https://www.cnblogs.com/uu5666/p/6639829.html AJAX 是一种用于创建快速动态网页的技术。 通过在后台与服务器进行少量数据交换，AJAX 可以使网页实现异步更新。这意味着可以在不重新加载整个网页的情况下，对网页的某部分进行更新,用户体验非常好。 下面介绍两种动态加载DropDownList值的方法。 第一种： View层 12345678910111213141516171819202122232425<select id="funcNum" name="funcNum"></select><script>$(document).ready(function() { showFuncId();}function showFuncId(){ $('#funcNum').empty(); var ciValue = $('#funcNum'); ciValue.append('<option value="">Pls Select</option>');  $.ajax({        url : u,  //your actual url        type : 'post',         dataType : 'json',         success : function (opts) {                if (opts && opts.length > 0) {                    var html = [];                     for (var i = 0; i < opts.length; i++) {                         html.push('<option value="'+opts[i].id+'">'+opts[i].desc+'</option>');                      }                     ciValue.append(html.join(''));                 }           }  }); }</script>　 Controller层 123456response.setContentType("application/json");        response.setCharacterEncoding("utf-8");        PrintWriter writer = response.getWriter();        net.sf.json.JSONArray array = JSONArray.fromObject(new ArrayList());//The list that contains actual data,use a new arrayList instead here       writer.append(array.toString());        return null;　　 第二种： View层 12345678910111213141516171819202122232425<select id="funcNum" name="funcNum"></select><script>$(function(){   $.ajax({      type: 'POST',      url:url;//your actual url      dataType: 'json',      cache: false,      async:false,      success:function(data) {          $('#funcNum').get(0).options.length = 0;          $('#funcNum').append('<option value="">Pls Select</option>');            $.each(data, function(i, obj) {                var option = $('<option />');                option.val(obj.id);                option.text(obj.desc);                $('#funcNum').append(option);              });        },                error: function() {            alert("Error while getting func num results");        }    });});</script> Controller层 123456response.setContentType("application/json"); response.setCharacterEncoding("utf-8"); PrintWriter writer = response.getWriter(); net.sf.json.JSONArray array = JSONArray.fromObject(new ArrayList());//The list that contains actual data,use a new arrayList instead herewriter.append(array.toString()); return null; 　Note:    As JSON format supports the following data types .　 1Numberdouble- precision floating-point format in JavaScript2Stringdouble-quoted Unicode with backslash escaping3Booleantrue or false4Arrayan ordered sequence of values5Valueit can be a string, a number, true or false, null etc6Objectan unordered collection of key:value pairs7Whitespacecan be used between any pair of tokens8nullempty 　 for date value, need add config to fromObject, core code: 123JsonConfig config = new JsonConfig();           config.registerJsonBeanProcessor(java.sql.Date.class, new JsDateJsonBeanProcessor());           JSONArray array = JSONArray.fromObject(object, config);