3.Use javah.exe to prodUCe file NativeDemo.c and NativeDemo.h a : javah NativeDemo to produce NativeDemo.h which is: /* DO NOT EDIT THIS FILE - it is machine generated */ #include <native.h> /* Header for class NativeDemo */
typedef struct ClassNativeDemo { long i; long j; } ClassNativeDemo; HandleTo(NativeDemo);
#pragma pack()
#ifdef __cplusplus extern "C" { #endif extern long NativeDemo_test(struct HNativeDemo *); #ifdef __cplusplus } #endif #endif b : use javah -stubs NativeDemo to produce NativeDemo.c which seems as: /* DO NOT EDIT THIS FILE - it is machine generated */ #include <StubPreamble.h>
/* Stubs for class NativeDemo */ /* SYMBOL: "NativeDemo/test()I", Java_NativeDemo_test_stub */ __declspec(dlleXPort) stack_item *Java_NativeDemo_test_stub(stack_item *_P_,struct execenv *_EE_) { extern long NativeDemo_test(void *); _P_[0].i = NativeDemo_test(_P_[0].p); return _P_ + 1; } 4. Write your own implimentation of method test() //file name test.c #include <StubPreamble.h> #include "nativedemo.h" #include <stdio.h>
long NativeDemo_test(HNativeDemo *this) { printf("hello:!"); printf("this is in the native method!"); return (unhand(this)->i)*2; }
5. link NativeDemo.c and test.c to produce NativeDemo.dll Use VC++5.0 tools :Cl.exe Cl /GD NativeDemo.c test.c /LD then we get NativeDemo.dll
NativeDemo.c test.c Generating Code...
/out:NativeDemo.dll /dll /implib:NativeDemo.lib NativeDemo.obj test.obj Creating library NativeDemo.lib and object NativeDemo.ex Press any key to continue
6.Run
java NativeDemo
we get the such result:
D:vj11userative>java NativeDemo hello:! this is in the native method! this is ob.i:10
this is ob.j:20
D:vj11userative>
NOTE: Do not forget this: c:> set INCLUDE=d:javainclude;d:javawin32;%INCLUDE% C:>set LIB =d:javalib;%LIB% where d:java is the Directory of your jdk
new version jdk1.2.1 :
With new jdk1.2.1 :
1.javac NativeDemo.java
2. javah NativeDemo to produce head file (You need not to javah -stubs NativeDemo to produce NativeDemo.c file),
You don`t need the c file. Just the NativeDemo.h is sufficient!
3.Use VC++ produce a window dll project and add the NativeDemo.h to it.
then implement the function. All is OK! NOTE: the data type conversion between java and c++.See jni.h for more information.
