com.alibaba.fastjson2

Class TypeReference<T>

java.lang.Object

com.alibaba.fastjson2.TypeReference<T>

Type Parameters:

T - the type refered to

public abstract class TypeReference<T>
extends java.lang.Object

Represents a generic type T.

Java doesn't yet provide a way to represent generic types, so this class does. Forces clients to create a subclass of this class which enables retrieval the type information even at runtime.

This syntax cannot be used to create type literals that have wildcard parameters, such as Class<T> or List<? extends CharSequence>.

For example, to create a type literal for List<String>, you can create an empty anonymous inner class:

 TypeReference<List<String>> typeReference = new TypeReference<List<String>>(){};
 

For example, use it quickly:

 String text = "{\"id\":1,\"name\":\"kraity\"}";
 User user = new TypeReference<User>(){}.parseObject(text);
 

Since:

2.0.2

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Class<? super T>	rawType
protected java.lang.reflect.Type	type

Constructor Summary

Constructors

Modifier	Constructor and Description
	TypeReference() Constructs a new type literal.
	TypeReference(java.lang.reflect.Type... actualTypeArguments) Constructs a new type literal with the specified actual type arguments.
private	TypeReference(java.lang.reflect.Type type) Constructs a new type literal with the specified type.

Method Summary

Modifier and Type	Method and Description
static java.lang.reflect.Type	arrayType(java.lang.Class<?> elementType) Creates an array type with the specified element type.
private static java.lang.reflect.Type	canonicalize(java.lang.Class<?> thisClass, java.lang.reflect.ParameterizedType type, java.lang.reflect.Type[] actualTypeArguments, int actualIndex) Canonicalize the type.
static java.lang.reflect.Type	collectionType(java.lang.Class<? extends java.util.Collection> collectionClass, java.lang.Class<?> elementClass) Creates a collection type with the specified collection class and element class.
static TypeReference<?>	get(java.lang.reflect.Type type) Gets a type reference for the specified type.
java.lang.Class<? super T>	getRawType() Gets the raw type.
java.lang.reflect.Type	getType() Gets the type literal.
static java.lang.reflect.Type	mapType(java.lang.Class<?> keyClass, java.lang.reflect.Type valueType) Creates a map type with the specified key class and value type.
static java.lang.reflect.Type	mapType(java.lang.Class<? extends java.util.Map> mapClass, java.lang.Class<?> keyClass, java.lang.Class<?> valueClass) Creates a map type with the specified map class, key class and value class.
static java.lang.reflect.Type	of(java.lang.reflect.Type... types) Creates a multi-type from the specified types.
static java.lang.reflect.Type	parametricType(java.lang.Class<?> parametrized, java.lang.Class<?>... parameterClasses) Creates a parameterized type with the specified parametrized class and parameter classes.
static java.lang.reflect.Type	parametricType(java.lang.Class<?> parametrized, java.lang.reflect.Type... parameterTypes) Creates a parameterized type with the specified parametrized class and parameter types.
java.util.List<T>	parseArray(byte[] utf8Bytes, JSONReader.Feature... features) See JSON.parseArray(byte[], Type, JSONReader.Feature...) for details
java.util.List<T>	parseArray(java.lang.String text, JSONReader.Feature... features) See JSON.parseArray(String, JSONReader.Feature...) for details
T	parseObject(byte[] utf8Bytes) See JSON.parseObject(byte[], Type) for details
T	parseObject(java.lang.String text) See JSON.parseObject(String, Type) for details
T	to(JSONArray array) See JSONArray.to(Type) for details
T	to(JSONObject object, JSONReader.Feature... features) See JSONObject.to(Type, JSONReader.Feature...) for details
T	toJavaObject(JSONArray array) Deprecated. since 2.0.4, please use to(JSONArray)
T	toJavaObject(JSONObject object, JSONReader.Feature... features) Deprecated. since 2.0.4, please use to(JSONObject, JSONReader.Feature...)

Methods inherited from class java.lang.Object

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

Field Detail

type

protected final java.lang.reflect.Type type

rawType

protected final java.lang.Class<? super T> rawType

Constructor Detail

TypeReference

public TypeReference()

Constructs a new type literal. Derives represented class from type parameter.

Clients create an empty anonymous subclass. Doing so embeds the type parameter in the anonymous class's type hierarchy, so we can reconstitute it at runtime despite erasure.

TypeReference

private TypeReference(java.lang.reflect.Type type)

Constructs a new type literal with the specified type.

Parameters:

type - specify the Type to be converted

Throws:

java.lang.NullPointerException - If the Type is null

TypeReference

public TypeReference(java.lang.reflect.Type... actualTypeArguments)

Constructs a new type literal with the specified actual type arguments.

For example:

 Class<T> klass = ...;
 TypeReference<Response<T>> ref = new TypeReference<Response<T>>(new Type[]{klass}){};
 

Parameters:

actualTypeArguments - an array of Type objects representing the actual type arguments to this type

Throws:

java.lang.NullPointerException - If the actualTypeArguments is null or empty

Since:

2.0.2

Method Detail

getType

public final java.lang.reflect.Type getType()

Gets the type literal.

Returns:

the Type

getRawType

public final java.lang.Class<? super T> getRawType()

Gets the raw type.

