java - Java / Java EE

clubBoard 表的字段
public class ClubBoard implements java.io.Serializable {

// Fields

/**
* 
*/
private static final long serialVersionUID = 8452179022803201281L;

private Integer BId;

private Company company;

private String BName;

private Set clubSections = new HashSet(0);

clubSection 表的字段
public class ClubSection implements java.io.Serializable {

// Fields

/**
* 
*/
private static final long serialVersionUID = -2340580957701774443L;

private Integer SId;

private ClubBoard clubBoard;

private String SName;

private Integer SClickCount;

private Integer STopicCount;

private Set clubTopics = new HashSet(0);


JSP页面如何获取第1个下拉框里面的值，在第2个下拉框里面获取到
  <select id="clubBoard" name="clubBoard" onChange="showCS(this.value)">
<option value=0>---请选择---</option>
<%
for(ClubBoard clubBoard:clubBoardList){
out.print("<option value='"+clubBoard.getBId()+"'>"+clubBoard.getBName() +"</option>");
}
%>
</select>
<select name="clubSection" id="clubSection">
<option value=1>---请选择---<