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## com.sun.jna
Class Native

    java.lang.Object
      com.sun.jna.Native

    public final class Native

extends Object

Provides generation of invocation plumbing for a defined native library interface. Also provides various utilities for native operations.

`getTypeMapper(java.lang.Class)` and `getStructureAlignment(java.lang.Class)` are provided to avoid having to explicitly pass these parameters to `Structure`s, which would require every `Structure` which requires custom mapping or alignment to define a constructor and pass parameters to the superclass. To avoid lots of boilerplate, the base `Structure` constructor figures out these properties based on its enclosing interface.

## Library Loading

When JNA classes are loaded, the native shared library (jnidispatch) is loaded as well. An attempt is made to load it from the system library path using `System.loadLibrary(java.lang.String)`. If not found, the appropriate library will be extracted from the class path into a temporary directory and loaded from there. If your system has additional security constraints regarding execution or load of files (SELinux, for example), you should probably install the native library in an accessible location and configure your system accordingly, rather than relying on JNA to extract the library from its own jar file.

Author:
  Todd Fast, todd.fast@sun.com, twall@users.sf.net
See Also:
  `Native.DeleteNativeLibrary`

Nested Class Summary
`static class` | `Native.DeleteNativeLibrary` For internal use only.
`static interface` | `Native.ffi_callback`

Field Summary
`static int` | `LONG_SIZE` Size of a native `long` type, in bytes.
`static int` | `POINTER_SIZE` The size of a native pointer (`void*`) on the current platform, in bytes.
`static int` | `SIZE_T_SIZE` Size of a native `size_t` type, in bytes.
`static int` | `WCHAR_SIZE` Size of a native `wchar_t` type, in bytes.

Method Summary
`static void` | `ffi_call(long cif, long fptr, long resp, long args)`
`static void` | `ffi_free_closure(long closure)`
`static long` | `ffi_prep_cif(int abi, int nargs, long ffi_return_type, long ffi_types)`
`static long` | `ffi_prep_closure(long cif, Native.ffi_callback cb)`
`(package private) static Class` | `findEnclosingLibraryClass(Class cls)` Find the library interface corresponding to the given class.
`(package private) static byte[]` | `getBytes(String s)` Return a byte array corresponding to the given String.
`(package private) static byte[]` | `getBytes(String s, String encoding)` Return a byte array corresponding to the given String, using the given encoding.
`static Callback.UncaughtExceptionHandler` | `getCallbackExceptionHandler()` Returns the current handler for callback uncaught exceptions.
`(package private) static Class` | `getCallingClass()`
`static long` | `getComponentID(Component c)` Utility method to get the native window ID for a heavyweight Java `Component` as a `long` value.
`static Pointer` | `getComponentPointer(Component c)` Utility method to get the native window pointer for a heavyweight Java `Component` as a `Pointer` value.
`static Pointer` | `getDirectBufferPointer(Buffer b)` Convert a direct `Buffer` into a `Pointer`.
`static int` | `getLastError()` Retrieve the last error set by the OS.
`static Map` | `getLibraryOptions(Class type)` Return the preferred native library configuration options for the given class.
`(package private) static Class` | `getNativeClass(Class cls)`
`(package private) static String` | `getNativeLibraryResourcePath(int osType, String arch, String name)`
`static int` | `getNativeSize(Class cls)` Returns the native size for a given Java class.
`static int` | `getNativeSize(Class type, Object value)` Returns the native size of the given class, in bytes.
`static boolean` | `getPreserveLastError()` Deprecated. The preferred method of obtaining the last error result is to declare your mapped method to throw `LastErrorException` instead.
`static int` | `getStructureAlignment(Class cls)` Return the preferred structure alignment for the given native interface.
`static TypeMapper` | `getTypeMapper(Class cls)` Return the preferred `TypeMapper` for the given native interface.
`static String` | `getWebStartLibraryPath(String libName)` If running web start, determine the location of a given native library.
`static long` | `getWindowID(Window w)` Utility method to get the native window ID for a Java `Window` as a `long` value.
`static Pointer` | `getWindowPointer(Window w)` Utility method to get the native window pointer for a Java `Window` as a `Pointer` value.
`(package private) static int` | `initialize_ffi_type(long type_info)` Returns the size (calculated by libffi) of the given type.
`static boolean` | `isProtected()` Returns whether protection is enabled.
`static boolean` | `isSupportedNativeType(Class cls)` Indicate whether the given class is supported as a native argument type.
`static Object` | `loadLibrary(Class interfaceClass)` Map a library interface to the current process, providing the explicit interface class.
`static Object` | `loadLibrary(Class interfaceClass, Map options)` Map a library interface to the current process, providing the explicit interface class.
`static Object` | `loadLibrary(String name, Class interfaceClass)` Map a library interface to the given shared library, providing the explicit interface class.
`static Object` | `loadLibrary(String name, Class interfaceClass, Map options)` Load a library interface from the given shared library, providing the explicit interface class and a map of options for the library.
`static void` | `main(String[] args)` Prints JNA library details to the console.
`static void` | `register(Class cls, NativeLibrary lib)` When called from a class static initializer, maps all native methods found within that class to native libraries via the JNA raw calling interface.
`static void` | `register(NativeLibrary lib)` When called from a class static initializer, maps all native methods found within that class to native libraries via the JNA raw calling interface.
`static void` | `register(String libName)` When called from a class static initializer, maps all native methods found within that class to native libraries via the JNA raw calling interface.
`(package private) static String` | `replace(String s1, String s2, String str)`
`static void` | `setCallbackExceptionHandler(Callback.UncaughtExceptionHandler eh)` Set the default handler invoked when a callback throws an uncaught exception.
`static void` | `setLastError(int code)` Set the OS last error code.
`static void` | `setPreserveLastError(boolean enable)` Deprecated. The preferred method of obtaining the last error result is to declare your mapped method to throw `LastErrorException` instead.
`static void` | `setProtected(boolean enable)` Set whether native memory accesses are protected from invalid accesses.
`static Library` | `synchronizedLibrary(Library library)` Returns a synchronized (thread-safe) library backed by the specified library.
`static byte[]` | `toByteArray(String s)` Obtain a NUL-terminated byte buffer equivalent to the given String, using `jna.encoding` or the default platform encoding if that property is not set.
`static byte[]` | `toByteArray(String s, String encoding)` Obtain a NUL-terminated byte buffer equivalent to the given String, using the given encoding.
`static char[]` | `toCharArray(String s)` Obtain a NUL-terminated wide character buffer equivalent to the given String.
`static String` | `toString(byte[] buf)` Obtain a Java String from the given native byte array.
`static String` | `toString(byte[] buf, String encoding)` Obtain a Java String from the given native byte array, using the given encoding.
`static String` | `toString(char[] buf)` Obtain a Java String from the given native wchar_t array.
`static void` | `unregister()` Remove all native mappings for the calling class.
`static void` | `unregister(Class cls)` Remove all native mappings for the given class.
`(package private) static void` | `updateLastError(int e)` Update the last error value (called from native code).

