jclass envcls = env->FindClass("android/os/Environment"); //獲得類引用 if (envcls == nullptr) return 0;  //找到對應的類，該類是靜態的返回值是File jmethodID id = env->GetStaticMethodID(envcls, "getExternalStorageDirectory", "()Ljava/io/File;");  //調用上述id獲得的方法，返回對象即File file=Enviroment.getExternalStorageDirectory() //其實就是通過Enviroment調用 getExternalStorageDirectory() jobject fileObj = env->CallStaticObjectMethod(envcls,id,"");  //通過上述方法返回的對象創建一個引用即File對象 jclass flieClass = env->GetObjectClass(fileObj); //或得類引用 //在調用File對象的getPath()方法獲取該方法的ID，返回值為String 參數為空 jmethodID getpathId = env->GetMethodID(flieClass, "getPath", "()Ljava/lang/String;"); //調用該方法及最終獲得存儲卡的根目錄 jstring pathStr = (jstring)env->CallObjectMethod(fileObj,getpathId,"");  path = env->GetStringUTFChars(pathStr,NULL);