Package org.apache.flink.table.types.extraction

Class ExtractionUtils

java.lang.Object

org.apache.flink.table.types.extraction.ExtractionUtils

@Internal
public final class ExtractionUtils
extends Object

Utilities for performing reflection tasks.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ExtractionUtils.AssigningConstructor	Result of the extraction in extractAssigningConstructor(Class, List).
static enum	ExtractionUtils.Autoboxing	Checks the relation between primitive and boxed types.

Method Summary

Modifier and Type	Method	Description
static Class<?>	classForName(String name, boolean initialize, ClassLoader classLoader)	Similar to Class.forName(String, boolean, ClassLoader) but resolves primitive names as well.
static List<Method>	collectMethods(Class<?> function, String methodName)	Collects methods of the given name.
static String	createMethodSignatureString(String methodName, Class<?>[] parameters, Class<?> returnType)	Creates a method signature string like int eval(Integer, String).
static ExtractionUtils.AssigningConstructor	extractAssigningConstructor(Class<?> clazz, List<Field> fields)	Checks whether the given constructor takes all of the given fields with matching (possibly primitive) type and name.
static Optional<Class<?>>	extractSimpleGeneric(Class<?> baseClass, Class<?> clazz, int pos)	A minimal version to extract a generic parameter from a given class.
static Class<?>	getClassFromType(Type type)	Gets the associated class type from a Type parameter.
static Field	getStructuredField(Class<?> clazz, String fieldName)	Returns the field of a structured type.
static Optional<Method>	getStructuredFieldGetter(Class<?> clazz, Field field)	Checks for a field getter of a structured type.
static Optional<Method>	getStructuredFieldSetter(Class<?> clazz, Field field)	Checks for a field setters of a structured type.
static boolean	hasInvokableConstructor(Class<?> clazz, Class<?>... classes)	Checks for an invokable constructor matching the given arguments.
static boolean	isAssignable(Class<?> cls, Class<?> toClass, ExtractionUtils.Autoboxing autoboxing)	Checks if one Class can be assigned to a variable of another Class.
static boolean	isInvokable(ExtractionUtils.Autoboxing autoboxing, Executable executable, Class<?>... classes)	Checks whether a method/constructor can be called with the given argument classes.
static boolean	isStructuredFieldDirectlyReadable(Field field)	Checks whether a field is directly readable without a getter.
static boolean	isStructuredFieldDirectlyWritable(Field field)	Checks whether a field is directly writable without a setter or constructor.
static Class<?>	primitiveToWrapper(Class<?> cls)	Converts the specified primitive Class object to its corresponding wrapper Class object.
static Type	resolveVariableWithClassContext(Type contextType, Type type)	Resolves a variable type while accepting a context for resolution.
static void	validateStructuredClass(Class<?> clazz)	Validates the characteristics of a class for a StructuredType such as accessibility.
static Class<?>	wrapperToPrimitive(Class<?> cls)	Converts the specified wrapper class to its corresponding primitive class.

Methods inherited from class java.lang.Object

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

Method Details

collectMethods

public static List<Method> collectMethods(Class<?> function,
 String methodName)

Collects methods of the given name.

isInvokable

public static boolean isInvokable(ExtractionUtils.Autoboxing autoboxing,
 Executable executable,
 Class<?>... classes)

Checks whether a method/constructor can be called with the given argument classes. This includes type widening and vararg. null is a wildcard.

E.g., (int.class, int.class) matches f(Object...), f(int, int), f(Integer, Object) and so forth.

createMethodSignatureString

public static String createMethodSignatureString(String methodName,
 Class<?>[] parameters,
 @Nullable
 Class<?> returnType)

Creates a method signature string like int eval(Integer, String).

validateStructuredClass

public static void validateStructuredClass(Class<?> clazz)

Validates the characteristics of a class for a StructuredType such as accessibility.

getStructuredField

public static Field getStructuredField(Class<?> clazz,
 String fieldName)

Returns the field of a structured type. The logic is as broad as possible to support both Java and Scala in different flavors.

getStructuredFieldGetter

public static Optional<Method> getStructuredFieldGetter(Class<?> clazz,
 Field field)

Checks for a field getter of a structured type. The logic is as broad as possible to support both Java and Scala in different flavors.

getStructuredFieldSetter

public static Optional<Method> getStructuredFieldSetter(Class<?> clazz,
 Field field)

Checks for a field setters of a structured type. The logic is as broad as possible to support both Java and Scala in different flavors.

hasInvokableConstructor

public static boolean hasInvokableConstructor(Class<?> clazz,
 Class<?>... classes)

Checks for an invokable constructor matching the given arguments.

