简易商品页——JSON

12 JSON

12.1 json是什么

JSON(JavaScript Object Notation) javascript对象表示方法

json只是对象的一种表示方式。

但是现在只要是进行数据传递的地方就用JSON。

12.2 json格式

{ key:value , key:value }     这就是一个json对象。

[ { key:value , key:value } , { key:value , key:value } ]    这就是一个json数组

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12.3 表示对象的方式

学员类：

public class Stu{

    private int sid;

    private String sname;

}

java表示对象:

Stu s1 = new Stu();

s1.setSid(1);

s1.setSname(“zhangsan”);

xml文件：

   

         zhangsan

json表示:

{“sid”:1,”sname”:”zhangsan”}

12.4 在js中使用json

<script type="text/javascript"> var stuObj = {"sid":1,"sname":"peterSUN"}; alert(stuObj.sid); stuObj.sname = "孙旭"; alert(stuObj.sname); var stuArr = [{"sid":1,"sname":"peterSUN"},{"sid":2,"sname":"孙旭"}]; alert(stuArr.length); alert(stuArr[0].sid); script>

12.5 在java中使用Json

实现将java对象转换成json对象。

实现将java集合转换成json数组。

12.5.1 使用第三方组件JSON-LIB

12.5.2 将java对象转换成json对象

public static void main(String[] args) {           List goodsList = new ArrayList();           Types type = new Types(1, "酒水");           Goods goods1 = new Goods(1, "伊利", 1000, 100, null, type, null);           Goods goods2 = new Goods(2, "蒙牛", 2000, 200, null, type, null);           goodsList.add(goods1);           goodsList.add(goods2);                     //将Java对象转换成json对象           JSONObject jsonObject = JSONObject.fromObject(goods1);           System.out.println(jsonObject.toString());                     //将Java集合转换成json数组           JSONArray jsonArray = JSONArray.fromObject(goodsList);           System.out.println(jsonArray.toString());      }

12.6 访问Servlet获取json数据

@WebServlet("/jsonsearch.do") public class GoodsJsonSearchController extends HttpServlet {      protected void doGet(HttpServletRequest request, HttpServletResponse response)                throws ServletException, IOException {           List goodsList = new ArrayList();           Types type = new Types(1, "酒水");           Goods goods1 = new Goods(1, "伊利", 1000, 100, null, type, null);           Goods goods2 = new Goods(2, "蒙牛", 2000, 200, null, type, null);           goodsList.add(goods1);           goodsList.add(goods2);           response.setCharacterEncoding("utf-8");           PrintWriter pw = response.getWriter();           pw.write(JSONArray.fromObject(goodsList).toString());      }      protected void doPost(HttpServletRequest request, HttpServletResponse response)                throws ServletException, IOException {           request.setCharacterEncoding("utf-8");           doGet(request, response);      } }

<script type="text/javascript"> $(function(){      $("#searchBtn").click(function(){           $.ajax({                type:"post",                url:"${pageContext.request.contextPath }/jsonsearch.do",                dataType: "json",                success:function(msg){                     for(var i =0;i                          alert(msg[i].goodsId);                          alert(msg[i].goodsName);                          alert(msg[i].goodsType.typeName);                     }                }           });      }); }) script>