MyReader JAVA记事本（三）剪切复制粘贴删除取消

1.取消操作

private UndoManager undomg = new UndoManager();
if(undomg.canUndo()) { //撤销     undomg.undo();}

2.复制，剪切，粘帖，删除操作

if("剪切(T)".equals(actStr)){
            String temp = myJta.getSelectedText(); // 选取文本
            StringSelection text = new StringSelection(temp);
            clipboard.setContents(text, null);
            int start = myJta.getSelectionStart();
            int end = myJta.getSelectionEnd();
            myJta.replaceRange("", start, end); // 删除被选取的文本
        }
        if("复制(C)".equals(actStr)){
            String temp = myJta.getSelectedText(); // 选取文本
            StringSelection text = new StringSelection(temp);
            clipboard.setContents(text, null);
        }
        if("粘贴(P)".equals(actStr)) {
            Transferable contents = clipboard.getContents(this);
            DataFlavor flavor = DataFlavor.stringFlavor;
            if (contents.isDataFlavorSupported(flavor)){
                try {
                    String str;
                    str = (String) contents.getTransferData(flavor);
                    myJta.append(str);
                } catch (Exception ee) {
                    ee.printStackTrace();
                }
            }
        }
        if("删除(D)".equals(actStr)){
            int start = myJta.getSelectionStart();
            int end = myJta.getSelectionEnd();
            myJta.replaceRange("", start, end); // 删除被选取的文本。
        }