在实际的SWT侦听器之外,是否有任何方法可以通过代码忽略侦听器?
例如,我有一个实现SWT文本窗口小部件的Java程序,并且这些小部件有:
-
验证监听器过滤掉不需要的文本输入。
-
modifyListeners等待正确数量的有效输入字符,并自动将focus(使用setfocus())设置为下一个有效字段,跳过选项卡顺序中的其他文本小部件。
-
FocusLost(FocusEvent)FocusListeners,等待文本小部件失去焦点以执行额外的输入验证,并根据用户输入执行SQL查询。
我遇到的问题是清除文本小部件。其中一个小部件的格式为“”(四个数字,一个连字符,然后两个数字),我已经实现了这个监听器,它是SWT代码段的修改版本。
Snippet179
. 此文本小部件的初始文本是“-”以向用户提供预期格式的可视反馈。只有数字是可接受的输入,程序会自动跳过适当点的连字符。
/*
* This listener was adapted from the "verify input in a template (YYYY/MM/DD)" SWT Code
* Snippet (also known as Snippet179), from the Snippets page of the SWT Project.
* SWT Code Snippets can be found at:
* http://www.eclipse.org/swt/snippets/
*/
textBox.addListener(SWT.Verify, new Listener()
{
boolean ignore;
public void handleEvent(Event e)
{
if (ignore) return;
e.doit = false;
StringBuffer buffer = new StringBuffer(e.text);
char[] chars = new char[buffer.length()];
buffer.getChars(0, chars.length, chars, 0);
if (e.character == '\b')
{
for (int i = e.start; i < e.end; i++)
{
switch (i)
{
case 0: /* [x]xxx-xx */
case 1: /* x[x]xx-xx */
case 2: /* xx[x]x-xx */
case 3: /* xxx[x]-xx */
case 5: /* xxxx-[x]x */
case 6: /* xxxx-x[x] */
{
buffer.append(' ');
break;
}
case 4: /* xxxx[-]xx */
{
buffer.append('-');
break;
}
default:
return;
}
}
textBox.setSelection(e.start, e.start + buffer.length());
ignore = true;
textBox.insert(buffer.toString());
ignore = false;
textBox.setSelection(e.start, e.start);
return;
}
int start = e.start;
if (start > 6) return;
int index = 0;
for (int i = 0; i < chars.length; i++)
{
if (start + index == 4)
{
if (chars[i] == '-')
{
index++;
continue;
}
buffer.insert(index++, '-');
}
if (chars[i] < '0' || '9' < chars[i]) return;
index++;
}
String newText = buffer.toString();
int length = newText.length();
textBox.setSelection(e.start, e.start + length);
ignore = true;
textBox.insert(newText);
ignore = false;
/*
* After a valid key press, verifying if the input is completed
* and passing the cursor to the next text box.
*/
if (7 == textBox.getCaretPosition())
{
/*
* Attempting to change the text after receiving a known valid input that has no results (0000-00).
*/
if ("0000-00".equals(textBox.getText()))
{
// "0000-00" is the special "Erase Me" code for these text boxes.
ignore = true;
textBox.setText(" - ");
ignore = false;
}
// Changing focus to a different textBox by using "setFocus()" method.
differentTextBox.setFocus();
}
}
}
);
正如您所看到的,我唯一能从代码的不同点清除这个文本小部件的方法是分配“0000-00”
textBox.setText("000000")
并检查监听器中的输入。当接收到该输入时,侦听器将文本改回“-”(四个空格,一个连字符,然后两个空格)。
还有一个focuslost侦听器解析这个文本小部件中的空格,然后为了避免不必要的SQL查询,如果输入无效(即包含空格),它将清除/重置所有字段。
// Adding focus listener to textBox to wait for loss of focus to perform SQL statement.
textBox.addFocusListener(new FocusAdapter()
{
@Override
public void focusLost(FocusEvent evt)
{
// Get the contents of otherTextBox and textBox. (otherTextBox must be <= textBox)
String boxFour = otherTextBox.getText();
String boxFive = textBox.getText();
// If either text box has spaces in it, don't perform the search.
if (boxFour.contains(" ") || boxFive.contains(" "))
{
// Don't perform SQL statements. Debug statement.
System.out.println("Tray Position input contains spaces. Ignoring.");
//Make all previous results invisible, if any.
labels.setVisible(false);
differentTextBox.setText("");
labelResults.setVisible(false);
}
else
{
//... Perform SQL statement ...
}
}
}
);
好啊。通常,我在代码中使用SWT消息框小部件与用户通信,或者希望在验证输入后将文本小部件更改回空状态。问题是,MessageBox似乎创建了FocusLost事件,并且使用.settext(string)方法受制于SWT。请验证文本小部件上存在的侦听器。
有没有建议在代码中有选择地忽略这些侦听器,但在所有其他用户输入中都保留这些侦听器?
提前感谢您的帮助。
