ItemTransferListener.java 文件源码

@EventHandler
public void onPlayerPickupItem(PlayerPickupItemEvent event) {
    // When this event is fired, the ItemStack in the Item being picked up is temporarily
    // set to the amount that will actually be picked up, while the difference from the
    // actual amount in the stack is available from getRemaining(). When the event returns,
    // the original amount is restored to the stack, meaning that we can't change the amount
    // from inside the event, so instead we replace the entire stack.

    int initialQuantity = event.getItem().getItemStack().getAmount();
    PlayerItemTransferEvent transferEvent = new PlayerItemTransferEvent(
        event, ItemTransferEvent.Type.PICKUP, event.getPlayer(),
        Optional.empty(),
        Optional.of(new InventorySlot<>(event.getPlayer().getInventory())),
        event.getItem().getItemStack(), event.getItem(),
        initialQuantity, event.getPlayer().getOpenInventory().getCursor()
    );

    this.callEvent(transferEvent);

    int quantity = Math.min(transferEvent.getQuantity(), initialQuantity);

    if(!event.isCancelled() && quantity < initialQuantity) {
        event.setCancelled(true);
        if(quantity > 0) {
            ItemStack stack = event.getItem().getItemStack().clone();
            stack.setAmount(stack.getAmount() - quantity);
            event.getItem().setItemStack(stack);

            stack = stack.clone();
            stack.setAmount(quantity);
            event.getPlayer().getInventory().addItem(stack);
            event.getPlayer().playSound(event.getPlayer().getLocation(), Sound.ENTITY_ITEM_PICKUP, 1, 1);
        }
    }
}