1、從http://www.oracle.com/technetwork/java/javase/downloads/jdk-7u2-download-1377129.html下載jdk-7u2-windows-i586.exe，安裝到D:\ProgramFiles\Java，并將D:\ProgramFiles\Java\jdk1.7.0_02\bin添加到環境變量中；

2、從http://www.eclipse.org/downloads/下載eclipse-java-indigo-SR1-win32.zip并解壓縮；

3、打開Eclipse，File-->new-->Java Project-->Project Name:TestJavaJNI-->next-->Finish,選中TestJavaJNI,點擊右鍵-->new-->class-->Name:TestJNI，編寫Java類：

publicclass TestJNI

{

??? public nativeint add(int a,int b);

??? public native String upperCase(String str);

???

??? static

??? {

?????? System.loadLibrary("JniDll");

??? }

???

??? public staticvoid main(String[] args)

??? {

?????? TestJNI test = new TestJNI();

??????

?????? int a=10, b=20, result;

??????

?????? result = test.add(a, b);

??????

?????? System.out.println("兩者的和為： " + result);

??????

?????? String str1, str2;

??????

?????? str1 = "abcDEFhijk";

??????

?????? str2 = test.upperCase(str1);

??????

?????? System.out.println(str2);

??? }

}

?

4、打開命令行窗口，進入到TestJNI所在目錄下，執行 javac TestJNI.java命令，編譯完成后生成TestJNI.class文件；

5、執行javah TestJNI命令，生成TestJNI.h頭文件；

6、打開vs2008，新建一個控制臺程序，選中DLL和Empty project,將TestJNI.h復制到此工程目錄下，并添加到工程中，新建一.cpp文件，包含jdk相應文件，Tools-->Options-->vc++ Directories-->include files: D:\ProgramFiles(x86)\Java\jdk1.7.0_02\include?

D:\ProgramFiles(x86)\Java\jdk1.7.0_02\include\win32

?

#include <iostream>

#include <string>

?

#include "TestJNI.h"

?

using namespace std;

?

jstring str2jstring(JNIEnv*env,const char* pat)

{????

??? //定義java String類strClass

??? jclassstrClass = (env)->FindClass("Ljava/lang/String;");

?

??? //獲取String(byte[],String)的構造器,用于將本地byte[]數組轉換為一個新String

??? jmethodIDctorID = (env)->GetMethodID(strClass,"<init>","([BLjava/lang/String;)V");

?

??? //建立byte數組

??? jbyteArraybytes = (env)->NewByteArray(strlen(pat));

?

??? //將char*轉換為byte數組

??? (env)->SetByteArrayRegion(bytes, 0,strlen(pat), (jbyte*)pat);

?

??? // 設置String, 保存語言類型,用于byte數組轉換至String時的參數

??? jstringencoding = (env)->NewStringUTF("GB2312");

?

??? //將byte數組轉換為java String,并輸出

??? return (jstring)(env)->NewObject(strClass,ctorID,bytes,encoding);

}????

?

string jstring2str(JNIEnv*env,jstringjstr)

{???????

??? char*??rtn?? =??NULL;

??? jclass??clsstring?? =??env->FindClass("java/lang/String");

??? jstring??strencode?? =??env->NewStringUTF("GB2312");

??? jmethodID??mid?? =??env->GetMethodID(clsstring,??"getBytes",??"(Ljava/lang/String;)[B");

??? jbyteArray??barr=?? (jbyteArray)env->CallObjectMethod(jstr,mid,strencode);

??? jsize??alen?? =??env->GetArrayLength(barr);

??? jbyte*??ba?? =??env->GetByteArrayElements(barr,JNI_FALSE);

?

??? if(alen?? >?? 0)?????

??? {???????????

??????? rtn?? =?? (char*)malloc(alen+1);?

??????? memcpy(rtn,ba,alen);?????????

??????? rtn[alen]=0;??????

??? }?

?

??? env->ReleaseByteArrayElements(barr,ba,0);

?

??? stringstemp(rtn);

?

??? free(rtn);???

?

??? return??stemp;??

}

?

JNIEXPORTjint JNICALLJava_TestJNI_add(JNIEnv *env,jobject,jinta,jint b)

{

??? int result = (int)(a +b);

?

??? return (jint)result;

}

?

JNIEXPORTjstring JNICALLJava_TestJNI_upperCase(JNIEnv *env,jobject,jstringstr)

{

??? stringstrUpper;

?

??? strUpper =jstring2str(env,str);

?

??? strUpper = (string)strupr((char*)strUpper.c_str());

?

??? jstringstrResult =str2jstring(env,strUpper.c_str());

?

??? return strResult;

}

?

7、將生成的動態庫JniDll.dll(Release or Debug)復制到TestJNI.java同一目錄下，執行java TestJNI即可顯示最終結果，也可以復制JniDll.dll到與src同一目錄下，在Eclipse中點擊Run即可，運行結果：

兩者的和為： 30

ABCDEFHIJK

?

參考文獻：

1、? http://blog.csdn.net/mingjava/article/details/180946

2、? http://www.blogjava.net/china-qd/archive/2006/04/29/44002.html

3、? http://www.189works.com/article-42158-1.html

4、? http://www.chineselinuxuniversity.net/articles/39361.shtml

5、? http://www.cnblogs.com/lichien/archive/2011/10/11/2206828.html