eu.aschuetz.nativeutils.api

Interface JVMNativeUtil

All Superinterfaces:

NativeUtil

public interface JVMNativeUtil
extends NativeUtil

Method Summary

Modifier and Type	Method and Description
<T> T	AllocObject(Class<T> clazz) creates a instance of a object without calling a constructor.
Class<?>	DefineClass(String name, ClassLoader loader, byte[] bytes, int off, int len) Defines a class in the given classloader.
void	DeleteGlobalRef(long ref) Deletes a global ref.
NativeField	FromReflectedField(Field field) Gets a native reference to a java field from a given Reflection field.
<R> NativeMethod<R,R>	FromReflectedMethod(Constructor<R> method) reflection constructor to native method.
NativeMethod	FromReflectedMethod(Method method) reflection method to native method.
long	GetDirectBufferAddress(ByteBuffer buffer) returns the native address of a direct byte buffer.
NativeMemory	GetDirectBufferAddress(ByteBuffer buffer, int off, int size) Returns a NativeMemory object that uses the direct byte buffer object as backing.
<T,X> NativeField<T,X>	GetFieldID(Class<T> clazz, String fieldName, String signature) Gets a native reference to a java field.
<R,D> NativeMethod<R,D>	GetMethodID(Class<D> declaring, String name, String signature) Get non static native method by signature
<T,X> NativeField<T,X>	GetStaticFieldID(Class<T> clazz, String fieldName, String signature) Gets a native reference to a java field.
<R,D> NativeMethod<R,D>	GetStaticMethodID(Class<D> declaring, String name, String signature) Get static native method by signature
void	MonitorEnter(Object obj) Enter a monitor.
void	MonitorExit(Object obj) Exit from a monitor entered by MonitorEnter.
ByteBuffer	NewDirectByteBuffer(long ptr, long capacity) returns a direct byte buffer using the given pointer and capacity.
long	NewGlobalRef(Object obj) returns a global reference that can be stored to a java object.
<T> T	NewLocalRef(long ref) Resolves a Global ref into a "object".
RuntimeException	Throw(Throwable throwable) This method allows throwing of checked exceptions in methods that do not declare them as checked exceptions.

Methods inherited from interface eu.aschuetz.nativeutils.api.NativeUtil

isJVM, isLinux, isNoop, isWindows

Method Detail

DefineClass

Class<?> DefineClass(String name,
                     ClassLoader loader,
                     byte[] bytes,
                     int off,
                     int len)
              throws ClassFormatError,
                     ClassCircularityError,
                     SecurityException

Defines a class in the given classloader.

Parameters:

name - MUST BE IN JNI NOTATION. for example "org.example.MyClass" would be "org/example/MyClass"

Returns:

the defined class

Throws:

ClassFormatError - if the bytes in buf are not a valid class

ClassCircularityError - if the class would be its own superclass

SecurityException - if name starts with "java."

MonitorEnter

void MonitorEnter(Object obj)

Enter a monitor. This is equivalent to the beginning of a synchronized block/method.

MonitorExit

void MonitorExit(Object obj)

Exit from a monitor entered by MonitorEnter. This MUST NOT be used to leave a monitor acquired by a synchronized block/method.

GetDirectBufferAddress

long GetDirectBufferAddress(ByteBuffer buffer)

returns the native address of a direct byte buffer.

NewDirectByteBuffer

ByteBuffer NewDirectByteBuffer(long ptr,
                               long capacity)

returns a direct byte buffer using the given pointer and capacity.

GetDirectBufferAddress

NativeMemory GetDirectBufferAddress(ByteBuffer buffer,
                                    int off,
                                    int size)

Returns a NativeMemory object that uses the direct byte buffer object as backing. This method ensures that the buffer object is not garbage collected until the close() method of the NativeMemory object is called. The resulting NativeMemory Object does not modify the buffer position. The resulting NativeMemory Object is bound by off and size. Off is relative to the start of the buffer not the current position of the buffer.

AllocObject

<T> T AllocObject(Class<T> clazz)

creates a instance of a object without calling a constructor.

NewGlobalRef

long NewGlobalRef(Object obj)

returns a global reference that can be stored to a java object. The given java object will not be garbage collected/finalized unless DeleteGlobalRef is called with the returned value

Returns:

opaque native reference long. This value must NEVER be modified or the DeleteGlobalRef/NewLocalRef method will crash the jvm if a modified value is used.

Throws:

NullPointerException - if obj is null

DeleteGlobalRef

void DeleteGlobalRef(long ref)

Deletes a global ref. After deletion the ref must no longer be used. if the Object referred to by the given ref is no longer referenced elsewhere it will be garbage collected. If a "ref" long value is used after calling DeleteGlobalRef the jvm may crash.

NewLocalRef

<T> T NewLocalRef(long ref)

Resolves a Global ref into a "object". Note: you can safely use the object even after DeleteGlobalRef has already been called on the ref passed to this method.

Throw

RuntimeException Throw(Throwable throwable)

This method allows throwing of checked exceptions in methods that do not declare them as checked exceptions.

Returns:

never returns without throwing an exception. Return type RuntimeException only exists to trick compiler to allow for "throw util.Throw(...)" pattern

Throws:

NullPointerException - if the given throwable is null

Throwable - the given throwable

FromReflectedMethod

NativeMethod FromReflectedMethod(Method method)

reflection method to native method.

FromReflectedMethod

<R> NativeMethod<R,R> FromReflectedMethod(Constructor<R> method)

reflection constructor to native method.

GetMethodID

<R,D> NativeMethod<R,D> GetMethodID(Class<D> declaring,
                                    String name,
                                    String signature)

Get non static native method by signature

GetStaticMethodID

<R,D> NativeMethod<R,D> GetStaticMethodID(Class<D> declaring,
                                          String name,
                                          String signature)

Get static native method by signature

FromReflectedField

NativeField FromReflectedField(Field field)

Gets a native reference to a java field from a given Reflection field.

GetFieldID

<T,X> NativeField<T,X> GetFieldID(Class<T> clazz,
                                  String fieldName,
                                  String signature)

Gets a native reference to a java field.

Parameters:

clazz - the class the field is in

fieldName - the field name

signature - the signature of the field type

Returns:

null if the field was not found.

GetStaticFieldID

<T,X> NativeField<T,X> GetStaticFieldID(Class<T> clazz,
                                        String fieldName,
                                        String signature)

Gets a native reference to a java field.

Parameters:

clazz - the class the field is in

fieldName - the field name

signature - the signature of the field type

Returns:

null if the field was not found.