JSON

新办法更通用：json新包统一用.fromObject( )方法转json，需要用json.lib包如：
JSONObject json=JSONObject.fromObject(data);

通过 $.parseJSON 转换为json数组

JSONSerializer.toJSON(heros)把集合转换为JSON字符串

1.需要先导入json的jar包

2. map转json：

Map map=new HashMap<>();
        map.put("s01", "zs");
        map.put("s02", "ls");
        map.put("s03", "ww");
        JSONObject json=new JSONObject(map);
        System.out.println(json);

结果：{"s02":"ls","s01":"zs","s03":"ww"}
3.b.javabean(普通对象 Person)转json、字符串转json
同样用JSONObject

private static void demo02() {
        Person per=new Person();
        per.setName("zs");
        per.setAge(23);
        Address address=new Address("西安","北京");
        per.setAddress(address);
        
        //Person(JavaBean)->json
        JSONObject json=new JSONObject(per);
        System.out.println(json);
        //{"address":{"schoolAddress":"北京",  "homeAddress":"西安"},
        // "name":"zs",
        // "age":23}
        
    }

    private static void demo03() {
        String str="{\"s02\":\"ls\",\"s01\":\"zs\",\"s03\":\"ww\"}";
        JSONObject json=new JSONObject(str);
        System.out.println(json);
    }   //{"s02":"ls","s01":"zs","s03":"ww"}

4.json转json文件
用 json.write( )方法。

        private static void demo03() throws JSONException, IOException {
             //准备json数据（map->json）
            Map map=new HashMap<>();
            Person p1=new Person(23,"zs",new Address("xa","bj1"));
            Person p2=new Person(24,"ls",new Address("xaq","bj2"));
            Person p3=new Person(25,"ww",new Address("xa2","bj3"));
            map.put("zs", p1);
            map.put("ls", p2);
            map.put("ww", p3);
            
            //map->json
            JSONObject json=new JSONObject(map);
            
            //生成json文件
        
         FileWriter fw=new FileWriter("C:\\Users\\zjh\\Desktop\\图片素材\\hello.txt");
        json.write(fw);
            fw.close();
        }

//输出结果：
{"ww":{"address":{"schoolAddress":"bj3","homeAddress":"xa2"},
"name":"ww",
"age":25},

"zs":{"address":{"schoolAddress":"bj1","homeAddress":"xa"},
"name":"zs",
"age":23},

"ls":{"address":{"schoolAddress":"bj2","homeAddress":"xaq"},
"name":"ls",
"age":24}}