Native libraries are loaded via System#loadLibrary(String), System#load(String), Runtime#loadLibrary(String) and Runtime#load(String). They are caller-sensitive. Each class loader has a NativeLibraries instance to register all of its loaded native libraries. System::loadLibrary (and other APIs) only allows a native library to be loaded by one class loader, i.e. one NativeLibraries instance. Any attempt to load a native library that has already been loaded by a class loader with another class loader will fail.

Nested and Inner Type Summary

Modifier and Type	Class and Description
private static class	NativeLibraries.CountedLock
pack-priv static class	NativeLibraries.LibraryPaths
private static class	NativeLibraries.NativeLibraryContext
pack-priv static class	NativeLibraries.NativeLibraryImpl NativeLibraryImpl denotes a loaded native library instance.
pack-priv static class	NativeLibraries.Unloader

Field Summary

Modifier and Type	Field and Description
private final Class<?>	caller
private final Map<String, NativeLibraries.NativeLibraryImpl>	libraries
private static final Set<String>	loadedLibraryNames
private final ClassLoader	loader
private static final boolean	loadLibraryOnlyIfPresent
private static final Map<String, NativeLibraries.CountedLock>	nativeLibraryLockMap
private final boolean	searchJavaLibraryPath

Access	Constructor and Description
private	NativeLibraries(ClassLoader loader, Class<?> caller, boolean searchJavaLibraryPath)

Method Summary

Modifier and Type	Method and Description
private static void	acquireNativeLibraryLock(String libraryName)
public long	find(String name)
private static native String	findBuiltinLib(String name)
private NativeLibrary	findFromPaths(String[] paths, Class<?> fromClass, String name)
private static Class<?>	getFromClass()
private static native boolean	load(NativeLibraries.NativeLibraryImpl impl, String name, boolean isBuiltin, boolean throwExceptionIfFail)
public NativeLibrary	loadLibrary(Class<?> fromClass, File file)
private NativeLibrary	loadLibrary(Class<?> the caller class calling System::loadLibrary fromClass, String library name name, boolean built-in library isBuiltin) Returns a NativeLibrary of the given name.
public NativeLibrary	loadLibrary(String library name name) Loads a native library from the system library path and java library path.
public NativeLibrary	loadLibrary(Class<?> the caller class calling System::loadLibrary fromClass, String library name name) Loads a native library from the system library path and java library path.
public static NativeLibraries	newInstance(ClassLoader loader) Creates a NativeLibraries instance for loading JNI native libraries via for System::loadLibrary use.
private static void	releaseNativeLibraryLock(String libraryName)
private static native void	unload(String name, boolean isBuiltin, long handle)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

caller	back to summary
private final Class<?> caller

libraries	back to summary
private final Map<String, NativeLibraries.NativeLibraryImpl> libraries

loadedLibraryNames	back to summary
private static final Set<String> loadedLibraryNames

loader	back to summary
private final ClassLoader loader

loadLibraryOnlyIfPresent	back to summary
private static final boolean loadLibraryOnlyIfPresent

nativeLibraryLockMap	back to summary
private static final Map<String, NativeLibraries.CountedLock> nativeLibraryLockMap

searchJavaLibraryPath	back to summary
private final boolean searchJavaLibraryPath

NativeLibraries	back to summary
private NativeLibraries(ClassLoader loader, Class<?> caller, boolean searchJavaLibraryPath)

Method Detail

acquireNativeLibraryLock	back to summary
private static void acquireNativeLibraryLock(String libraryName)

find	back to summary
public long find(String name)

findBuiltinLib	back to summary
private static native String findBuiltinLib(String name)

findFromPaths	back to summary
private NativeLibrary findFromPaths(String[] paths, Class<?> fromClass, String name)

getFromClass	back to summary
private static Class<?> getFromClass()

load	back to summary
private static native boolean load(NativeLibraries.NativeLibraryImpl impl, String name, boolean isBuiltin, boolean throwExceptionIfFail)

loadLibrary	back to summary
public NativeLibrary loadLibrary(Class<?> fromClass, File file) Annotations @SuppressWarnings:removal

loadLibrary	back to summary
private NativeLibrary loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) Returns a NativeLibrary of the given name. Parameters fromClass:Class<?> the caller class calling System::loadLibrary name:String library name isBuiltin:boolean built-in library Exceptions UnsatisfiedLinkError: if the native library has already been loaded and registered in another NativeLibraries

loadLibrary

back to summary

private NativeLibrary loadLibrary(Class<?> fromClass, String name, boolean isBuiltin)

Returns a NativeLibrary of the given name.

