function loadType(){    $.get(       'getAllTypes.action',      function(data){       var $sel = $("#seldvd");       // console.log(data);       for(var i = 0;i       $item = $(""); //添加option        $item.val(data[i].id); //添加option的value ，数据库中用id和type保存的数据       $item.html(data[i].type); //添加option数据        $sel.append($item); //将option添加进select        }       },'json'      );  } 

 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);//这里导入需要转json数据包 String jsString = arr.toString(); //响应到客户端 request.setCharacterEncoding("utf-8"); response.setContentType("text/plain;charset=utf-8"); response.getWriter().print(jsString); //返回下拉列表需要的json格式数据 } 

 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; } } 

 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("显示所有类型报错："+e.getMessage()); }finally{ super.closeAll(rs, psm, con); } return typeList; // } }