#include #include#include#include

#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "native-activity", __VA_ARGS__))

#define LOGII(...) ((void)__android_log_print(ANDROID_LOG_INFO, "the int value is : %d", __VA_ARGS__))JNIEXPORTvoidJNICALL

Java_com_ndk_NDKFirstActivity_acessField(JNIEnv*env , jobject obj)

{

jfieldID fid;

jstring jstr;const char*str;/**从对象中回去类*/jclass cls= (*env)->GetObjectClass(env ,obj);/**根据类、字段、和字段类型获取字段id*/fid= (*env)->GetFieldID(env ,cls,"str" ,"Ljava/lang/String;");//类型后面的分号不能省略

if(fid ==NULL)

{return;

}/**根据字段ID 和对象 获取值*/jstr= (*env)->GetObjectField(env ,obj,fid);

str= (*env)->GetStringUTFChars(env ,jstr ,NULL);if(str ==NULL)

{return;

}

LOGI(str);

(*env)->ReleaseStringUTFChars(env ,jstr,str);

jstr= (*env)->NewStringUTF(env ,"I reset the str value in native c,and success");if(jstr ==NULL)

{return;

}/**根据对象、字段id 设置值*/(*env)->SetObjectField(env ,obj , fid , jstr);

}

JNIEXPORTvoidJNICALL

Java_com_ndk_NDKFirstActivity_accessStaticField(JNIEnv*env ,jobject obj)

{

jfieldID fid ;

jint si;

jclass cls= (*env)->GetObjectClass(env , obj);

fid= (*env)->GetStaticFieldID(env ,cls ,"value","I");if(fid==NULL)

{return;

}

//根据类，设置静态字段值

si= (*env)->GetStaticIntField(env ,cls ,fid);//LOGI(si+"");

(*env)->SetStaticIntField(env ,cls ,fid ,2012);

}

JNIEXPORTvoidJNICALL

Java_com_ndk_NDKFirstActivity_invokeMethod(JNIEnv*env ,jobject obj)

{

jclass cls= (*env)->GetObjectClass(env ,obj);

jmethodID mid= (*env)->GetMethodID(env ,cls ,"callback","()V");if(mid ==NULL)

{return;

}

//更加对象、方法字段，调用 Java 方法

LOGI("i invoke callback in native c");

(*env)->CallVoidMethod(env ,obj ,mid);

}

JNIEXPORTvoidJNICALL

Java_com_ndk_NDKFirstActivity_invokeStaticMethod(JNIEnv*env , jobject obj)

{

jclass cls= (*env)->GetObjectClass(env , obj);

jmethodID mid=(*env)->GetStaticMethodID(env ,cls,"staticCallback","(I)V");if(mid ==NULL)

{return;

}

LOGI("i invoke staticCallback in native c");

jint ji= 1000;

//根据类，方法字段，调用静态方法

(*env)->CallStaticVoidMethod(env,cls,mid ,ji);

}

JNIEXPORT jobject JNICALL

Java_com_ndk_NDKFirstActivity_getData(JNIEnv*env , jobject obj , jint ji)

{

//根据类名，获取类

jclass dataClass= (*env)->FindClass(env ,"com/ndk/Data");if(dataClass ==NULL)

{return;

}

//根据类 获取方法字段

jmethodID cid= (*env)->GetMethodID(env ,dataClass ,"" ,"(I)V");if(cid==NULL)

{return;

}

LOGI("i init and return a construct in native c");

//根据类、 构造方法字段 初始化 类对象return (*env)->NewObject(env ,dataClass ,cid , ji);

}