导出方法

The first set of methods we will examine are used for exporting data from a component. These methods are invoked for the drag gesture, or the cut/copy action, when the component in question is the source of the operation. The TransferHandler methods for exporting data are:

• getSourceActions(JComponent)—This method is used to query what actions are supported by the source component, such as COPY, MOVE, or LINK, in any combination. For example, a customer list might not support moving a customer name out of the list, but it would very likely support copying the customer name. Most of our examples support both COPY and MOVE.
• createTransferable(JComponent)—This method bundles up the data to be exported into a Transferable object in preparation for the transfer.
• exportDone(JComponent, Transferable, int)—This method is invoked after the export is complete. When the action is a MOVE, the data needs to be removed from the source after the transfer is complete — this method is where any necessary cleanup occurs.

Sample Export Methods

Here are some sample implementations of the export methods:

int getSourceActions(JComponent c) {
    return COPY_OR_MOVE;
}

Transferable createTransferable(JComponent c) {
    return new StringSelection(c.getSelection());
}

void exportDone(JComponent c, Transferable t, int action) {
    if (action == MOVE) {
        c.removeSelection();
    }
}

Next we will look at the TransferHandler methods required for data import.