Java JNI 入门篇——传递数组与修改数组

package com.example.jni;

public class ArrayJNI {
static {
System.loadLibrary("arrayjni");
}

public native byte[] process(byte[] data);

public static void main(String[] args) throws Exception {
byte[] srcbyte = new byte[] { 1, 2, 3 };
ArrayJNI item = new ArrayJNI();
byte[] resultbyte = item.process(srcbyte);
System.out.print("(Java)result byte: ");
for (int i = 0; i < resultbyte.length; i++) {
System.out.printf("%d\t", 0xff & resultbyte[i]);
}
System.out.println();
}

}

// arrayjni.cpp : Defines the exported functions for the DLL application.
//

#include "stdafx.h"
#include "com_example_jni_ArrayJNI.h"
#include <iostream>
/*
* Class:     com_example_jni_ArrayJNI
* Method:    process
* Signature: ([BII)[B
*/
JNIEXPORT jbyteArray JNICALL Java_com_example_jni_ArrayJNI_process
(JNIEnv * env, jobject obj, jbyteArray byteArray) {
jbyte* receivedbyte = env->GetByteArrayElements(byteArray, 0);
jsize size = env->GetArrayLength(byteArray);
printf("(C++) received byte: ");

for (int i = 0; i < size; i++) {
int value = (int)(receivedbyte[i] & 0xff);
printf("%d\t",value);
jbyte v = (~value);

env->SetByteArrayRegion(byteArray, i, 1, &v);
}

return byteArray;

}