Android JNI之C/C++层调用JAVA

public class TestNdk{

    int a;//本示例中将被修改的JAVA变量
    Handler handler;

    public TestNdk(Handler handler){
        this.handler = handler;
        setUp();
    }

    public native void setUp();//本地方法

    public native static int getStringFromNative();//本地方法

    public int getA() {
        return a;
    }

    public native void setA(int a);//本地方法

    public void notifyFiledChange(){//本示例中将被C/C++调用的JAVA方法
        Message message = new Message();
        Bundle bundle = new Bundle();
        bundle.putInt("a",a);
        message.setData(bundle);
        message.what=1;
        handler.sendMessage(message);
    }

    static {
        System.loadLibrary("MyJni");//导入生成的链接库文件
    }

}

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_x_mp4player_TestNdk */

#ifndef _Included_com_x_mp4player_TestNdk
#define _Included_com_x_mp4player_TestNdk
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_x_mp4player_TestNdk
 * Method:    setUp
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_x_mp4player_TestNdk_setUp
  (JNIEnv *, jobject);

/*
 * Class:     com_x_mp4player_TestNdk
 * Method:    setA
 * Signature: (I)V
 */
JNIEXPORT void JNICALL Java_com_x_mp4player_TestNdk_setA
        (JNIEnv *env, jobject thiz,jint i);

/*
 * Class:     com_x_mp4player_TestNdk
 * Method:    getStringFromNative
 * Signature: ()I
 */
JNIEXPORT jint JNICALL Java_com_x_mp4player_TestNdk_getStringFromNative
  (JNIEnv *, jclass);

#ifdef __cplusplus
}
#endif
#endif

#include <jni.h>
#include <com_x_mp4player_TestNdk.h>

jobject m_object;
jmethodID m_mid;
jfieldID m_fid;

JNIEXPORT jint JNICALL Java_com_x_mp4player_TestNdk_getStringFromNative
        (JNIEnv *env, jclass cls) {
    return 1;
}

JNIEXPORT void JNICALL Java_com_x_mp4player_TestNdk_setUp
        (JNIEnv *env, jobject thiz) {
    jclass clazz = (*env).GetObjectClass(thiz);//获取该对象的类
    m_object = (*env).NewGlobalRef(thiz);//创建对象的本地变量
    m_mid =(*env).GetMethodID(clazz, "notifyFiledChange", "()V");//获取JAVA方法的ID
    m_fid = (*env).GetFieldID(clazz,"a","I");//获取java变量的ID
    return;
}

JNIEXPORT void JNICALL Java_com_x_mp4player_TestNdk_setA
        (JNIEnv *env, jobject thiz,jint i) {
    (*env).SetIntField( m_object, m_fid,i);
    (*env).CallVoidMethod(m_object,m_mid);
    return;
}

JNIEXPORT void JNICALL Java_com_x_mp4player_TestNdk_setUp
        (JNIEnv *env, jobject thiz) {
    ...
    jclass clazz = (*env).GetObjectClass(thiz);//获取该对象的类
    ...
    return;
}

JNIEXPORT void JNICALL JAVA_nativeMethod
        (JNIEnv *env, jobject thiz,jint i){
    ...
    jclass clazz = (*env).GetObjectClass(thiz);
    jmethodID mid = (*env).GetMethodID(clazz,"<init>","()V");
    jobject obj = (*env).NewObject(clazz,mid);
    ...
    return;
}

JNIEXPORT void JNICALL JAVA_nativeMethod
        (JNIEnv *env, jobject thiz,jint i){
    ...
    jclass clazz = (*env).FindClass("com/x/test/Test");//参数为类路径
    jmethodID mid = (*env).GetMethodID(clazz,"<init>","()V");
    jobject obj = (*env).NewObject(clazz,mid);
    ...
    return;
}