TypeCodec.AbstractMapCodec<K,V>

Enclosing class:

TypeCodec<T>

public abstract static class TypeCodec.AbstractMapCodec<K,V>
extends TypeCodec<Map<K,V>>

Base class for codecs mapping CQL maps to a Java Map.

Nested Class Summary

Nested classes/interfaces inherited from class com.datastax.driver.core.TypeCodec

TypeCodec.AbstractCollectionCodec<E,C extends Collection<E>>, TypeCodec.AbstractMapCodec<K,V>, TypeCodec.AbstractTupleCodec<T>, TypeCodec.AbstractUDTCodec<T>, TypeCodec.PrimitiveBooleanCodec, TypeCodec.PrimitiveByteCodec, TypeCodec.PrimitiveDoubleCodec, TypeCodec.PrimitiveFloatCodec, TypeCodec.PrimitiveIntCodec, TypeCodec.PrimitiveLongCodec, TypeCodec.PrimitiveShortCodec

Field Summary

Fields

Modifier and Type	Field and Description
protected TypeCodec<K>	keyCodec
protected TypeCodec<V>	valueCodec

Fields inherited from class com.datastax.driver.core.TypeCodec

cqlType, javaType

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMapCodec(TypeCodec<K> keyCodec, TypeCodec<V> valueCodec)

Method Summary

Modifier and Type	Method and Description
boolean	accepts(Object value) Return true if this codec is capable of serializing the given object.
Map<K,V>	deserialize(ByteBuffer bytes, ProtocolVersion protocolVersion) Deserialize the given ByteBuffer instance according to the CQL type handled by this codec.
String	format(Map<K,V> value) Format the given value as a valid CQL literal according to the CQL type handled by this codec.
protected abstract Map<K,V>	newInstance(int size) Return a new Map instance with the given estimated size.
Map<K,V>	parse(String value) Parse the given CQL literal into an instance of the Java type handled by this codec.
ByteBuffer	serialize(Map<K,V> value, ProtocolVersion protocolVersion) Serialize the given value according to the CQL type handled by this codec.

Methods inherited from class com.datastax.driver.core.TypeCodec

accepts, accepts, accepts, ascii, bigint, blob, cboolean, cdouble, cfloat, cint, counter, custom, date, decimal, duration, getCqlType, getJavaType, inet, list, map, set, smallInt, time, timestamp, timeUUID, tinyInt, toString, tuple, userType, uuid, varchar, varint

Methods inherited from class java.lang.Object

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

Field Detail

keyCodec

protected final TypeCodec<K> keyCodec

valueCodec

protected final TypeCodec<V> valueCodec

Constructor Detail

AbstractMapCodec

protected AbstractMapCodec(TypeCodec<K> keyCodec,
                           TypeCodec<V> valueCodec)

Method Detail

accepts

public boolean accepts(Object value)

Description copied from class: TypeCodec

Return true if this codec is capable of serializing the given object. Note that the object's Java type is inferred from the object's runtime (raw) type, contrary to TypeCodec.accepts(TypeToken) which is capable of handling generic types.

This method is intended mostly to be used by the QueryBuilder when no type information is available when the codec is used.

Implementation notes:

1. The default implementation is covariant with respect to the passed argument (through the usage of Class.isAssignableFrom(Class)) and it's strongly recommended not to modify this behavior. This means that, by default, a codec will accept any subtype of the Java type that it has been created for.
2. The base implementation provided here can only handle non-parameterized types; codecs handling parameterized types, such as collection types, must override this method and perform some sort of "manual" inspection of the actual type parameters.
3. Similarly, codecs that only accept a partial subset of all possible values must override this method and manually inspect the object to check if it complies or not with the codec's limitations.

Overrides:

accepts in class TypeCodec<Map<K,V>>

Parameters:

value - The Java type this codec should serialize from and deserialize to; cannot be null.

Returns:

true if the codec is capable of serializing the given javaType, and false otherwise.

parse

public Map<K,V> parse(String value)

Description copied from class: TypeCodec

Parse the given CQL literal into an instance of the Java type handled by this codec.

