Java如何调用C/C++(JNI) 1. program Java source file loading Native method // // // NativeDemo // Author: huang_jc // file name: NativeDemo.java public class NativeDemo { int i; int j; public static void main(String args[]) { NativeDemo ob = new NativeDemo(); ob.i = 10; ob.j = ob.test(); System.out.println("this is ob.i:"+ob.i+"\n"); System.out.println("this is ob.j:"+ob.j); } public native int test(); static { System.loadLibrary("NativeDemo"); } }2.Compile file NativeDemo.java Javac NativeDemo.java3.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 */#ifndef _Included_NativeDemo #define _Included_NativeDemo#pragma pack(4)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:!\n"); printf("this is in the native method!\n"); 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 NativeDemowe get the such result:D:\vj11user\native>java NativeDemo hello:! this is in the native method! this is ob.i:10this is ob.j:20D:\vj11user\native> NOTE: Do not forget this: c:> set INCLUDE=d:\java\include;d:\java\win32;%INCLUDE% C:>set LIB =d:\java\lib;%LIB% where d:\java is the directory of your jdknew version jdk1.2.1 :With new jdk1.2.1 :1.javac NativeDemo.java2. 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.
//
//
// NativeDemo
// Author: huang_jc
// file name: NativeDemo.java
public class NativeDemo
{
int i;
int j;
public static void main(String args[])
{
NativeDemo ob = new NativeDemo();
ob.i = 10;
ob.j = ob.test();
System.out.println("this is ob.i:"+ob.i+"\n");
System.out.println("this is ob.j:"+ob.j);
}
public native int test();
static
{
System.loadLibrary("NativeDemo");
}
}2.Compile file NativeDemo.java
Javac NativeDemo.java3.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 */#ifndef _Included_NativeDemo
#define _Included_NativeDemo#pragma pack(4)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:!\n");
printf("this is in the native method!\n");
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 NativeDemowe get the such result:D:\vj11user\native>java NativeDemo
hello:!
this is in the native method!
this is ob.i:10this is ob.j:20D:\vj11user\native>
NOTE:
Do not forget this:
c:> set INCLUDE=d:\java\include;d:\java\win32;%INCLUDE%
C:>set LIB =d:\java\lib;%LIB%
where d:\java is the directory of your jdknew version jdk1.2.1 :With new jdk1.2.1 :1.javac NativeDemo.java2. 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.
配置运行环境要点手续吧?给点tips吧
module HelloApp
{
interface Hello
{
string sayHello();
};
};
如何做到呢?1
具体怎么实现光靠几个例子是不够的。
以前我买到过一本将C++编corba的书,但不知现在还有吗。
挺方便的。