Integrating Java and Native Programs

JNI�� ϴ� �� ȣ��ϴ� �� ؼ� ǥ�� ִ�. ��⿡�� ̷�� ؼ� �� ϰ� �ȴ�. �� Ÿ�� ϴ� �� ؼ�� Ѵ�.

Declaring Native Methods

Java �ʿ�� native Ű��带 ��ؼ� native �ڵ带 ��ϰڴٴ� �� ˸��, native ��ʿ�� ϰ� �Ǵµ�, �� ̿� ��踦 �� ִ� �ڵ� �� ̿��ؾ� �Ѵ�. javah�� Ÿ�� ְ� �ȴ�.

Mapping between Java and Native Types

JNI�� Java�� Ÿ�԰� native �� Ÿ�� ִ� Ÿ�� Ѵ�. �� 忡�� Ϲ�� int�� double�� primitive Ÿ�� ϴ� ��Ӹ� �ƴ϶� Java ��ü�� ִ� �� ؼ� ��Ѵ�.

Declaring Native Methods

��⿡�� Java�� native �޼ҵ�� C/C++ �Լ� ��Ÿ�� Ű�� ؼ� ��Ѵ�.

The Java side

�� Java �ҽ�� .

class Prompt {
private native String getLine(String prompt);
public static void main(String args[]) {
    Prompt p = new Prompt();
    String input = p.getLine("Type a line: ");
    System.out.println("User typed: " + input);
}
static {
    System.loadLibrary("MyImpOfPrompt");
}
}

native �޼ҵ�� getLine() �̴�. native �޼ҵ带 ��ϴ� �� .

native Ű��带 ��ؾ� �Ѵ�.
��ڵ尡 ���� ʰ�, �� ݷи�� .

The Native Language Side

��ϴ� �� Ű�� ؼ� �̹� �տ�� Ǿ��. javah�� Ÿ�� .

JNIEXPORT jstring JNICALL Java_Prompt_getLine(JNIEnv *, jobject, jstring)

��ϴ� �� ؼ�� տ�� ̹� �� Ǿ��, JNIEXPORT�� JNICALL�� ÷�� Ű��̴�.

Mapping Between Java and Native Types

��⿡�� Ǵ� �� native �ڵ忡�� ۷�� Java Ÿ��̴�. �� Ÿ�� 뵵�� ϱ� ��ؼ� �ʿ��ϴ�.

Java ��α׷��κ�� Ѱ�� μ�� ϰ��
native �޼ҵ忡�� Java ��ü�� ϰ��
native �޼ҵ�� ȣ��ڷ� ��ϰ��

Java Primitive Types

Java primitive Ÿ�԰� �̿� ��Ǵ� native Ÿ�� ǥ�� .

Java Type	Native Type	Size in bits
boolean	jboolean	8, unsigned
byte	jbyte	8
char	jchar	16, unsigned
short	jshort	16
int	jint	32
long	jlong	64
float	jfloat	32
double	jdouble	64
void	void	n/a

Java Object Types

Java ��ü�� ۷�� Ѱ��. �� μ�� Ѱ�� ü�� jobject�� Ŭ�� ȴ�. �� ׸�� Ÿ�� ̴�.

�� ׸�� getLine() �Լ�� �� Ǵ�� Ÿ��.