Package com.sun.jna

Class NativeLibrary

java.lang.Object

com.sun.jna.NativeLibrary

public class NativeLibrary
extends Object

Provides management of native library resources. One instance of this class corresponds to a single loaded native library. May also be used to map to the current process (see getProcess()).

Library Search Paths A search for a given library will scan the following locations:

1. jna.library.path User-customizable path
2. jna.platform.library.path Platform-specific paths
3. On OSX, ~/Library/Frameworks, /Library/Frameworks, and /System/Library/Frameworks will be searched for a framework with a name corresponding to that requested. Absolute paths to frameworks are also accepted, either ending at the framework name (sans ".framework") or the full path to the framework shared library (e.g. CoreServices.framework/CoreServices).
4. Context class loader classpath. Deployed native libraries may be installed on the classpath under ${os-prefix}/LIBRARY_FILENAME, where ${os-prefix} is the OS/Arch prefix returned by Platform.getNativeLibraryResourcePrefix(). If bundled in a jar file, the resource will be extracted to jna.tmpdir for loading, and later removed (but only if jna.nounpack is false or not set).

You may set the system property jna.debug_load=true to make JNA print the steps of its library search to the console.

Author:

Wayne Meissner, split library loading from Function.java, twall

Field Summary

Fields

Modifier and Type	Field	Description
(package private) int	callFlags
(package private) Map<String,?>	options

Method Summary

Modifier and Type	Method	Description
static void	addSearchPath(String libraryName, String path)	Add a path to search for the specified library, ahead of any system paths.
void	dispose()	Close the native library we're mapped to.
(package private) static void	disposeAll()	Close all open native libraries.
protected void	finalize()	Close the library when it is no longer referenced.
File	getFile()	Returns the file on disk corresponding to this NativeLibrary instance.
Function	getFunction(String functionName)	Create a new Function that is linked with a native function that follows the NativeLibrary's calling convention.
Function	getFunction(String functionName, int callFlags)	Create a new Function that is linked with a native function that follows a given calling flags.
Function	getFunction(String functionName, int callFlags, String encoding)	Create a new Function that is linked with a native function that follows a given calling flags.
(package private) Function	getFunction(String name, Method method)	Create a new Function that is linked with a native function that follows the NativeLibrary's calling convention.
Pointer	getGlobalVariableAddress(String symbolName)	Look up the given global variable within this library.
static NativeLibrary	getInstance(String libraryName)	Returns an instance of NativeLibrary for the specified name.
static NativeLibrary	getInstance(String libraryName, ClassLoader classLoader)	Returns an instance of NativeLibrary for the specified name.
static NativeLibrary	getInstance(String libraryName, Map<String,?> libraryOptions)	Returns an instance of NativeLibrary for the specified name.
String	getName()	Returns the simple name of this library.
Map<String,?>	getOptions()
static NativeLibrary	getProcess()	Returns an instance of NativeLibrary which refers to the current process.
static NativeLibrary	getProcess(Map<String,?> options)	Returns an instance of NativeLibrary which refers to the current process.
(package private) long	getSymbolAddress(String name)	Used by the Function class to locate a symbol
(package private) static String	mapSharedLibraryName(String libName)	Similar to System.mapLibraryName(java.lang.String), except that it maps to standard shared library formats rather than specifically JNI formats.
(package private) static String[]	matchFramework(String libraryName)	Look for a matching framework (OSX)
(package private) static String	matchLibrary(String libName, Collection<String> searchPath)	matchLibrary() is very Linux specific.
(package private) static double	parseVersion(String ver)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

callFlags

final int callFlags

options

final Map<String,?> options

Method Detail

matchFramework

static String[] matchFramework(String libraryName)

Look for a matching framework (OSX)

getInstance

public static final NativeLibrary getInstance(String libraryName)

Returns an instance of NativeLibrary for the specified name. The library is loaded if not already loaded. If already loaded, the existing instance is returned.

More than one name may map to the same NativeLibrary instance; only a single instance will be provided for any given unique file path.

Parameters:

libraryName - The library name to load. This can be short form (e.g. "c"), an explicit version (e.g. "libc.so.6"), or the full path to the library (e.g. "/lib/libc.so.6").

getInstance

public static final NativeLibrary getInstance(String libraryName,
                                              ClassLoader classLoader)

Returns an instance of NativeLibrary for the specified name. The library is loaded if not already loaded. If already loaded, the existing instance is returned.

