json串的定义以及解析访问

json:是一种轻量级的数据交换格式。主要由数组和对象两种形式，通过不同的组合，形式复杂的json串。

1.      第一种json格式：

<script type="text/javascript">

    var p={"name":"ljf","age":"23"};

alert(p.name);

    alert(p.age);

  </script>

2.       第二种json格式：

 <script type="text/javascript">

  var people =[

                     {"firstName":"Brett","email": "[e-mail]" },

                     {"firstName":"Mary","email": "[e-mail]" }

                ];

  for(var k=0;k<people.length;k++){

  alert(people[k].firstName);

   }

 

 </script>

3.      第三种json格式：

 <script type="text/javascript">

    var people ={

           "programmers":

              [

                {"firstName":"Brett", "email": "[e-mail]" },

                {"firstName":"Jason", "email": "[e-mail]" }

              ]

};

var subName=people.programmers;

for(var k=0;k<subName.length;k++){

 

 alert(subName[k].firstName);

 

}

 

 </script>

4.      第四种json格式：

<scriptlanguage="JavaScript">

    varpeople ={

           "programmers": [

            { "firstName":"Brett", "email": "[e-mail]" },

           { "firstName": "Jason",  "email":"[e-mail]" },

           { "firstName": "Elliotte","lastName":"Harold", "email":"[e-mail]" }

          ],

         "authors": [

           { "firstName": "Isaac",  "genre": "sciencefiction" },

           { "firstName": "Tad", "genre":"fantasy" },

           { "firstName": "Frank",  "genre": "christianfiction" }

          ],

         "musicians": [

           { "firstName": "Eric",  "instrument": "guitar" },

           { "firstName": "Sergei", "instrument":"piano" }

          ]};

   window.alert(people.programmers[1].firstName);

   window.alert(people.musicians[1].instrument);

 </script>

5.       第五种json格式：

<script language="JavaScript">

     var people ={

            "username":"mary",

            "age":"20",

            "info":{"tel":"1234566","celltelphone":788666},

            "address":[

                    {"city":"beijing","code":"1000022"},

                     {"city":"shanghai","code":"2210444"}

              ]

       };

     window.alert(people.username);

     window.alert(people.info.tel);

     window.alert(people.address[0].city);

 </script>

后台的组合拼接：

    public static void main(String[] args) {

       JsonUtil su=new JsonUtil();

       String str="{'name':ljf}";

       String hou=su.string2json(str);

       System.out.println(hou);

       List<Ha> list=new ArrayList<Ha>();

       Ha ha=new Ha();

       ha.setAge("11");

       ha.setName("ljf");

       list.add(ha);

       Ha ha2=new Ha();

       ha2.setAge("34");

       ha2.setName("沙发");

       list.add(ha2);

       String jian=su.list2json(list);

       System.out.println(jian);

    }

结果显示:

{'name':ljf}

[{"age":"11","name":"ljf"},{"age":"34","name":"沙发"}]

3.json格式要求高，需要注意一下问题：

1.  Stringstr="{'name':'"+name+"','pwd':'"+pwd+"'}";//键值对均采用单引号

{'name':'d','pwd':'d'}

2.Stringstr="{\"name\":\" "+name+"\",\"pwd\":\" "+pwd+ " \"}";//键值对采用双引号

{"name":" 4","pwd":" d3 "}

2.  Stringstr="{'name':"+name+",'pwd':"+pwd+"}";//值没有采用引号，在前台获取不到数据；

总结：确保json串的键和值都得有引号；