使用easyui从servlet传递json数据到前端页面的两种方

//重写doGet方法
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
​
  request.setCharacterEncoding("UTF-8");//防止request请求时中文数据出现乱码
  String flag = request.getParameter("flag");//通过flag值判定增删改查操作
  if(flag == null) {
    queryOffer(request,response);
  }else if("add".equals(flag)){
    addOffer(request,response);
  }else if("del".equals(flag)) {
    deleteOffer(request,response);
  }else if("update".equals(flag)) {
    updateOffer(request,response);
  }
}
​
//处理从数据库查询到的数据以返回前端
protected void queryOffer(HttpServletRequest request, HttpServletResponse response) {
  // TODO Auto-generated method stub
  List<Offer> offers = new ArrayList<Offer>();
  offers = offerservice.queryOfferService();
  try {
    String str=JSONArray.toJSONString(offers);//将数据库查询到的集合转换成JSON字符串
    System.out.println(str);
    response.setContentType("text/html;charset=utf-8");//防止response时中文数据乱码
    response.getWriter().print(str);//向前台传递字符串
  } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
  }
}

<table id="dg" title="用户列表" class="easyui-datagrid" style="width:80%;height:250px"
      url="<%=request.getContextPath() %>/OfferServlet"   
      toolbar="#toolbar"
      rownumbers="true" fitColumns="true" singleSelect="true">
    <thead>
      <tr>
        <th field="offerid" width="50">商品ID</th>
        <th field="offername" width="100">商品名称</th>
        <th field="offertype" width="200">商品类型</th>
        <th field="offerdesc" width="200">商品描述</th>
        <th field="price" width="200">商品价格</th>
      </tr>
    </thead>
  </table>

<table id="dg" title="用户列表" class="easyui-datagrid" style="width:1000px;height:250px" toolbar="#toolbar">
</table>

$(function(){
  $('#dg').datagrid({
    url:"${pageContext.request.contextPath}/OfferServlet",//servlet路径
    columns:[[
      {field:'offerid',title:'商品ID',width:100},
      {field:'offername',title:'商品名称',width:100},
      {field:'offertype',title:'商品类型',width:100},
      {field:'offerdesc',title:'商品描述',width:300},
      {field:'price',title:'商品价格',width:150}
    ]]   
  });
});