#include<stdio.h>

#include "jniZ_TjniField.h"

JNIEXPORT void JNICALL Java_jniZ_TjniField_NativeFunc(JNIEnv * env, jobject obj)

{

    // 获取obj中对象的class对象

    jclass clazz = env->GetObjectClass(obj);

    // 获取 类属性字段的id(最后一个参数是 属性字段 的签名)

    jfieldID fieldidFi = env->GetFieldID(clazz, "Fi", "I");            // public

    jfieldID fieldidFj = env->GetFieldID(clazz, "Fj", "I");            // protected

    jfieldID fieldidFk = env->GetFieldID(clazz, "Fk", "I");            // private

    jfieldID fieldidFm = env->GetStaticFieldID(clazz, "Fm", "I");    // (非public/protected/private)的static

    // 获取 类属性字段的值

    jint i = env->GetIntField(obj, fieldidFi);

    jint j = env->GetIntField(obj, fieldidFj);

    jint k = env->GetIntField(obj, fieldidFk);

    jint m = env->GetStaticIntField(clazz, fieldidFm);

    printf("i : %d\n", i);

    printf("j : %d\n", j);

    printf("k : %d\n", k);

    printf("m : %d\n", m);

    // 修改number的值为100，这里要注意的是jint对应C++是long型 ∴后面要加一个"L"

    env->SetIntField(obj, fieldidFi,  + i);

    env->SetIntField(obj, fieldidFj,  + j);

    env->SetIntField(obj, fieldidFk,  + k);

    env->SetStaticIntField(clazz, fieldidFm,  + m);

}

package jniZ;

import java.lang.reflect.Field;

public class TjniField

{

    public int Fi = 0;

    protected int Fj = 1;

    private int Fk = 2;

    static int Fm = 3;

    public native void NativeFunc();

    public static void main(String[] args) throws Exception

    {

        //调用动态链接库

        System.loadLibrary("JniField_VC6");

        TjniField jniZ = new TjniField();

        jniZ.NativeFunc();

        // (1)、i

        System.out.println("Java Fi : "+jniZ.Fi);

        // (2)、j

        Class<?> clazz = jniZ.getClass();

        Field fieldJ = clazz.getDeclaredField("Fj");

        fieldJ.setAccessible(true);

        int j = fieldJ.getInt(jniZ);

        System.out.println("Java Fj : "+j);

        // (3)、k

        Field fieldK = clazz.getDeclaredField("Fk");

        fieldK.setAccessible(true);

        int k = fieldK.getInt(jniZ);

        System.out.println("Java Fk : "+k);

        // (4)、m

        System.out.println("Java Fm : "+Fm);

    }

}

Java Fi : 100

Java Fj : 101

Java Fk : 102

Java Fm : 103

i : 0

j : 1

k : 2

m : 3