Parameters

fromClass:Class<?>: the caller class calling System::loadLibrary
name:String: library name
isBuiltin:boolean: built-in library

Exceptions

UnsatisfiedLinkError:: if the native library has already been loaded and registered in another NativeLibraries

loadLibrary	back to summary
public NativeLibrary loadLibrary(String name) Loads a native library from the system library path and java library path. Parameters name:String library name Exceptions UnsatisfiedLinkError: if the native library has already been loaded and registered in another NativeLibraries

loadLibrary

back to summary

public NativeLibrary loadLibrary(String name)

Loads a native library from the system library path and java library path.

Parameters

name:String: library name

Exceptions

UnsatisfiedLinkError:: if the native library has already been loaded and registered in another NativeLibraries

loadLibrary	back to summary
public NativeLibrary loadLibrary(Class<?> fromClass, String name) Loads a native library from the system library path and java library path. Parameters fromClass:Class<?> the caller class calling System::loadLibrary name:String library name Exceptions UnsatisfiedLinkError: if the native library has already been loaded and registered in another NativeLibraries

loadLibrary

back to summary

public NativeLibrary loadLibrary(Class<?> fromClass, String name)

Loads a native library from the system library path and java library path.

Parameters

fromClass:Class<?>: the caller class calling System::loadLibrary
name:String: library name

Exceptions

UnsatisfiedLinkError:: if the native library has already been loaded and registered in another NativeLibraries

newInstance	back to summary
public static NativeLibraries newInstance(ClassLoader loader) Creates a NativeLibraries instance for loading JNI native libraries via for System::loadLibrary use. 1. Support of auto-unloading. The loaded native libraries are unloaded when the class loader is reclaimed. 2. Support of linking of native method. See JNI spec. 3. Restriction on a native library that can only be loaded by one class loader. Each class loader manages its own set of native libraries. The same JNI native library cannot be loaded into more than one class loader. This static factory method is intended only for System::loadLibrary use. See Also JNI Specification: Library and Version Management

newInstance

back to summary

public static NativeLibraries newInstance(ClassLoader loader)

Creates a NativeLibraries instance for loading JNI native libraries via for System::loadLibrary use. 1. Support of auto-unloading. The loaded native libraries are unloaded when the class loader is reclaimed. 2. Support of linking of native method. See JNI spec. 3. Restriction on a native library that can only be loaded by one class loader. Each class loader manages its own set of native libraries. The same JNI native library cannot be loaded into more than one class loader. This static factory method is intended only for System::loadLibrary use.

See Also: JNI Specification: Library and Version Management

releaseNativeLibraryLock	back to summary
private static void releaseNativeLibraryLock(String libraryName)

unload	back to summary
private static native void unload(String name, boolean isBuiltin, long handle)

jdk.internal.loader back to summary

private final Class NativeLibraries.CountedLock

Class Inheritance

extends ReentrantLock

java.lang.Object
java.util.concurrent.locks.ReentrantLock
jdk.internal.loader.NativeLibraries.CountedLock

Annotations

@SuppressWarnings:serial

Field Summary

Modifier and Type	Field and Description
private int	counter

Constructor Summary

Access	Constructor and Description
private	CountedLock()

Method Summary

Modifier and Type	Method and Description
public void	decrement()
public int	getCounter()
public void	increment()

Field Detail

counter	back to summary
private int counter

Constructor Detail

CountedLock	back to summary
private CountedLock()

Method Detail

decrement	back to summary
public void decrement()

getCounter	back to summary
public int getCounter()

increment	back to summary
public void increment()

jdk.internal.loader back to summary

pack-priv Class NativeLibraries.LibraryPaths

Class Inheritance

extends Object

java.lang.Object
jdk.internal.loader.NativeLibraries.LibraryPaths

Field Summary

Modifier and Type	Field and Description
pack-priv static final String[]	SYS_PATHS
pack-priv static final String[]	USER_PATHS

Constructor Summary

Access	Constructor and Description
pack-priv	LibraryPaths()

Method Summary

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

SYS_PATHS	back to summary
pack-priv static final String[] SYS_PATHS

USER_PATHS	back to summary
pack-priv static final String[] USER_PATHS

Constructor Detail

LibraryPaths	back to summary
pack-priv LibraryPaths()

jdk.internal.loader back to summary

private final Class NativeLibraries.NativeLibraryContext

Class Inheritance

extends Object

java.lang.Object
jdk.internal.loader.NativeLibraries.NativeLibraryContext

Field Summary

Modifier and Type	Field and Description
private static Map<Thread, Deque<NativeLibraries.NativeLibraryImpl>>	nativeLibraryThreadContext

Constructor Summary

Access	Constructor and Description
private	NativeLibraryContext()

Method Summary

Modifier and Type	Method and Description
private static Deque<NativeLibraries.NativeLibraryImpl>	current()
private static boolean	isEmpty()
private static NativeLibraries.NativeLibraryImpl	peek()
private static void	pop()
private static void	push(NativeLibraries.NativeLibraryImpl lib)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

nativeLibraryThreadContext	back to summary
private static Map<Thread, Deque<NativeLibraries.NativeLibraryImpl>> nativeLibraryThreadContext