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### POINTER_SIZE

    public static final int POINTER_SIZE

  The size of a native pointer (`void*`) on the current platform, in bytes.

### LONG_SIZE

    public static final int LONG_SIZE

  Size of a native `long` type, in bytes.

### WCHAR_SIZE

    public static final int WCHAR_SIZE

  Size of a native `wchar_t` type, in bytes.

### SIZE_T_SIZE

    public static final int SIZE_T_SIZE

  Size of a native `size_t` type, in bytes.

Method Detail

### setProtected

    public static void setProtected(boolean enable)

  Set whether native memory accesses are protected from invalid accesses. This should only be set true when testing or debugging, and should not be considered reliable or robust for applications where JNA native calls are occurring on multiple threads. Protected mode will be automatically set if the system property `jna.protected` has a value of "true" when the JNA library is first loaded.

  If not supported by the underlying platform, this setting will have no effect.

  NOTE: On platforms which support signals (non-Windows), JNA uses signals to trap errors. This may interfere with the JVM's own use of signals. When protected mode is enabled, you should make use of the jsig library, if available (see Signal Chaining). In short, set the environment variable `LD_PRELOAD` to the path to `libjsig.so` in your JRE lib directory (usually ${java.home}/lib/${os.arch}/libjsig.so) before launching your Java application.

### isProtected

    public static boolean isProtected()

  Returns whether protection is enabled. Check the result of this method after calling `setProtected(true)` to determine if this platform supports protecting memory accesses.

### setPreserveLastError

    public static void setPreserveLastError(boolean enable)

  Deprecated. The preferred method of obtaining the last error result is to declare your mapped method to throw `LastErrorException` instead.

  Set whether the system last error result is captured after every native invocation. Defaults to `true` (`false` for direct-mapped calls).

### getPreserveLastError

    public static boolean getPreserveLastError()

  Deprecated. The preferred method of obtaining the last error result is to declare your mapped method to throw `LastErrorException` instead.

  Indicates whether the system last error result is preserved after every invocation.

### getWindowID

    public static long getWindowID(Window w)
                            throws HeadlessException

  Utility method to get the native window ID for a Java `Window` as a `long` value. This method is primarily for X11-based systems, which use an opaque `XID` (usually `long int`) to identify windows.