Returns:

the raw Class

parseObject

public T parseObject(java.lang.String text)

See JSON.parseObject(String, Type) for details

 String text = "{\"id\":1,\"name\":\"kraity\"}";
 User user = new TypeReference<User>(){}.parseObject(text);
 

Parameters:

text - the JSON String to be parsed

Since:

2.0.2

parseObject

public T parseObject(byte[] utf8Bytes)

See JSON.parseObject(byte[], Type) for details

 String utf8Bytes = "{\"id\":1,\"name\":\"kraity\"}".getBytes(StandardCharsets.UTF_8);
 User user = new TypeReference<User>(){}.parseObject(utf8Bytes);
 

Parameters:

utf8Bytes - UTF8 encoded JSON byte array to parse

Since:

2.0.3

parseArray

public java.util.List<T> parseArray(java.lang.String text,
                                    JSONReader.Feature... features)

See JSON.parseArray(String, JSONReader.Feature...) for details

 String text = "[{\"id\":1,\"name\":\"kraity\"}]";
 List<User> users = new TypeReference<User>(){}.parseArray(text);
 

Parameters:

text - the JSON String to be parsed

features - features to be enabled in parsing

Since:

2.0.2

parseArray

public java.util.List<T> parseArray(byte[] utf8Bytes,
                                    JSONReader.Feature... features)

See JSON.parseArray(byte[], Type, JSONReader.Feature...) for details

 String utf8Bytes = "[{\"id\":1,\"name\":\"kraity\"}]".getBytes(StandardCharsets.UTF_8);
 List<User> users = new TypeReference<User>(){}.parseArray(utf8Bytes);
 

Parameters:

utf8Bytes - UTF8 encoded JSON byte array to parse

features - features to be enabled in parsing

Since:

2.0.3

to

public T to(JSONArray array)

See JSONArray.to(Type) for details

 JSONArray array = ...
 List<User> users = new TypeReference<ArrayList<User>>(){}.to(array);
 

Parameters:

array - specify the JSONArray to convert

Since:

2.0.4

to

public T to(JSONObject object,
            JSONReader.Feature... features)

See JSONObject.to(Type, JSONReader.Feature...) for details

 JSONObject object = ...
 Map<String, User> users = new TypeReference<HashMap<String, User>>(){}.to(object);
 

Parameters:

object - specify the JSONObject to convert

features - features to be enabled in parsing

Since:

2.0.4

toJavaObject

@Deprecated
public T toJavaObject(JSONArray array)

Deprecated. since 2.0.4, please use to(JSONArray)

See JSONArray.toJavaObject(Type) for details

Parameters:

array - specify the JSONArray to convert

toJavaObject

@Deprecated
public T toJavaObject(JSONObject object,
                                  JSONReader.Feature... features)

Deprecated. since 2.0.4, please use to(JSONObject, JSONReader.Feature...)

See JSONObject.to(Type, JSONReader.Feature...) for details

Parameters:

object - specify the JSONObject to convert

features - features to be enabled in parsing

get

public static TypeReference<?> get(java.lang.reflect.Type type)

Gets a type reference for the specified type.

Parameters:

type - specify the Type to be converted

Returns:

the type reference

canonicalize

private static java.lang.reflect.Type canonicalize(java.lang.Class<?> thisClass,
                                                   java.lang.reflect.ParameterizedType type,
                                                   java.lang.reflect.Type[] actualTypeArguments,
                                                   int actualIndex)

Canonicalize the type.

Parameters:

thisClass - this class

type - the parameterizedType

actualTypeArguments - an array of Type objects representing the actual type arguments to this type

actualIndex - the actual index

Returns:

the canonicalized type

Since:

2.0.3

of

public static java.lang.reflect.Type of(java.lang.reflect.Type... types)

Creates a multi-type from the specified types.

Parameters:

types - the types

Returns:

the multi-type

collectionType

public static java.lang.reflect.Type collectionType(java.lang.Class<? extends java.util.Collection> collectionClass,
                                                    java.lang.Class<?> elementClass)

Creates a collection type with the specified collection class and element class.

Parameters:

collectionClass - the collection class

elementClass - the element class

Returns:

the parameterized type

arrayType

public static java.lang.reflect.Type arrayType(java.lang.Class<?> elementType)

Creates an array type with the specified element type.

Parameters:

elementType - the element type

Returns:

the generic array type

mapType

public static java.lang.reflect.Type mapType(java.lang.Class<? extends java.util.Map> mapClass,
                                             java.lang.Class<?> keyClass,
                                             java.lang.Class<?> valueClass)

Creates a map type with the specified map class, key class and value class.

Parameters:

mapClass - the map class

keyClass - the key class

valueClass - the value class

Returns:

the parameterized type

mapType

public static java.lang.reflect.Type mapType(java.lang.Class<?> keyClass,
                                             java.lang.reflect.Type valueType)

Creates a map type with the specified key class and value type.

Parameters:

keyClass - the key class

valueType - the value type

Returns:

the parameterized type

parametricType

public static java.lang.reflect.Type parametricType(java.lang.Class<?> parametrized,
                                                    java.lang.Class<?>... parameterClasses)

Creates a parameterized type with the specified parametrized class and parameter classes.

Parameters:

parametrized - the parametrized class

parameterClasses - the parameter classes

Returns:

the parameterized type

parametricType

public static java.lang.reflect.Type parametricType(java.lang.Class<?> parametrized,
                                                    java.lang.reflect.Type... parameterTypes)

Creates a parameterized type with the specified parametrized class and parameter types.

Parameters:

parametrized - the parametrized class

parameterTypes - the parameter types

Returns:

the parameterized type