解析如何开发FineReport的自定义控件

package com.hg.free.plugin.customcombo.param;
import com.fr.design.designer.creator.XComboBox;
import com.fr.design.fun.impl.AbstractParameterWidgetOptionProvider;
import com.fr.form.ui.Widget;
public class WidgetRegister extends AbstractParameterWidgetOptionProvider {
  @Override
  public Class<? extends Widget> classForWidget() {
    return CustomComboBox.class;
  }
  @Override
  public Class<?> appearanceForWidget() {
    return XComboBox.class;
  }
  @Override
  public String iconPathForWidget() {
    return "/com/fr/web/images/combobox.png";
  }
  @Override
  public String nameForWidget() {
    return "自定义下拉框";
  }
}　

package com.hg.free.plugin.customcombo.param;
import com.fr.form.ui.ComboBox;
import com.fr.ui.DataFilter;
public class CustomComboBox extends ComboBox {
  private static final long serialVersionUID = 7169771062153345236L;
  @Override
  public String getXType() {
  return "customcombo";
 }
  @Override
  protected DataFilter createDataFilter() {
  return new CustomComboBoxDataFilter();
 }
}

package com.hg.free.plugin.customcombo.param;
import com.fr.form.ui.ComboBoxDataFilter;
public class CustomComboBoxDataFilter extends ComboBoxDataFilter {
  @Override
  public boolean isMatch(String txt, String filter) {
    if(null==txt && null!=filter)return false;
    if(null==txt && null==filter)return true;
    return txt.indexOf(filter)!=-1;
  }
} 

(function($){
  FR.CustomComboBoxEditor = FR.extend(FR.ComboBoxEditor, {
   _init: function () {
   FR.CustomComboBoxEditor.superclass._init.apply(this, arguments);
   }
  });
  $.shortcut("customcombo", FR.CustomComboBoxEditor);
})(jQuery);