  Throws:
    `HeadlessException` - if the current VM is running headless

### getComponentID

    public static long getComponentID(Component c)
                               throws HeadlessException

  Utility method to get the native window ID for a heavyweight Java `Component` as a `long` value. This method is primarily for X11-based systems, which use an opaque `XID` (usually `long int`) to identify windows.

  Throws:
    `HeadlessException` - if the current VM is running headless

### getWindowPointer

    public static Pointer getWindowPointer(Window w)
                                    throws HeadlessException

  Utility method to get the native window pointer for a Java `Window` as a `Pointer` value. This method is primarily for w32, which uses the `HANDLE` type (actually `void *`) to identify windows.

  Throws:
    `HeadlessException` - if the current VM is running headless

### getComponentPointer

    public static Pointer getComponentPointer(Component c)
                                       throws HeadlessException

  Utility method to get the native window pointer for a heavyweight Java `Component` as a `Pointer` value. This method is primarily for w32, which uses the `HWND` type (actually `void *`) to identify windows.

  Throws:
    `HeadlessException` - if the current VM is running headless

### getDirectBufferPointer

    public static Pointer getDirectBufferPointer(Buffer b)

  Convert a direct `Buffer` into a `Pointer`.

  Throws:
    `IllegalArgumentException` - if the buffer is not direct.

### toString

    public static String toString(byte[] buf)

  Obtain a Java String from the given native byte array. If there is no NUL terminator, the String will comprise the entire array. If the system property `jna.encoding` is set, its value will override the platform default encoding (if supported).

### toString

    public static String toString(byte[] buf,
                                  String encoding)

  Obtain a Java String from the given native byte array, using the given encoding. If there is no NUL terminator, the String will comprise the entire array. If the `encoding` parameter is null, the platform default encoding will be used.

### toString

    public static String toString(char[] buf)

  Obtain a Java String from the given native wchar_t array. If there is no NUL terminator, the String will comprise the entire array.

### loadLibrary

    public static Object loadLibrary(Class interfaceClass)

  Map a library interface to the current process, providing the explicit interface class.

  Parameters:
    `interfaceClass` -

### loadLibrary

    public static Object loadLibrary(Class interfaceClass,
                                     Map options)

  Map a library interface to the current process, providing the explicit interface class.

  Parameters:
    `interfaceClass` -
    `options` - Map of library options

### loadLibrary

    public static Object loadLibrary(String name,
                                     Class interfaceClass)

  Map a library interface to the given shared library, providing the explicit interface class. If `name` is null, attempts to map onto the current process.

  Parameters:
    `name` -
    `interfaceClass` -

### loadLibrary

    public static Object loadLibrary(String name,
                                     Class interfaceClass,
                                     Map options)

  Load a library interface from the given shared library, providing the explicit interface class and a map of options for the library. If no library options are detected the map is interpreted as a map of Java method names to native function names.

  If `name` is null, attempts to map onto the current process.

  Parameters:
    `name` -
    `interfaceClass` -
    `options` - Map of library options

### findEnclosingLibraryClass

    static Class findEnclosingLibraryClass(Class cls)

  Find the library interface corresponding to the given class. Checks all ancestor classes and interfaces for a declaring class which implements `Native.DeleteNativeLibrary`.

### getLibraryOptions

    public static Map getLibraryOptions(Class type)

  Return the preferred native library configuration options for the given class.

  See Also:
    `Native.DeleteNativeLibrary`

### getTypeMapper

    public static TypeMapper getTypeMapper(Class cls)

  Return the preferred `TypeMapper` for the given native interface. See `Library.OPTION_TYPE_MAPPER`.

### getStructureAlignment

    public static int getStructureAlignment(Class cls)

  Return the preferred structure alignment for the given native interface. See `Library.OPTION_STRUCTURE_ALIGNMENT`.

### getBytes

    static byte[] getBytes(String s)

  Return a byte array corresponding to the given String. If the system property `jna.encoding` is set, its value will override the default platform encoding (if supported).

### getBytes

    static byte[] getBytes(String s,
                           String encoding)
                    throws UnsupportedEncodingException

  Return a byte array corresponding to the given String, using the given encoding.

  Throws:
    `UnsupportedEncodingException`

### toByteArray

    public static byte[] toByteArray(String s)

  Obtain a NUL-terminated byte buffer equivalent to the given String, using `jna.encoding` or the default platform encoding if that property is not set.

### toByteArray

    public static byte[] toByteArray(String s,
                                     String encoding)
                              throws UnsupportedEncodingException

  Obtain a NUL-terminated byte buffer equivalent to the given String, using the given encoding.

