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因此，我为我的应用程序编写了一个 TransferHandler（沿着 Oracle 站点的示例），但是当我尝试移动数据时它并没有移动。它所做的只是将索引处的数据（n-1 即如果我正在移动并将项目移动到 n 位置）到索引 n。您能否检查一下出了什么问题，尽管我尝试了很多选择，但没有一个对我有用。

import javax.swing.TransferHandler;
import javax.swing.*;
import java.awt.datatransfer.*;

    public class ListTransferHandler extends TransferHandler {
        private int[] indices = null;
        private int addIndex = -1; //Location where items were added
        private int addCount = 0;  //Number of items added.

        public boolean canImport(TransferHandler.TransferSupport info) {
            // Check for String flavor
            if (!info.isDataFlavorSupported(DataFlavor.stringFlavor)) {
                return false;
            }
            return true;
        }

        protected Transferable createTransferable(JComponent c) {
            return new StringSelection(exportString(c));
        }

        public int getSourceActions(JComponent c) {
            return TransferHandler.MOVE;
        }

        public boolean importData(TransferHandler.TransferSupport info) {
            if (!info.isDrop()) {
                return false;
            }

            JList list = (JList)info.getComponent();
            DefaultListModel listModel = (DefaultListModel)list.getModel();
            JList.DropLocation dl = (JList.DropLocation)info.getDropLocation();
            int index = dl.getIndex();
            boolean insert = dl.isInsert();

            // Get the string that is being dropped.
            Transferable t = info.getTransferable();
            String data;
            try {
                data = (String)t.getTransferData(DataFlavor.stringFlavor);
            } 
            catch (Exception e) { return false; }

            // Perform the actual import.  
            if (insert) {
                listModel.add(index, data);
            } else {
                listModel.set(index, data);
            }
            return true;
        }

        protected void exportDone(JComponent c, Transferable data, int action) {
            cleanup(c, action == TransferHandler.MOVE);
        }

        //Bundle up the selected items in the list
        //as a single string, for export.
        protected String exportString(JComponent c) {
            JList list = (JList)c;
            indices = list.getSelectedIndices();
            Object[] values = list.getSelectedValues();

            StringBuffer buff = new StringBuffer();

            for (int i = 0; i < values.length; i++) {
                Object val = values[i];
                buff.append(val == null ? "" : val.toString());
                if (i != values.length - 1) {
                    buff.append("\n");
                }
            }

            return buff.toString();
        }

        //Take the incoming string and wherever there is a
        //newline, break it into a separate item in the list.
        protected void importString(JComponent c, String str) {
            JList target = (JList)c;
            DefaultListModel listModel = (DefaultListModel)target.getModel();
            int index = target.getSelectedIndex();

            //Prevent the user from dropping data back on itself.
            //For example, if the user is moving items #4,#5,#6 and #7 and
            //attempts to insert the items after item #5, this would
            //be problematic when removing the original items.
            //So this is not allowed.
            if (indices != null && index >= indices[0] - 1 &&
                  index <= indices[indices.length - 1]) {
                indices = null;
                return;
            }

            int max = listModel.getSize();
            if (index < 0) {
                index = max;
            } else {
                index++;
                if (index > max) {
                    index = max;
                }
            }
            addIndex = index;
            String[] values = str.split("\n");
            addCount = values.length;
            for (int i = 0; i < values.length; i++) {
                listModel.add(index++, values[i]);
            }
        }

        //If the remove argument is true, the drop has been
        //successful and it's time to remove the selected items 
        //from the list. If the remove argument is false, it
        //was a Copy operation and the original list is left
        //intact.
        protected void cleanup(JComponent c, boolean remove) {
            if (remove && indices != null) {
                JList source = (JList)c;
                DefaultListModel model  = (DefaultListModel)source.getModel();
                //If we are moving items around in the same list, we
                //need to adjust the indices accordingly, since those
                //after the insertion point have moved.
                if (addCount > 0) {
                    for (int i = 0; i < indices.length; i++) {
                        if (indices[i] > addIndex) {
                            indices[i] += addCount;
                        }
                    }
                }
                for (int i = indices.length - 1; i >= 0; i--) {
                    model.remove(indices[i]);
                }
            }
            indices = null;
            addCount = 0;
            addIndex = -1;
        }
}
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1 回答 1

2

成功完成导出后，您需要从源中“删除”数据。

为此，您需要重写该TransferHandler.exportDone方法。

protected void exportDone(JComponent source, Transferable data, int action)

数据导出后调用。如果操作是 MOVE，则此方法应删除传输的数据。

由于 MOVE 不是此实现的受支持操作（getSourceActions 不包括 MOVE），因此此方法被实现为不执行任何操作。

基本上，您需要从那里检查action类型并确保目标组件已接受MOVE而不是简单地COPY'ed 它并从源列表中删除元素。

于 2012-09-24T23:22:35.017 回答