JSP+AJAX实现两级select联动 代码

package test; import java.beans.Statement; import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class test { static String server="localhost"; //MYSQL 服务器的地址 static String dbname="cww"; //MYSQL 数据库的名字 static String dbuser="root"; //MYSQL 数据库的登录用户名 static String dbpass="admin"; //MYSQL 数据库的登录密码 static String dbport="3306"; //SQL Server 服务器的端口号，默认为1433 //数据库连接字符串 static String url ="jdbc:mysql://"+server+":"+dbport+"/"+dbname+"?user="+dbuser+"&password="+dbpass+"&useUnicode=true&characterEncoding=utf-8"; static Connection conn=null; public static void add_qd(){ try { Class.forName("com.mysql.jdbc.Driver"); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); }//建立连接 } public static Connection getConn(){ try { add_qd(); conn=DriverManager.getConnection(url); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return conn; } public void test(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=gbk"); PrintWriter out = response.getWriter(); //out.print("交流空间地方撒"); String dl_id=request.getParameter("dl"); out.print(dl_id); Connection con=getConn(); java.sql.Statement stmt; try { stmt = con.createStatement(); if(dl_id!=null&&!dl_id.equals("")){ out.print("<select name='subject' style='font-size: 9pt'>"); ResultSet rs=stmt.executeQuery("select * from splb where splb_dl='"+dl_id+"'"); try { if(!rs.next()){ out.print("<option value=>请增加类别</option>");} else{ rs.previous(); while(rs.next()){ int splb_id=rs.getInt(1); String sort_name=rs.getString(2); out.print("<option value='" +splb_id+"'>" +sort_name+ "</option>"); } } rs.close(); stmt.close(); con.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }catch (SQLException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } out.print(" </select> "); } }