JSON

JSON(JavaScript Object Notation,js对象简谱)

一个特定的字符串语法结构

JSON格式的字符串，在前后端都可以很方便的和对象之间进行转换

    <script>
      // json中,属性值和属性名都需要用双引号包好,数字可以不做处理
      // 属性值可以是数组,对象,对象数组
      // var personStr ='{"属性名":"属性值","属性名":"属性值"}'
      // 在json中主要使用属性传递数据,不讨论方法的传递

      //创建一个json格式的字符串
      var personStr =
        '{"name":"张三","age":10,"dog":{"dname":"小花"},"loveSingers" :["张晓明","王晓东","李小黑"],"friends":[{"fname":"赵四儿"},{"fname":"玉田"},{"fname":"王小蒙"}] }';
      var person = JSON.parse(personStr);
      console.log(personStr);
      console.log(person);
      //可以通过逐层打点的方式,访问每一个属性

      //也可以将对象转换为json串
      var personstr1 = JSON.stringify(person);
      console.log(personstr1);
    </script>

在后端，同样可使用jackson工具对json串进行转换操作

我们需要使用到Jackson来对json串进行转换

Central Repository: com/fasterxml/jackson/core (maven.org)

    @Test
    public void test() {
        ObjectMapper objectMapper = new ObjectMapper();
        String personStr = objectMapper.writeValueAsString(person);//将 person对象转成json串

        ObjectMapper objectMapper1 = new ObjectMapper();
        Person person = objectMapper1.readValue(PersonStr, Person.class);//将personStr字符串转成Person类的对象person

    }

Map，List，数组的JSON串

@Test
public void test1() throws JsonProcessingException {
    //map集合转为JSON串
    Map map = new HashMap();
    map.put("a", "valuea");
    map.put("b", "valueb");
    map.put("c", "valuec");

    ObjectMapper objectMapper = new ObjectMapper();
    System.out.println(objectMapper.writeValueAsString(map));//{"a":"valuea","b":"valueb","c":"valuec"}
}

@Test
public void test2() throws JsonProcessingException {
    //List集合转为JSON串
    List list = new ArrayList();
    list.add("a");
    list.add("b");
    list.add("c");
    ObjectMapper objectMapper = new ObjectMapper();
    System.out.println(objectMapper.writeValueAsString(list));//["a","b","c"]
}

@Test
public void test3() throws JsonProcessingException {
    String[] data = {"a", "b", "c"};
    ObjectMapper objectMapper = new ObjectMapper();
    System.out.println(objectMapper.writeValueAsString(data));//["a","b","c"]
}