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1. program Java source file loading Native method // 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+" "); System.out.println("this is ob.j:"+ob.j); } public native int test(); static { System.loadLibrary("NativeDemo"); } } 2.Compile file NativeDemo.java Javac NativeDemo.java 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 */ #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:! "); 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:vj11user ative>java NativeDemo hello:! this is in the native method! this is ob.i:10 this is ob.j:20 D:vj11user ative> 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. 返回类别: 教程 上一教程: 在JSP中用BEAN和SERVLET联合实现用户注册、登录 下一教程: DATE类的简朴应用 您可以阅读与"JAVA如何调用C/C++(JNI)"相关的教程: · 如何调用JAVABEAN · Java如何调用可执行文件和批处理命令 · JAVA-如何实现TIMER功能 · 分别用java Application 及 JSP调用javaBean的例子 · Applet调用JavaScript函数 |
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