基本数据类型的传递

第一步： 编写java

public class HelloWorld{

    static {
        System.loadLibrary("native");
    }
    
    public native int getInt(int in);
    public native boolean getBoolen(boolean bol);
    public native byte getByte(byte by);
    public native long getLong(long lo);
    public native char getChar(char ch);
    public native double getDouble(double db);
    public native short getShort(short sh);
    public native float getFloat(float fl);

    public static void main(String[] args) {
        HelloWorld world=new HelloWorld();
        System.out.println("Int :"+world.getInt(10));
        System.out.println("Boolen :"+world.getBoolen(false));
        System.out.println("Long :"+world.getLong(10000));
        System.out.println("Char :"+world.getChar('a'));
        System.out.println("Double :"+world.getDouble(12.12));
        System.out.println("Short :"+world.getShort((short)12));
        System.out.println("Float :"+world.getFloat(10.00f));
    }   
}

第二步： 编译、获取，更改JNI头文件名

$ javac HelloWorld.java
$ javah HelloWorld
$ mv HelloWorld.h  HelloWorld.c

第三步完成JNI文件的编写

#include <jni.h>

JNIEXPORT jint JNICALL Java_HelloWorld_getInt
  (JNIEnv * env, jobject job, jint jin){
    return jin*jin;
  }

JNIEXPORT jboolean JNICALL Java_HelloWorld_getBoolen
  (JNIEnv *env, jobject job, jboolean jb)
  {
    return !jb;
  }

JNIEXPORT jbyte JNICALL Java_HelloWorld_getByte
  (JNIEnv * env, jobject job, jbyte bt){
    return bt+1;
  }

JNIEXPORT jlong JNICALL Java_HelloWorld_getLong
  (JNIEnv * env, jobject job, jlong jl){
    return jl*jl;
  } 


JNIEXPORT jchar JNICALL Java_HelloWorld_getChar
  (JNIEnv * env, jobject jb, jchar jc){
    return jc-('a'-'A');
  }

JNIEXPORT jdouble JNICALL Java_HelloWorld_getDouble
  (JNIEnv * env, jobject jo, jdouble jd){
    return jd*2;
  }


JNIEXPORT jshort JNICALL Java_HelloWorld_getShort
  (JNIEnv * jnv , jobject job, jshort js){
    return js*2.0;
  }


JNIEXPORT jfloat JNICALL Java_HelloWorld_getFloat
  (JNIEnv * env, jobject job, jfloat jf){
    return jf*2;
  }

第四步： 编译

$ gcc HelloWorld.c -shared -fPIC -o libnative.so -I /usr/lib/jvm/java-7-openjdk-amd64/include/

第五步：设置程序共享库位置

$ export LD_LIBRARY_PATH=.

第六步：执行java程序

$ java HelloWorld

成功打印！

Int :100
Boolen :true
Long :100000000
Char :A
Double :24.24
Short :24
Float :20.0

下一节讲解引用数据类型的传递