  Throws:
    `UnsupportedEncodingException`

### toCharArray

    public static char[] toCharArray(String s)

  Obtain a NUL-terminated wide character buffer equivalent to the given String.

### getNativeLibraryResourcePath

    static String getNativeLibraryResourcePath(int osType,
                                               String arch,
                                               String name)

### getLastError

    public static int getLastError()

  Retrieve the last error set by the OS. This corresponds to `GetLastError()` on Windows, and `errno` on most other platforms. The value is preserved per-thread, but whether the original value is per-thread depends on the underlying OS. The result is undefined if `getPreserveLastError()` is `false`.

  The preferred method of obtaining the last error result is to declare your mapped method to throw `LastErrorException` instead.

### setLastError

    public static void setLastError(int code)

  Set the OS last error code. Whether the setting is per-thread or global depends on the underlying OS.

### updateLastError

    static void updateLastError(int e)

  Update the last error value (called from native code).

### synchronizedLibrary

    public static Library synchronizedLibrary(Library library)

  Returns a synchronized (thread-safe) library backed by the specified library. This wrapping will prevent simultaneous invocations of any functions mapped to a given `Native.DeleteNativeLibrary`. Note that the native library may still be sensitive to being called from different threads.

  Parameters:
    `library` - the library to be "wrapped" in a synchronized library.
  Returns:
    a synchronized view of the specified library.

### getWebStartLibraryPath

    public static String getWebStartLibraryPath(String libName)

  If running web start, determine the location of a given native library. This value may be used to properly set `jna.library.path` so that JNA can load libraries identified by the <nativelib> tag in the JNLP configuration file. Returns `null` if the Web Start native library cache location can not be determined. Note that the path returned may be different for any given library name.

  Use `System.getProperty("javawebstart.version")` to detect whether your code is running under Web Start.

  Returns:
    null if unable to query the web start loader.
  Throws:
    `UnsatisfiedLinkError` - if the library can't be found by the Web Start class loader, which usually means it wasn't included as a `<nativelib>` resource in the JNLP file.

### getNativeSize

    public static int getNativeSize(Class type,
                                    Object value)

  Returns the native size of the given class, in bytes. For use with arrays.

### getNativeSize

    public static int getNativeSize(Class cls)

  Returns the native size for a given Java class. Structures are assumed to be `struct` pointers unless they implement `Structure.ByValue`.

### isSupportedNativeType

    public static boolean isSupportedNativeType(Class cls)

  Indicate whether the given class is supported as a native argument type.

### setCallbackExceptionHandler

    public static void setCallbackExceptionHandler(Callback.UncaughtExceptionHandler eh)

  Set the default handler invoked when a callback throws an uncaught exception. If the given handler is `null`, the default handler will be reinstated.

### getCallbackExceptionHandler

    public static Callback.UncaughtExceptionHandler getCallbackExceptionHandler()

  Returns the current handler for callback uncaught exceptions.

### register

    public static void register(String libName)

  When called from a class static initializer, maps all native methods found within that class to native libraries via the JNA raw calling interface.

  Parameters:
    `libName` - library name to which functions should be bound

### register

    public static void register(NativeLibrary lib)

  When called from a class static initializer, maps all native methods found within that class to native libraries via the JNA raw calling interface.

  Parameters:
    `lib` - native library to which functions should be bound

### getNativeClass

    static Class getNativeClass(Class cls)

### getCallingClass

    static Class getCallingClass()

### unregister

    public static void unregister()

  Remove all native mappings for the calling class. Should only be called if the class is no longer referenced and about to be garbage collected.

### unregister

    public static void unregister(Class cls)

  Remove all native mappings for the given class. Should only be called if the class is no longer referenced and about to be garbage collected.

### replace

    static String replace(String s1,
                          String s2,
                          String str)

### register

    public static void register(Class cls,
                                NativeLibrary lib)

  When called from a class static initializer, maps all native methods found within that class to native libraries via the JNA raw calling interface.

  Parameters:
    `lib` - library to which functions should be bound

### ffi_prep_cif

    public static long ffi_prep_cif(int abi,
                                    int nargs,
                                    long ffi_return_type,
                                    long ffi_types)

### ffi_call

    public static void ffi_call(long cif,
                                long fptr,
                                long resp,
                                long args)

### ffi_prep_closure

    public static long ffi_prep_closure(long cif,
                                        Native.ffi_callback cb)

### ffi_free_closure

    public static void ffi_free_closure(long closure)

### initialize_ffi_type

    static int initialize_ffi_type(long type_info)

  Returns the size (calculated by libffi) of the given type.

### main

    public static void main(String[] args)

  Prints JNA library details to the console.

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Copyright © 2007-2010 Timothy Wall. All Rights Reserved.