ajaxdao.java

jsp和ajax 的三级联动

package com.soft.dwr;   
  
import java.sql.Connection;   
import java.sql.PreparedStatement;   
import java.sql.ResultSet;   
import java.sql.SQLException;   
import java.util.HashMap;   
import java.util.Map;   
  
public class AjaxDAO {   
  
    private final String COUNTRY = "select * from country";   
    private final String PROVINCE = "select * from province where countryid=?";   
    private final String CITY="select * from city where provinceid=?";   
       
       
    public  Map getProvince(int id) {   
        Map<String, String> map = new HashMap<String, String>();   
        Connection con;   
        try {   
            con = DBConnection.getCon();   
            PreparedStatement ps = con.prepareStatement(PROVINCE);   
            ps.setInt(1, id);   
            ResultSet rs = ps.executeQuery();   
            while (rs.next()) {   
                map.put(new Integer(rs.getInt(1)).toString(), rs.getString(2));   
            }   
                   if(rs!=null){rs.close();}   
                   if(ps!=null){ps.close();}   
        } catch (SQLException e) {   
            // TODO Auto-generated catch block   
            e.printStackTrace();   
        }   
  
        return map;   
  
    }   
  
    public Map getCountry() {   
        Map<String, String> map = new HashMap<String, String>();   
        Connection con;   
        try {   
            con = DBConnection.getCon();     
            PreparedStatement ps = con.prepareStatement(COUNTRY);   
            ResultSet rs = ps.executeQuery();   
            while (rs.next()) {   
                map.put(new Integer(rs.getInt(1)).toString(), rs.getString(2));   
            }   
        } catch (SQLException e) {   
            // TODO Auto-generated catch block   
            e.printStackTrace();   
        }   
  
        return map;   
  
    }   
  
    public  Map getCity(int id) {   
        Map<String, String> map = new HashMap<String, String>();   
        Connection con;   
        try {   
            con = DBConnection.getCon();     
            PreparedStatement ps = con.prepareStatement(CITY);   
            ps.setInt(1, id);   
            ResultSet rs = ps.executeQuery();   
            while (rs.next()) {   
                map.put(new Integer(rs.getInt(1)).toString(), rs.getString(2));   
            }   
        } catch (SQLException e) {   
            // TODO Auto-generated catch block   
            e.printStackTrace();   
        }   
  
        return map;   
  
    }   
}