jsp

jsp自定义控件：下拉列表，判断从数据库读入的值是否与列表中的某个值相等

第一个：Java类
package com.slei.util;
import com.slei.util.DBConnect;
import com.slei.util.Format;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Vector;
import java.util.Iterator;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.JspException;
import java.io.*;

public class SelecShowtBean extends TagSupport {
       DBConnect dbc = null;
      private Statement stmt;
      private ResultSet rs;
      Format format=null;
      private String idNum;//每页显示几条纪录
      public int doStartTag()throws JspException {

           Vector vc = new Vector();
           vc = this.getAllCityNameInfo();
           Iterator it = vc.iterator();
           JspWriter out=this.pageContext.getOut();
           while (it.hasNext()) {
                SelectShowForm zsi = new SelectShowForm();
                zsi = (SelectShowForm) it.next();
                String id = zsi.getIdNum();
                String name = zsi.getValueZ();
                System.out.println(id + " " + name);
               try {
                   if(idNum.equals(id)){ //判断从数据库读入的值是否与列表中的某个值相等
                    out.println("<option value=" + id + " selected>" + name + "</option>");
                   }else{
                    out.println("<option value=" + id + ">" + name + "</option>");
                   }

               } catch (IOException ex) {
                    ex.printStackTrace(System.out);
               }
            }
           return super.doStartTag();
}
        public void setIdNum(String jumpPage) {
            this.idNum = jumpPage;
        }
        public String getIdNum() {
            return idNum;
       }

      public Vector getAllCityNameInfo()
      {
          Vector vc=new Vector();
          String sql="select * from listcity";
          try {
              dbc=new DBConnect();
               rs=dbc.executeQuery(this.inToStr(sql));
               while(rs.next()) {
                   SelectShowForm rf=new SelectShowForm();
                   rf.setIdNum(this.inToStr(rs.getString("idNum")));
                   rf.setValueZ(this.inToStr(rs.getString("valueZ")));
                   vc.add(rf);
               }

        } catch (Exception e) {

            System.err.println(e.getMessage());
            e.printStackTrace();
        }finally {

            try {
                if (rs != null) {

                   dbc.close();
                }
            } catch (Exception ex1) {
                ex1.printStackTrace(System.out);
            }
        }
          return vc;
      }

      public String inToStr(String str){
          if (str == null) {
              str = "";
          } else {
              try {
                  str = str.replace('\'', (char) 1).trim();
              } catch (Exception e) {
                  System.out.println("inStr");
                  System.out.println(e.getMessage());
              }
          }
          return str;
      }
}

第二：配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">
<taglib>
<tlibversion>1.0</tlibversion>
<jspversion>1.1</jspversion>
<shortname>table</shortname>
     <tag>
     <name>SelecShowtBean</name>
                   <tagclass>com.slei.util.SelecShowtBean</tagclass>
     <attribute>
      <name>idNum</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
     </attribute>
</tag>
</taglib>
第三：jsp页面
<%@taglib uri="/WEB-INF/Tag.tld" prefix="xxx"%>
<select name="jobaddress" id="jobaddress">
         <xxx:SelecShowtBean idNum="<%=(String)hstable.get("jobaddress")%>"></xxx:SelecShowtBean>
</select>

http://hi.baidu.com/sleinet/item/fc5caf2d3d3c2c0e72863e2e