package com.yuneec.demo;public class Person {static {System.loadLibrary("td");}public int age = 20;public native void readAge();public int getAge() {return age;}}

package com.yongdaimi.android.framework;import com.yuneec.demo.Person;import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;public class MainActivity extends Activity implements OnClickListener{private Button bt_test;private Person person;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);bt_test = (Button) findViewById(R.id.bt_test);bt_test.setOnClickListener(this);person = new Person();}@Overridepublic void onClick(View v) {switch (v.getId()) {case R.id.bt_test:// called by native
            person.readAge();// called by javaint java_age = person.getAge();Log.i("xp.chen", "java_age is: "+java_age);break;default:break;}}}

#ifdef __ANDROID__#include <jni.h>
#include <android/log.h>
#include <stdio.h>
#include "jnihelp.h"#define LOG_TAG "xp.chen"#ifdef LOG_TAG#define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
#else#define LOGE(...)
#endifJNIEXPORT void com_yuneec_demo_Person_readAge(JNIEnv *env, jobject obj)
{//获致obj中对象的classjclass clazz = (*env)->GetObjectClass(env, obj);// 获取java中age字段的ID(最后一个参数是age的签名)jfieldID id_age = (*env)->GetFieldID(env, clazz, "age", "I");// 获取age字段对应的值jint age = (*env)->GetIntField(env, obj, id_age);// 输出// printf("current age is: %d\n", number);LOGE("native-age is: %d\n", age);// 重新修改age字段的值为100。(*env)->SetIntField(env, obj, id_age, 100);
}static JNINativeMethod methods[] = {{"readAge","()V",(void*)com_yuneec_demo_Person_readAge},
};static const char *classPathName = "com/yuneec/demo/Person";static int registerNativeMethods(JNIEnv* env, const char* className,JNINativeMethod* gMethods, int numMethods)
{jclass clazz;clazz = (*env)->FindClass(env, className);if (clazz == NULL){return JNI_FALSE;}if ((*env)->RegisterNatives(env, clazz, gMethods, numMethods) < 0){return JNI_FALSE;}return JNI_TRUE;
}void JNI_OnUnload(JavaVM* vm, void* reserved)
{return;
}jint JNI_OnLoad(JavaVM* vm, void* reserved)
{JNIEnv *env;if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) {return -1;}if (JNI_TRUE != registerNativeMethods(env, classPathName,methods, sizeof(methods) / sizeof(methods[0]))){return -1;}return JNI_VERSION_1_4;
}
#endif