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jni笔记
2019-11-21

jni与java间的交互

jni获取/修改jobject成员

参考:CSDN

java与c变量转换

JNIEXPORT void JNICALL Java_ClassName_MethodName(JNIEnv *env, jobject obj, jstring javaString)
{
  const char *nativeString = (*env)->GetStringUTFChars(env, javaString, 0);
  (*env)->ReleaseStringUTFChars(env, javaString, nativeString);
}

javaString[]->c

参考:CSDN

public native void sendString(String[] imgPaths);// 函数声明
JNIEXPORT void JNICALL
Java_com_example_stitch_MainActivity_sendString(
    JNIEnv *env,
    jobject thiz,
    jobjectArray imgPaths) {
  // 获取String数组长度
  jsize str_len = env->GetArrayLength(imgPaths);

  for (int i = 0; i < str_len; i ++) {
    jstring tmp = (jstring) env->GetObjectArrayElement(imgPaths, i);
    const char *img_path = env->GetStringUTFChars(tmp, 0);

    LOG("img[%d]: %s", i, img_path);
  }
}

javaMat->cMat

public native void findPoint(String imgPath, long result);// 函数声明

... {// 函数调用
  findPoint(appPath + "/img0.png", matBGR.getNativeObjAddr());
}
extern "C"
JNIEXPORT void JNICALL
Java_com_example_stitch_MainActivity_findPoint(
        JNIEnv *env,
        jobject thiz,
        jstring imgPath,
        jlong result) {
  *(Mat *)result = mat.clone();// 一定要用clone()
  umat.copyTo(*(Mat *)result);
}

jni的opencvmat与javaBitmap互转

参考:简书

jni新建图片返回到java

TODO

参考
stackoverflow

jni调用java类的函数