I code currently a minecraft java plugin which loads a texturepack but I have a problem. When you decline the download of the texturepack, it will never ask again for downloading or accepting and I never got a error.
I used this code:
player.setResourcepack("<url>");
and it showed one time so it does work but never ask again if I decline it. Please help.
Yes, this is expected behavior. If a player decline resourcepack installation once then he will never receive an installation request again.
Try to provide a new version of the texture pack or rename the texture pack. As a result the players should receive a new request.
You can send packages and listen to the responses. There are many ways to do so. Essentially, you have to send a PacketPlayOutResourcePackSend packet with the necessary information.
Afterwards, listen to the PacketPlayInResourcePackStatus. There are just a few possible states: SUCCESSFULLY_LOADED, DECLINED, FAILED_DOWNLOAD, ACCEPTED. In theory, you have to resend the package request once the state is DECLINED. (Like my credit card -.-)
I can't give you any more details since I haven't used this in a while, but no one else seemed to answer your question.