Ajaxがドロップダウンリストに動的にデータを追加

1.フロントjsp、新しいドロップダウンコントロール

         
   2. js  ，   function  ，  ajax，   'getAllTypes.action'  servlet  ，            ，     
   
   
  function loadType(){
 $.get(
  'getAllTypes.action',
  function(data){
  var $sel = $("#seldvd");
  // console.log(data);
  for(var i = 0;i");  //  option
    $item.val(data[i].id);  //  option value ，     id type     
                               
    $item.html(data[i].type); //  option  
    $sel.append($item); // option   select
   }
  },'json'
 );
} 
   
   3.     servlet  ，   Ajax     
   
  public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		request.setCharacterEncoding("utf-8");
		ArrayList typeList = new ArrayList();
		typeDao td = new typeDao();
		
		typeList = td.getAllTypes();
		
		JSONArray arr = new JSONArray(typeList);//       json   
		String jsString = arr.toString();
		
		//      		
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/plain;charset=utf-8");
		response.getWriter().print(jsString); //         json    

		
	} 
   4.       ，         ？      （MySQL）。                   
   
  typeInfo.java 
  
 
  import java.io.Serializable;

public class typeInfo implements Serializable {
	private int id;
	private String type;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	public typeInfo(){
		
	}
	
	public typeInfo(int id, String type) {
		this.id = id;
		this.type = type;
	}
	
	

}
 
  TypeDao.java  (    JDBC ) 
   
   
  import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;

import model.typeInfo;

public class typeDao extends baseDao {
	
	public ArrayList getAllTypes(){
		ArrayList typeList = new ArrayList();
		
		Connection con = null;
		PreparedStatement psm = null;
		ResultSet rs = null;
		
		try {
			con = super.getConnection();
			psm = con.prepareStatement("select * from types");
			rs = psm.executeQuery();
			while(rs.next()){
				typeInfo types = new typeInfo();
				types.setId(rs.getInt(1));
				types.setType(rs.getString(2));
				
				typeList.add(types);
			}
			
		} catch (Exception e) {
			System.out.println("        ："+e.getMessage());
		}finally{
			super.closeAll(rs, psm, con);
		}
		
		
		return typeList;
	//	
	} 
  }4.   ，  Tomcat ，      ，