Exemplo de select apartir de outro select com taglibs

package tags;
import conexao.Conexao;
import java.io.*;
import java.sql.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;

public final class TagClientes implements BodyTag{
	private PageContext pc=null;
	private BodyContent body=null;
	private StringBuffer sb=new StringBuffer();
	private ResultSet rs=null;
	private Conexao con=null;
		
	public void setPageContext(PageContext p){
		pc=p;
	}
	public void setParent(Tag t){}
	public Tag getParent(){
		return null;
	}
	
	public int doStartTag() throws JspException{
		try{
			int tipo=1;
			con=new Conexao();
			rs=con.executeQuery("select codigo,nome from os_colaboradores where tipo="+tipo+" order by codigo");
			setVariaveis();
		}catch(SQLException e){
			System.out.println(e);
		}
		if(pc.getAttribute("codigo")==null)
		return SKIP_BODY;
		
		return EVAL_BODY_BUFFERED;
	}
	public void setBodyContent(BodyContent b){
		body=b;
	}
	public void doInitBody()throws JspException{}
	
	public boolean setVariaveis()throws JspTagException{
		try{
			String cod="";
				if(rs.next()){
				cod=""+rs.getInt("codigo");
				pc.setAttribute("codigo",cod);
				pc.setAttribute("nome",rs.getString("nome"));
				return true;
			}else{
				return false;
			}
		}catch(SQLException e){
			System.out.println(e);
			return false;
		}
	}
	public int doAfterBody() throws JspException{
		try{
			sb.append(body.getString());
			body.clear();
		}catch (IOException e){
			throw new JspException("erro fatal: IOException!");
		}
		if(setVariaveis()){
			return EVAL_BODY_AGAIN;
		}
		try{
			body.getEnclosingWriter().write(sb.toString());
		}catch(IOException e){
			throw new JspException("Erro fatal:IOException!");
		}
		return SKIP_BODY;
	}
	public int doEndTag() throws JspException{
		try{
		body.clear();
		int i=sb.length();
		sb.delete(0,i);
		}catch(IOException e){throw new JspException("erro io");}
		try{
			if(rs!=null){
				rs.close();
				rs=null;
			}
			if(con!=null){
				con.fecharConexao();
				con=null;
			}
		}catch(SQLException e){}
		return EVAL_PAGE;
	}
	public void release(){
		pc=null;
		body=null;
		sb=null;
	}

}

package tags;

import javax.servlet.jsp.tagext.*;

public class TagTEIClientes extends TagExtraInfo{
	
	public VariableInfo[] getVariableInfo(TagData data){
		return new VariableInfo[]{
			new VariableInfo("codigo","java.lang.String",true,VariableInfo.NESTED),
			new VariableInfo("nome","java.lang.String",true,VariableInfo.NESTED),
		};
	}
}

<select name="cliente" id="cliente" onChange="buscaContato(this)">
		<option value="">Selecione o cliente</option>
		<cliente:mostreclientes>
						<option value=<%=codigo%>><%=codigo%>-<%=nome%></option>
		</cliente:mostreclientes>
          </select>

<select name="solicitante" id="select2">
		<option value="">selecione o Contato</option>
		<%
		String cliente=request.getParameter("cliente");
		if(cliente!=null){
			rs=con.executeQuery("select codigo,nome from os_contatos where cliente="+cliente+"order by codigo");
			while(rs.next()){
			int codigo=rs.getInt("codigo");
			String nome=rs.getString("nome");
			System.out.println("tentou");
			%><option value=<%=codigo%>><%=codigo%>-<%=nome%></option>
			<%}
		}
		
		%>
		
          </select>