Constructor Detail

NativeLibraryContext	back to summary
private NativeLibraryContext()

Method Detail

current	back to summary
private static Deque<NativeLibraries.NativeLibraryImpl> current()

isEmpty	back to summary
private static boolean isEmpty()

peek	back to summary
private static NativeLibraries.NativeLibraryImpl peek()

pop	back to summary
private static void pop()

push	back to summary
private static void push(NativeLibraries.NativeLibraryImpl lib)

jdk.internal.loader back to summary

pack-priv Class NativeLibraries.NativeLibraryImpl

Class Inheritance

extends NativeLibrary

java.lang.Object
jdk.internal.loader.NativeLibrary
jdk.internal.loader.NativeLibraries.NativeLibraryImpl

NativeLibraryImpl denotes a loaded native library instance. Each NativeLibraries contains a map of loaded native libraries in the private field libraries. Every native library requires a particular version of JNI. This is denoted by the private jniVersion field. This field is set by the VM when it loads the library, and used by the VM to pass the correct version of JNI to the native methods.

Field Summary

Modifier and Type	Field and Description
pack-priv final Class<?>	fromClass
pack-priv long	handle
pack-priv final boolean	isBuiltin
pack-priv int	jniVersion
pack-priv final String	name

Constructor Summary

Access	Constructor and Description
pack-priv	NativeLibraryImpl(Class<?> fromClass, String name, boolean isBuiltin)

Method Summary

Modifier and Type	Method and Description
pack-priv void	close()
public long	find(String the name of the symbol to be found name) Implements abstract jdk.internal.loader.NativeLibrary.find. Finds the address of the entry of the given name.
public String	name() Implements abstract jdk.internal.loader.NativeLibrary.name.
pack-priv boolean	open()
private boolean	throwExceptionIfFail()
private Runnable	unloader()

Inherited from jdk.internal.loader.NativeLibrary:: findEntry0 lookup

Field Detail

fromClass	back to summary
pack-priv final Class<?> fromClass

handle	back to summary
pack-priv long handle

isBuiltin	back to summary
pack-priv final boolean isBuiltin

jniVersion	back to summary
pack-priv int jniVersion

name	back to summary
pack-priv final String name

Constructor Detail

NativeLibraryImpl	back to summary
pack-priv NativeLibraryImpl(Class<?> fromClass, String name, boolean isBuiltin)

Method Detail

close	back to summary
pack-priv void close()

find

back to summary

public long find(String name)

Implements abstract jdk.internal.loader.NativeLibrary.find.

Doc from jdk.internal.loader.NativeLibrary.find.

Finds the address of the entry of the given name. Returns 0 if not found.

Parameters

name:String: the name of the symbol to be found

Annotations

@Override

name

back to summary

public String name()

Implements abstract jdk.internal.loader.NativeLibrary.name.

Annotations

@Override

open	back to summary
pack-priv boolean open()

throwExceptionIfFail	back to summary
private boolean throwExceptionIfFail() Annotations @SuppressWarnings:removal

unloader	back to summary
private Runnable unloader()

jdk.internal.loader back to summary

pack-priv Class NativeLibraries.Unloader

Class Inheritance

extends Object
implements Runnable

java.lang.Object
jdk.internal.loader.NativeLibraries.Unloader

All Implemented Interfaces

java.lang.Runnable

Field Summary

Modifier and Type	Field and Description
pack-priv final long	handle
pack-priv final boolean	isBuiltin
pack-priv final String	name
pack-priv static final NativeLibraries.NativeLibraryImpl	UNLOADER

Constructor Summary

Access	Constructor and Description
pack-priv	Unloader(String name, long handle, boolean isBuiltin)

Method Summary

Modifier and Type	Method and Description
public void	run() Implements java.lang.Runnable.run. Runs this operation.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

handle	back to summary
pack-priv final long handle

isBuiltin	back to summary
pack-priv final boolean isBuiltin

name	back to summary
pack-priv final String name

UNLOADER	back to summary
pack-priv static final NativeLibraries.NativeLibraryImpl UNLOADER

Constructor Detail

Unloader	back to summary
pack-priv Unloader(String name, long handle, boolean isBuiltin)

Method Detail

run

back to summary

public void run()

Implements java.lang.Runnable.run.

Doc from java.lang.Runnable.run.

Runs this operation.

Annotations

@Override

public final Class NativeLibraries

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private final Class NativeLibraries.CountedLock

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv Class NativeLibraries.LibraryPaths

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

private final Class NativeLibraries.NativeLibraryContext

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv Class NativeLibraries.NativeLibraryImpl

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv Class NativeLibraries.Unloader

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail