Package com.sun.jna

Class Function

java.lang.Object

com.sun.jna.Pointer

com.sun.jna.Function

public class Function
extends Pointer

An abstraction for a native function pointer. An instance of Function represents a pointer to some native function. invoke(Class,Object[],Map) is the primary means to call the function.

Function call behavior may be modified by passing one of the following call flags:

• C_CONVENTION Use C calling convention (default)
• ALT_CONVENTION Use alternate calling convention (e.g. stdcall)
• THROW_LAST_ERROR Throw a LastErrorException if the native function sets the system error to a non-zero value (errno or GetLastError). Setting this flag will cause the system error to be cleared prior to native function invocation.

Author:

Sheng Liang, originator, Todd Fast, suitability modifications, Timothy Wall

See Also:

• Pointer

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	Function.PostCallRead	Any argument which implements this interface will have the Function.PostCallRead.read() method called immediately after function invocation.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	ALT_CONVENTION	First alternate convention (currently used only for w32 stdcall).
static final int	C_CONVENTION	Standard C calling convention.
(package private) final int	callFlags
(package private) final String	encoding
(package private) static final Integer	INTEGER_FALSE
(package private) static final Integer	INTEGER_TRUE
static final int	MAX_NARGS	Maximum number of arguments supported by a JNA function call.
(package private) static final String	OPTION_INVOKING_METHOD	For internal JNA use.
(package private) final Map<String,?>	options
static final int	THROW_LAST_ERROR	Whether to throw an exception if last error is non-zero after call.
static final int	USE_VARARGS	Mask for number of fixed args (max 255) for varargs calls.

Fields inherited from class com.sun.jna.Pointer

NULL, peer

Constructor Summary

Constructors

Constructor	Description
Function(NativeLibrary library, String functionName, int callFlags, String encoding)	Create a new Function that is linked with a native function that follows the given calling convention.
Function(Pointer functionAddress, int callFlags, String encoding)	Create a new Function that is linked with a native function that follows the given calling convention.

Method Summary

Modifier and Type	Method	Description
(package private) static Object[]	concatenateVarArgs(Object[] inArgs)	Concatenate varargs with normal args to obtain a simple argument array.
boolean	equals(Object o)	Two function pointers are equal if they share the same peer address and calling convention.
(package private) static int	fixedArgs(Method m)	Varargs are only supported on 1.5+.
int	getCallingConvention()
static Function	getFunction(Pointer p)	Obtain a Function representing a native function pointer.
static Function	getFunction(Pointer p, int callFlags)	Obtain a Function representing a native function pointer.
static Function	getFunction(Pointer p, int callFlags, String encoding)	Obtain a Function representing a native function pointer.
static Function	getFunction(String libraryName, String functionName)	Obtain a Function representing a native function that follows the standard "C" calling convention.
static Function	getFunction(String libraryName, String functionName, int callFlags)	Obtain a Function representing a native function.
static Function	getFunction(String libraryName, String functionName, int callFlags, String encoding)	Obtain a Function representing a native function.
String	getName()
int	hashCode()	Provide a unique hash code for Functions which are equivalent.
Object	invoke(Class<?> returnType, Object[] inArgs)	Invoke the native function with the given arguments, returning the native result as an Object.
Object	invoke(Class<?> returnType, Object[] inArgs, Map<String,?> options)	Invoke the native function with the given arguments, returning the native result as an Object.
void	invoke(Object[] args)	Call the native function being represented by this object
(package private) Object	invoke(Object[] args, Class<?> returnType, boolean allowObjects)
(package private) Object	invoke(Object[] args, Class<?> returnType, boolean allowObjects, int fixedArgs)
(package private) Object	invoke(Method invokingMethod, Class<?>[] paramTypes, Class<?> returnType, Object[] inArgs, Map<String,?> options)	Invoke the native function with the given arguments, returning the native result as an Object.
double	invokeDouble(Object[] args)	Convenience method for invoke(Double.class, args).
float	invokeFloat(Object[] args)	Convenience method for invoke(Float.class, args).
int	invokeInt(Object[] args)	Convenience method for invoke(Integer.class, args).
long	invokeLong(Object[] args)	Convenience method for invoke(Long.class, args).
Object	invokeObject(Object[] args)	Convenience method for invokeObject(Object.class, args).
Pointer	invokePointer(Object[] args)	Convenience method for invoke(Pointer.class, args).
String	invokeString(Object[] args, boolean wide)	Convenience method for invoke(String.class, args) or invoke(WString.class, args)
void	invokeVoid(Object[] args)	Convenience method for invoke(Void.class, args).
(package private) static boolean	isVarArgs(Method m)	Varargs are only supported on 1.5+.
String	toString()	Provide a human-readable representation of this object.
(package private) static Boolean	valueOf(boolean b)	Implementation of Boolean.valueOf for older VMs.

Methods inherited from class com.sun.jna.Pointer

clear, createConstant, createConstant, dump, getByte, getByteArray, getByteBuffer, getChar, getCharArray, getDouble, getDoubleArray, getFloat, getFloatArray, getInt, getIntArray, getLong, getLongArray, getNativeLong, getPointer, getPointerArray, getPointerArray, getShort, getShortArray, getString, getString, getStringArray, getStringArray, getStringArray, getStringArray, getValue, getWideString, getWideStringArray, getWideStringArray, indexOf, nativeValue, nativeValue, read, read, read, read, read, read, read, read, setByte, setChar, setDouble, setFloat, setInt, setLong, setMemory, setNativeLong, setPointer, setShort, setString, setString, setString, setValue, setWideString, share, share, write, write, write, write, write, write, write, write

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

MAX_NARGS

@Native
public static final int MAX_NARGS

Maximum number of arguments supported by a JNA function call.

See Also:

• Constant Field Values

C_CONVENTION

@Native
public static final int C_CONVENTION

Standard C calling convention.

See Also:

• Constant Field Values

ALT_CONVENTION

@Native
public static final int ALT_CONVENTION

First alternate convention (currently used only for w32 stdcall).

See Also:

• Constant Field Values

THROW_LAST_ERROR

@Native
public static final int THROW_LAST_ERROR

Whether to throw an exception if last error is non-zero after call.

See Also:

• Constant Field Values

USE_VARARGS

@Native
public static final int USE_VARARGS

Mask for number of fixed args (max 255) for varargs calls.

See Also:

• Constant Field Values

INTEGER_TRUE

static final Integer INTEGER_TRUE

INTEGER_FALSE

static final Integer INTEGER_FALSE

encoding

final String encoding

callFlags

final int callFlags

options

final Map<String,?> options

OPTION_INVOKING_METHOD

static final String OPTION_INVOKING_METHOD

For internal JNA use.

See Also:

• Constant Field Values

Constructor Details

Function

Function(NativeLibrary library,
 String functionName,
 int callFlags,
 String encoding)

Create a new Function that is linked with a native function that follows the given calling convention.

The allocated instance represents a pointer to the named native function from the supplied library, called with the given calling convention.

Parameters:

library - NativeLibrary in which to find the function

functionName - Name of the native function to be linked with

callFlags - Function call flags

encoding - Encoding for conversion between Java and native strings.

Throws:

UnsatisfiedLinkError - if the given function name is not found within the library.

Function

Function(Pointer functionAddress,
 int callFlags,
 String encoding)

Create a new Function that is linked with a native function that follows the given calling convention.

The allocated instance represents a pointer to the given function address, called with the given calling convention.

Parameters:

functionAddress - Address of the native function

callFlags - Function call flags

encoding - Encoding for conversion between Java and native strings.

Method Details

getFunction

public static Function getFunction(String libraryName,
 String functionName)

Obtain a Function representing a native function that follows the standard "C" calling convention.

The allocated instance represents a pointer to the named native function from the named library, called with the standard "C" calling convention.

Parameters:

libraryName - Library in which to find the native function

functionName - Name of the native function to be linked with

Throws:

UnsatisfiedLinkError - if the library is not found or the given function name is not found within the library.

getFunction

public static Function getFunction(String libraryName,
 String functionName,
 int callFlags)

Obtain a Function representing a native function.

The allocated instance represents a pointer to the named native function from the named library.

Parameters:

libraryName - Library in which to find the function

functionName - Name of the native function to be linked with

callFlags - Function call flags

Throws:

UnsatisfiedLinkError - if the library is not found or the given function name is not found within the library.

getFunction

public static Function getFunction(String libraryName,
 String functionName,
 int callFlags,
 String encoding)

Obtain a Function representing a native function.

The allocated instance represents a pointer to the named native function from the named library.

Parameters:

libraryName - Library in which to find the function

functionName - Name of the native function to be linked with

callFlags - Function call flags

encoding - Encoding to use for conversion between Java and native strings.

Throws:

UnsatisfiedLinkError - if the library is not found or the given function name is not found within the library.

getFunction

public static Function getFunction(Pointer p)

Obtain a Function representing a native function pointer. In general, this function should be used by dynamic languages; Java code should allow JNA to bind to a specific Callback interface instead by defining a return type or Structure field type.

The allocated instance represents a pointer to the native function pointer.

Parameters:

p - Native function pointer

getFunction

public static Function getFunction(Pointer p,
 int callFlags)

Obtain a Function representing a native function pointer. In general, this function should be used by dynamic languages; Java code should allow JNA to bind to a specific Callback interface instead by defining a return type or Structure field type.

The allocated instance represents a pointer to the native function pointer.

Parameters:

p - Native function pointer

callFlags - Function call flags

getFunction

public static Function getFunction(Pointer p,
 int callFlags,
 String encoding)

Obtain a Function representing a native function pointer. In general, this function should be used by dynamic languages; Java code should allow JNA to bind to a specific Callback interface instead by defining a return type or Structure field type.

The allocated instance represents a pointer to the native function pointer.

Parameters:

p - Native function pointer

callFlags - Function call flags

encoding - Encoding to use for conversion between Java and native strings.

getName

public String getName()

getCallingConvention

public int getCallingConvention()

invoke

public Object invoke(Class<?> returnType,
 Object[] inArgs)

Invoke the native function with the given arguments, returning the native result as an Object.

invoke

public Object invoke(Class<?> returnType,
 Object[] inArgs,
 Map<String,?> options)

Invoke the native function with the given arguments, returning the native result as an Object.

invoke

Object invoke(Method invokingMethod,
 Class<?>[] paramTypes,
 Class<?> returnType,
 Object[] inArgs,
 Map<String,?> options)

Invoke the native function with the given arguments, returning the native result as an Object. This method can be called if invoking method and parameter types are already at hand. When calling invoke(Class, Object[], Map), the method has to be in the options under key OPTION_INVOKING_METHOD.

invoke

Object invoke(Object[] args,
 Class<?> returnType,
 boolean allowObjects)

invoke

Object invoke(Object[] args,
 Class<?> returnType,
 boolean allowObjects,
 int fixedArgs)

invoke

public void invoke(Object[] args)

Call the native function being represented by this object

Parameters:

args - Arguments to pass to the native function

toString

public String toString()

Provide a human-readable representation of this object.

Overrides:

toString in class Pointer

invokeObject

public Object invokeObject(Object[] args)

Convenience method for invokeObject(Object.class, args).

invokePointer

public Pointer invokePointer(Object[] args)

Convenience method for invoke(Pointer.class, args).

invokeString

public String invokeString(Object[] args,
 boolean wide)

Convenience method for invoke(String.class, args) or invoke(WString.class, args)

Parameters:

args - Arguments passed to native function

wide - Whether the return value is of type wchar_t*; if false, the return value is of type char*.

invokeInt

public int invokeInt(Object[] args)

Convenience method for invoke(Integer.class, args).

invokeLong

public long invokeLong(Object[] args)

Convenience method for invoke(Long.class, args).

invokeFloat

public float invokeFloat(Object[] args)

Convenience method for invoke(Float.class, args).

invokeDouble

public double invokeDouble(Object[] args)

Convenience method for invoke(Double.class, args).

invokeVoid

public void invokeVoid(Object[] args)

Convenience method for invoke(Void.class, args).

equals

public boolean equals(Object o)

Two function pointers are equal if they share the same peer address and calling convention.

Overrides:

equals in class Pointer

hashCode

public int hashCode()

Provide a unique hash code for Functions which are equivalent.

Overrides:

hashCode in class Pointer

concatenateVarArgs

static Object[] concatenateVarArgs(Object[] inArgs)

Concatenate varargs with normal args to obtain a simple argument array.

isVarArgs

static boolean isVarArgs(Method m)

Varargs are only supported on 1.5+.

fixedArgs

static int fixedArgs(Method m)

Varargs are only supported on 1.5+.

valueOf

static Boolean valueOf(boolean b)

Implementation of Boolean.valueOf for older VMs.