More than one name may map to the same NativeLibrary instance; only a single instance will be provided for any given unique file path.

Parameters:

libraryName - The library name to load. This can be short form (e.g. "c"), an explicit version (e.g. "libc.so.6"), or the full path to the library (e.g. "/lib/libc.so.6").

classLoader - The class loader to use to load the native library. This only affects library loading when the native library is included somewhere in the classpath, either bundled in a jar file or as a plain file within the classpath.

getInstance

public static final NativeLibrary getInstance(String libraryName,
                                              Map<String,?> libraryOptions)

Returns an instance of NativeLibrary for the specified name. The library is loaded if not already loaded. If already loaded, the existing instance is returned.

More than one name may map to the same NativeLibrary instance; only a single instance will be provided for any given unique file path.

Parameters:

libraryName - The library name to load. This can be short form (e.g. "c"), an explicit version (e.g. "libc.so.6" or "QuickTime.framework/Versions/Current/QuickTime"), or the full (absolute) path to the library (e.g. "/lib/libc.so.6").

libraryOptions - Native library options for the given library (see Library).

getProcess

public static final NativeLibrary getProcess()

Returns an instance of NativeLibrary which refers to the current process. This is useful for accessing functions which were already mapped by some other mechanism, without having to reference or even know the exact name of the native library.

getProcess

public static final NativeLibrary getProcess(Map<String,?> options)

Returns an instance of NativeLibrary which refers to the current process. This is useful for accessing functions which were already mapped by some other mechanism, without having to reference or even know the exact name of the native library.

addSearchPath

public static final void addSearchPath(String libraryName,
                                       String path)

Add a path to search for the specified library, ahead of any system paths. This is similar to setting jna.library.path, but only extends the search path for a single library.

Parameters:

libraryName - The name of the library to use the path for

path - The path to use when trying to load the library

getFunction

public Function getFunction(String functionName)

Create a new Function that is linked with a native function that follows the NativeLibrary's calling convention.

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

Parameters:

functionName - Name of the native function to be linked with

Throws:

UnsatisfiedLinkError - if the function is not found

getFunction

Function getFunction(String name,
                     Method method)

Create a new Function that is linked with a native function that follows the NativeLibrary's calling convention.

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

Parameters:

name - Name of the native function to be linked with. Uses a function mapper option if one was provided to transform the name.

method - Method to which the native function is to be mapped

Throws:

UnsatisfiedLinkError - if the function is not found

getFunction

public Function getFunction(String functionName,
                            int callFlags)

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

Parameters:

functionName - Name of the native function to be linked with

callFlags - Flags affecting the function invocation

Throws:

UnsatisfiedLinkError - if the function is not found

getFunction

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

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

Parameters:

functionName - Name of the native function to be linked with

callFlags - Flags affecting the function invocation

encoding - Encoding to use to convert between Java and native strings.

Throws:

UnsatisfiedLinkError - if the function is not found

getOptions

public Map<String,?> getOptions()

Returns:

this native library instance's options.

getGlobalVariableAddress

public Pointer getGlobalVariableAddress(String symbolName)

Look up the given global variable within this library.

Parameters:

symbolName -

Returns:

Pointer representing the global variable address

Throws:

UnsatisfiedLinkError - if the symbol is not found

getSymbolAddress

long getSymbolAddress(String name)

Used by the Function class to locate a symbol

Throws:

UnsatisfiedLinkError - if the symbol can't be found

toString

public String toString()

Overrides:

toString in class Object

getName

public String getName()

Returns the simple name of this library.

getFile

public File getFile()

Returns the file on disk corresponding to this NativeLibrary instance. If this NativeLibrary represents the current process, this function will return null.

finalize

protected void finalize()

Close the library when it is no longer referenced.

Overrides:

finalize in class Object

disposeAll

static void disposeAll()

Close all open native libraries.

dispose

public void dispose()

Close the native library we're mapped to.

mapSharedLibraryName

static String mapSharedLibraryName(String libName)

Similar to System.mapLibraryName(java.lang.String), except that it maps to standard shared library formats rather than specifically JNI formats.

Parameters:

libName - base (undecorated) name of library

matchLibrary

static String matchLibrary(String libName,
                           Collection<String> searchPath)

matchLibrary() is very Linux specific. It is here to deal with the case where /usr/lib/libc.so does not exist, or it is not a valid symlink to a versioned file (e.g. /lib/libc.so.6).

parseVersion

static double parseVersion(String ver)