[英]C++: Traverse DBUS message to find BlueZ 5 adapter using iterator
我正在尝试使用BlueZ 5更新的Dbus API查找可用的蓝牙适配器。
与BlueZ 4完全有一个方法(即org.bluez.Manager.FindAdapter())不同,BlueZ 5将FreeDesktop ObjectManager接口与GetManagedObjects()方法一起使用。 此方法返回大量结果:
array [
dict entry(
object path "/org/bluez"
array [
dict entry(
string "org.freedesktop.DBus.Introspectable"
array [
]
)
dict entry(
string "org.bluez.AgentManager1"
array [
]
)
dict entry(
string "org.bluez.ProfileManager1"
array [
]
)
]
)
dict entry(
object path "/org/bluez/hci0"
array [
dict entry(
string "org.freedesktop.DBus.Introspectable"
array [
]
)
dict entry(
string "org.bluez.Adapter1"
array [
dict entry(
string "Address"
variant string "XX:XX:XX:XX:XX:XX"
)
dict entry(
string "Name"
variant string "My_Adapter"
)
dict entry(
string "Alias"
variant string "kubuntu-0"
)
dict entry(
string "Class"
variant uint32 0
)
dict entry(
string "Powered"
variant boolean false
)
dict entry(
string "Discoverable"
variant boolean true
)
dict entry(
string "DiscoverableTimeout"
variant uint32 0
)
dict entry(
string "Pairable"
variant boolean true
)
dict entry(
string "PairableTimeout"
variant uint32 0
)
dict entry(
string "Discovering"
variant boolean false
)
dict entry(
string "UUIDs"
variant array [
string "00001200-0000-1000-8000-00805f9b34fb"
string "00001800-0000-1000-8000-00805f9b34fb"
string "00001801-0000-1000-8000-00805f9b34fb"
string "0000110e-0000-1000-8000-00805f9b34fb"
string "0000110c-0000-1000-8000-00805f9b34fb"
]
)
dict entry(
string "Modalias"
variant string "usb:sdfasdfsadf"
)
]
)
dict entry(
string "org.freedesktop.DBus.Properties"
array [
]
)
dict entry(
string "org.bluez.Media1"
array [
]
)
dict entry(
string "org.bluez.NetworkServer1"
array [
]
)
]
)
.
.etc.
. ]
BlueZ 5 API简介和移植指南说:“ 默认适配器的概念总是有点模糊,无法更改其值,因此,如果应用程序需要类似的东西,则可以例如选择它们遇到的第一个适配器。 GetManagedObjects答复。 ”
我已经使用迭代器编写了C ++代码来做到这一点(我没有使用Python的经验),但是对于看起来如此简单的东西却真的很久了:
if (dbus_message_iter_init(reply, &rootIter) && //point iterator to reply message
DBUS_TYPE_ARRAY == dbus_message_iter_get_arg_type(&rootIter)) //get the type of message that iter points to
{
debug_print("Type Array.\n");
DBusMessageIter arrayElementIter;
dbus_message_iter_recurse(&rootIter, &arrayElementIter); //assign new iterator to first element of array
debug_print("-->Descending into Array (recursing).\n");
while(!adapterFound){
if (DBUS_TYPE_DICT_ENTRY == dbus_message_iter_get_arg_type(&arrayElementIter))
{
debug_print(" Type Dict_Entry.\n");
DBusMessageIter dictEntryIter;
dbus_message_iter_recurse(&arrayElementIter,&dictEntryIter ); //assign new iterator to first element of
debug_print(" -->Descending into Dict_Entry (recursing).\n");
if (DBUS_TYPE_OBJECT_PATH == dbus_message_iter_get_arg_type(&dictEntryIter))
{
debug_print(" Type DBUS_TYPE_OBJECT_PATH.\n");
dbus_message_iter_get_basic(&dictEntryIter, &adapter_path);
if(device && strstr(adapter_path,device))
{
adapterFound = TRUE;
debug_print(" Adapter %s FOUND!\n",device);
}
}
dbus_message_iter_next(&dictEntryIter);
if (DBUS_TYPE_ARRAY == dbus_message_iter_get_arg_type(&dictEntryIter))
{
debug_print(" Type DBUS_TYPE_ARRAY.\n");
DBusMessageIter innerArrayIter;
dbus_message_iter_recurse(&dictEntryIter, &innerArrayIter);
dbus_message_iter_next(&innerArrayIter);
debug_print(" -->Descending into Array (recursing).\n");
if (DBUS_TYPE_DICT_ENTRY == dbus_message_iter_get_arg_type(&innerArrayIter))
{
debug_print(" Type Dict_Entry.\n");
DBusMessageIter innerDictEntryIter;
dbus_message_iter_recurse(&innerArrayIter,&innerDictEntryIter ); //assign new iterator to first element of
debug_print(" -->Descending into Dict_Entry (recursing).\n");
if (DBUS_TYPE_STRING == dbus_message_iter_get_arg_type(&innerDictEntryIter))
{
debug_print(" Type DBUS_TYPE_STRING.\n");
char *dbusObject;
dbus_message_iter_get_basic(&innerDictEntryIter, &dbusObject);
debug_print(" This is an object of type:%s.\n", dbusObject);
if(strncmp(dbusObject,adapterString,strCmpLimit))
debug_print(" Not an adapter.\n");
else{
if(!device)
{
debug_print(" No adapter given, so using first available: %s\n", adapter_path);
adapterFound = TRUE;
}
debug_print(" Adapter.\n");
}
}
debug_print(" <--Ascending from Dict_Entry.\n");
}
debug_print(" <--Ascending from Array (top layer).\n");
//dbus_message_iter_get_basic(&dictEntryIter, &adapter_path);
}
debug_print(" <--Ascending from Dict_Entry.\n");
}
debug_print("<--Ascending from Array (top layer).\n");
if(!dbus_message_iter_has_next(&arrayElementIter)) break; //check to see if end of array
else dbus_message_iter_next(&arrayElementIter);
}//while loop end --used to traverse array
} //end if - outer arrray
else return 0;
换句话说,我必须为树的每个分支定义一个新的迭代器,以便每次都找到位于固定位置的字符串。 (array [x]-> secondfield [2]-> firstfieldstring)我的问题(最后,我知道)是有人可以指出一种更优雅/更快的解决方案吗?
您可以使用应该由BLuez 5 Adapter对象实现的org.freedesktop.DBus.Properties接口来获取适配器属性。
据我所知,您仍然需要遍历Array直到找到适配器对象路径,但是从那里开始,您可以执行以下操作:
DBusMessage *msg = dbus_message_new_method_call(
"org.bluez",
adapter_object_path,
"org.freedesktop.DBus.Properties", "Get");
const char *property = "Powered"; // (e.g.)
dbus_message_append_args(msg,
DBUS_TYPE_STRING, &property,
DBUS_TYPE_INVALID);
//...
这样,您可以只在数组中查找适配器对象路径,而忽略其余所有内容。 通过此对象路径,您可以请求所需的属性和/或开始发送方法调用。
我不确定是否可以认为这更“优雅”,并且可能不会更快,因为我认为额外的方法调用将比数组遍历慢。 它应该/可以减少代码量,但使其更具可读性...
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