Implementors should take care of unquoting and unescaping the given CQL string where applicable. Null values and empty Strings should be accepted, as well as the string "NULL"; in most cases, implementations should interpret these inputs has equivalent to a null reference.

Implementing this method is not strictly mandatory: internally, the driver only uses it to parse the INITCOND when building the metadata of an aggregate function (and in most cases it will use a built-in codec, unless the INITCOND has a custom type).

Specified by:

parse in class TypeCodec<Map<K,V>>

Parameters:

value - The CQL string to parse, may be null or empty.

Returns:

An instance of T; may be null on a null input.

format

public String format(Map<K,V> value)

Description copied from class: TypeCodec

Format the given value as a valid CQL literal according to the CQL type handled by this codec.

Implementors should take care of quoting and escaping the resulting CQL literal where applicable. Null values should be accepted; in most cases, implementations should return the CQL keyword "NULL" for null inputs.

Implementing this method is not strictly mandatory. It is used:

1. in the query builder, when values are inlined in the query string (see BuiltStatement for a detailed explanation of when this happens);
2. in the QueryLogger, if parameter logging is enabled;
3. to format the INITCOND in AggregateMetadata.asCQLQuery(boolean);
4. in the toString() implementation of some objects (UDTValue, TupleValue, and the internal representation of a ROWS response), which may appear in driver logs.

If you choose not to implement this method, you should not throw an exception but instead return a constant string (for example "XxxCodec.format not implemented").

Specified by:

format in class TypeCodec<Map<K,V>>

Parameters:

value - An instance of T; may be null.

Returns:

CQL string

serialize

public ByteBuffer serialize(Map<K,V> value,
                            ProtocolVersion protocolVersion)

Description copied from class: TypeCodec

Serialize the given value according to the CQL type handled by this codec.

Implementation notes:

1. Null values should be gracefully handled and no exception should be raised; these should be considered as the equivalent of a NULL CQL value;
2. Codecs for CQL collection types should not permit null elements;
3. Codecs for CQL collection types should treat a null input as the equivalent of an empty collection.

Specified by:

serialize in class TypeCodec<Map<K,V>>

Parameters:

value - An instance of T; may be null.

protocolVersion - the protocol version to use when serializing bytes. In most cases, the proper value to provide for this argument is the value returned by ProtocolOptions.getProtocolVersion() (which is the protocol version in use by the driver).

Returns:

A ByteBuffer instance containing the serialized form of T

deserialize

public Map<K,V> deserialize(ByteBuffer bytes,
                            ProtocolVersion protocolVersion)

Description copied from class: TypeCodec

Deserialize the given ByteBuffer instance according to the CQL type handled by this codec.

Implementation notes:

1. Null or empty buffers should be gracefully handled and no exception should be raised; these should be considered as the equivalent of a NULL CQL value and, in most cases, should map to null or a default value for the corresponding Java type, if applicable;
2. Codecs for CQL collection types should clearly document whether they return immutable collections or not (note that the driver's default collection codecs return mutable collections);
3. Codecs for CQL collection types should avoid returning null; they should return empty collections instead (the driver's default collection codecs all comply with this rule).
4. The provided ByteBuffer should never be consumed by read operations that modify its current position; if necessary, ByteBuffer.duplicate() duplicate} it before consuming.

Specified by:

deserialize in class TypeCodec<Map<K,V>>

Parameters:

bytes - A ByteBuffer instance containing the serialized form of T; may be null or empty.

protocolVersion - the protocol version to use when serializing bytes. In most cases, the proper value to provide for this argument is the value returned by ProtocolOptions.getProtocolVersion() (which is the protocol version in use by the driver).

Returns:

An instance of T

newInstance

protected abstract Map<K,V> newInstance(int size)

Return a new Map instance with the given estimated size.

Parameters:

size - The estimated size of the collection to create.

Returns:

A new Map instance with the given estimated size.