JSON

1.下载jar包：

https://www.github.com/alibaba/fastjson/releases

https://www.mvnrepository.com/artifact/com.alibaba/fastjson

2.选取一个版本，点击下载jar

 

3.在项目下新建lib文件夹，将下载好的jar包拷贝至该目下 ：lib/fastjson-1.2.47.jar

 

4.将jar添加到环境变量下：

右键jar包--> build Path --> add to build path

 

5.使用

重要的类：JSON

1.将json格式的字符串转化为java中的一个对象

parseObject()

2.将java中的一个对象转化为json格式的字符串

toJSONString()

 

 

String p1 = "{"name": "lisi", "age": 18}";
    //Person p = new Person();

    //    String pno = p1.substring(1, p1.length() - 1);
    //    System.out.println(pno);
        
    //    String[] split = pno.split(",");
        
    //    String[] name = split[0].split(":");
    //    p.setName(name[1].trim());
    //    String[] age = split[1].split(":");
    //    p.setAge(Integer.parseInt(age[1].trim()));
        
    //System.out.println(p);
 //将字符串转成对象
    String p1 = "{"name": "lisi", "age": 18}";
        Person p = JSON.parseObject(p1,Person.class);
        System.out.println(p);
        
        //将jison转换成字符串
        Person p2 = new Person("laowang", 30);
        String result = JSON.toJSONString(p2);
        System.out.println(result);
        
        //接受来自js的数据
        //给js发送数据
  
        //将js中的数组字符串，转化为java中的List
        String l1 = "[{"name":"laowang","age":18},{"name":"laoma","age":30}]";
        List<Person> list = JSON.parseArray(l1, Person.class);
        System.out.println(list.get(0));
        System.out.println(list.get(1));
        
        //将java的list转化为json格式的数组字符串
        List l2 = new ArrayList<>();
        l2.add(new Person("zhangsan", 5));
        l2.add(new Person("lisi", 6));
        String result2 = JSON.toJSONString(l2);
        System.out.println(result2);

moel  mo = json.getObject( key="名称",moel.class)
格式转换
JSONObject Delivery = JSONObject.parseObject(JSON.toJSONString(json.get("Delivery")));
Purchase  p = json.getObject( "purchase",Purchase.class) ;
List<PurchaseSon> list = JSON.parseArray(JSON.toJSONString(json.get("purchaseSon")), PurchaseSon.class);