Json格式及其解析方式

1、 json介绍

官网

{
 "code": 100000,
 "text": "你也好 嘻嘻"
   }

2、json的数据格式更易于阅读 数据量比较小 json格式有2种

1)对象 { } 2)数组 [ ]

例如：

[{"name":"小花","age":18},{"name":"小黑","age":19}]

例如：

{"company":
           [{"department": [
               { "firstName":"Bill" , "lastName":"Gates" },
               { "firstName":"George" , "lastName":"Bush" },
               { "firstName":"Thomas" , "lastName":"Carter" }
           ]},
           {
             "department": [
                { "firstName":"fgf" , "lastName":"guig" },
                { "firstName":"jhuy" , "lastName":"jjkj" },
                { "firstName":"srgf" , "lastName":"gfy" }
                ]}
                ]
            }

3、json解析的实现

有个特点 ：解析时有几层中括号（[]）就会使用到相应的几层for循环 脱去大括号用到JSONObject脱去中括号用到JSONArray 遍历里面内容 如果还有大括号再逐一转化成JSONObject

例如 对上面的第二个json格式进行解析

//读取文件中信息
        BufferedReader reader = new BufferedReader(new FileReader(new File(
                "test5.json")));
        StringBuffer buffer = new StringBuffer();
        String json = null;
        while ((json = reader.readLine()) != null) {
            buffer.append(json);
        }
        //将文件中信息转换成JSONObject对象 
        JSONObject object = new JSONObject(buffer.toString()); 
        //此时获得的是company里的数组内容
        JSONArray array = object.getJSONArray("company");
        //对company数组对象遍历 
        for (int i = 0; i < array.length(); i++) {
            //获取每个department 对象节点
            JSONObject object2 = array.getJSONObject(i);
            //由department遍历里面内容
            JSONArray array2 = object2.getJSONArray("department");
            for (int j = 0; j < array2.length(); j++) {
                JSONObject object3 = array2.getJSONObject(j);
                System.out.println(object3.getString("firstName")
                + object3.getString("lastName"));
            }
        }

例如对第一个json格式进行解析

BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("test.json")), "gbk"));
    String line = null;
    StringBuffer sb = new StringBuffer();
    while ((line = br.readLine()) != null) {
        sb.append(line);
    }
    br.close();
    //获取json
    String json =  sb.toString();
    //将json转换为JSON数组
    JSONArray array=new JSONArray(json);
    //循环数组
    for (int i = 0; i < array.length(); i++) {
        //获取JSON对象
        JSONObject obj = array.getJSONObject(i);
        //获取对象中的数据
        String name = obj.getString("name");
        String age = obj.getInt("age");
        System.out.println(name + "," + age);
    }