在GWT中单击ESCAPE(ESC)时关闭Dialogbox

import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.logical.shared.CloseEvent;
import com.google.gwt.event.logical.shared.CloseHandler;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.Event.NativePreviewEvent;
import com.google.gwt.user.client.Event.NativePreviewHandler;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.RootPanel;

public class CustomDialogBox extends DialogBox {

  public CustomDialogBox() {
    // 设置对话框的标题和内容
    setText("Custom DialogBox");
    setWidget(new HTML("This is a custom DialogBox."));

    // 添加ESC键关闭事件处理器
    addCloseHandler(new CloseHandler<PopupPanel>() {
      @Override
      public void onClose(CloseEvent<PopupPanel> event) {
        // 在对话框关闭时移除ESC键事件处理器
        removeEscapeKeyHandler();
      }
    });
  }

  @Override
  protected void onPreviewNativeEvent(NativePreviewEvent event) {
    super.onPreviewNativeEvent(event);

    // 判断是否按下了ESC键
    if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_ESCAPE) {
      // 关闭对话框
      hide();
    }
  }

  // 添加ESC键事件处理器
  private HandlerRegistration escapeKeyHandler;

  private void addEscapeKeyHandler() {
    escapeKeyHandler = RootPanel.get().addNativePreviewHandler(new NativePreviewHandler() {
      @Override
      public void onPreviewNativeEvent(NativePreviewEvent event) {
        if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_ESCAPE) {
          // 关闭对话框
          hide();
        }
      }
    });
  }

  // 移除ESC键事件处理器
  private void removeEscapeKeyHandler() {
    if (escapeKeyHandler != null) {
      escapeKeyHandler.removeHandler();
      escapeKeyHandler = null;
    }
  }
}