Jni--java Call c&c++

Directly on the steps:

Writing Java code

Package cn.ace.jni; Public class testnative { Public native void SayHello (); Public Static void Main (string[] args) { } }

Use the Javah.exe tool to generate a header file cn_ace_jni_testnative.h

Build Method:

Execute the following command: Testnative is the name of the class

Generate File Contents:

/* Don't EDIT this file-it are machine generated */ #include <jni.h> /* Header for class cn_ace_jni_testnative */ #ifndef _included_cn_ace_jni_testnative #define _included_cn_ace_jni_testnative #ifdef __cplusplus extern "C" { #endif /* * Class:cn_ace_jni_testnative * Method:sayhello * Signature: () V */ jniexport void Jnicall Java_cn_ace_jni_testnative_sayhello (JNIENV *, jobject); #ifdef __cplusplus } #endif #endif

Write C + + code to generate a dynamic library

Create Project: MFC

Add cn_ace_jni_testnative.h to the project and copy the JDK-related files from the compile-time to the VC project directory (jni_md.h, jni.h) This file is D:\j2ee_lib\jdk1.6.0_10\include\ Directory under

Create C + + files, source.cpp content:

#include "cn_ace_jni_testnative.h" #include <iostream> using namespace Std; Jniexport void Jnicall Java_cn_ace_jni_testnative_sayhello (jnienv * env, Jobject obj) { cout<< "Hello world!" <<endl; }

Compile the project to generate TestNative.dll

Set TestNative.dll to System environment variable (PATH): D:\testc++\testnative\debug;

Writing Java code calls a dynamic library:

Package cn.ace.jni; Public class testnative { Public native void SayHello (); Public Static void Main (string[] args) { System. loadLibrary ("testnative"); Testnative testnative = new testnative (); Testnative.sayhello (); } }

Run after completion: An error appears as follows:

Cause: The environment variable you just set does not take effect, causing the path of the dynamic library to be found

Workaround: Restart Eclipse, as eclipse will load the environment variable at initial startup.

Exception in thread "main" Java.lang.UnsatisfiedLinkError:no testnative in Java.library.path At Java.lang.ClassLoader.loadLibrary (classloader.java:1709) At Java.lang.Runtime.loadLibrary0 (runtime.java:823) At Java.lang.System.loadLibrary (system.java:1030) At Cn.ace.jni.TestNative.main (testnative.java:8)

Jni--java Call c&c++