See Also:

• isInvokable(Autoboxing, Executable, Class[])

isStructuredFieldDirectlyReadable

public static boolean isStructuredFieldDirectlyReadable(Field field)

Checks whether a field is directly readable without a getter.

isStructuredFieldDirectlyWritable

public static boolean isStructuredFieldDirectlyWritable(Field field)

Checks whether a field is directly writable without a setter or constructor.

extractSimpleGeneric

public static Optional<Class<?>> extractSimpleGeneric(Class<?> baseClass,
 Class<?> clazz,
 int pos)

A minimal version to extract a generic parameter from a given class.

This method should only be used for very specific use cases, in most cases DataTypeExtractor.extractFromGeneric(DataTypeFactory, Class, int, Type) should be more appropriate.

resolveVariableWithClassContext

public static Type resolveVariableWithClassContext(@Nullable
 Type contextType,
 Type type)

Resolves a variable type while accepting a context for resolution.

getClassFromType

public static Class<?> getClassFromType(Type type)

Gets the associated class type from a Type parameter.

extractAssigningConstructor

@Nullable
public static ExtractionUtils.AssigningConstructor extractAssigningConstructor(Class<?> clazz,
 List<Field> fields)

Checks whether the given constructor takes all of the given fields with matching (possibly primitive) type and name. An assigning constructor can define the order of fields.

isAssignable

public static boolean isAssignable(Class<?> cls,
 Class<?> toClass,
 ExtractionUtils.Autoboxing autoboxing)

Checks if one Class can be assigned to a variable of another Class.

Unlike the Class.isAssignableFrom(java.lang.Class) method, this method takes into account widenings of primitive classes and nulls.

Primitive widenings allow an int to be assigned to a long, float or double. This method returns the correct result for these cases.

Null may be assigned to any reference type. This method will return true if null is passed in and the toClass is non-primitive.

Specifically, this method tests whether the type represented by the specified Class parameter can be converted to the type represented by this Class object via an identity conversion widening primitive or widening reference conversion. See The Java Language Specification, sections 5.1.1, 5.1.2 and 5.1.4 for details.

Parameters:

cls - the Class to check, may be null

toClass - the Class to try to assign into, returns false if null

autoboxing - whether to use implicit autoboxing/unboxing between primitives and wrappers

autoboxing - checks whether null would end up in a primitive type and forbids it

Returns:

true if assignment possible

primitiveToWrapper

public static Class<?> primitiveToWrapper(Class<?> cls)

Converts the specified primitive Class object to its corresponding wrapper Class object.

NOTE: From v2.2, this method handles Void.TYPE, returning Void.TYPE.

Parameters:

cls - the class to convert, may be null

Returns:

the wrapper class for cls or cls if cls is not a primitive. null if null input.

Since:

2.1

wrapperToPrimitive

public static Class<?> wrapperToPrimitive(Class<?> cls)

Converts the specified wrapper class to its corresponding primitive class.

This method is the counter part of primitiveToWrapper(). If the passed in class is a wrapper class for a primitive type, this primitive type will be returned (e.g. Integer.TYPE for Integer.class). For other classes, or if the parameter is null, the return value is null.

Parameters:

cls - the class to convert, may be null

Returns:

the corresponding primitive type if cls is a wrapper class, null otherwise

Since:

2.4

See Also:

• primitiveToWrapper(Class)

classForName

public static Class<?> classForName(String name,
 boolean initialize,
 ClassLoader classLoader)
                             throws ClassNotFoundException

Similar to Class.forName(String, boolean, ClassLoader) but resolves primitive names as well.

Throws:

ClassNotFoundException