json 和java对象互相转换（java）-蒲公英云

json 和java对象互相转换（java）

小灰灰 2022-09-10 04:18 256阅读 0赞

java 解析json
1.使用 alibaba 的 fastJson
添加依赖或者jar
在这里插入图片描述
2.fastJson 简单使用

JSON > Java对象
java对象 > json

public class MyJson { 
    public static String jsonmap = "{\"001\":{\"name\":\"xiaohong\",\"password\":\"654321\"},\"002\":[{\"$ref\":\"$.001\"},{\"name\":\"xixi\",\"password\":\"789\"}]}";
    public static String jsonuser = "{\"name\":\"xiaohong\",\"password\":\"654321\"}";
    public static String jsonlist = "[{\"name\":\"xiaohong\",\"password\":\"654321\"},{\"name\":\"xixi\",\"password\":\"789\"}]";
    public static void main(String[] args) { 
        User user = new User();
        user.setName("xiaohong");
        user.setPassword("654321");
        List<User> list = new ArrayList<User>();
        list.add(user);
        list.add(new User("xixi","789"));
        Map map = new HashMap();
        map.put("001",user);
        map.put("002",list);
        // 1. json字符串 转换为 java 对象
        // toJsonString - java对象转换为json字符串
        System.out.println(JSONObject.toJSONString(user));
        System.out.println(JSONObject.toJSONString(list));
        System.out.println(JSONObject.toJSONString(map));
        // toJavaObject - json字符串转换为java对象
        System.out.println(JSONObject.parseObject(jsonuser,User.class));
        List list1 = JSONObject.parseObject(jsonlist, List.class);
        for(int i=0;i<list1.size();i++) { 
            System.out.println(JSONObject.parseObject(JSONObject.toJSONString(list1.get(i)),User.class));
        }
        Map map1 = JSONObject.parseObject(jsonmap, Map.class);
        Iterator iterator = map1.entrySet().iterator();
        while (iterator.hasNext()) { 
            Map.Entry entry= (Map.Entry) iterator.next();
            System.out.println("key :"+entry.getKey()+" value: " + entry.getValue());
        }
        // Json -- 实体类转换为json字符串
        System.out.println(JSON.toJSONString(user));
        System.out.println(JSON.toJSONString(list));
        System.out.println(JSON.toJSONString(map));
        // json -- json 转 java对象
        System.out.println(JSON.parseObject(jsonuser,User.class));
        List list2 = JSON.parseObject(jsonlist, List.class);
        for(int i=0;i<list2.size();i++) { 
            System.out.println(JSON.parseObject(JSON.toJSONString(list1.get(i)),User.class));
        }
        Map map2 = JSON.parseObject(jsonmap, Map.class);
        Iterator iterator2 = map1.entrySet().iterator();
        while (iterator2.hasNext()) { 
            Map.Entry entry= (Map.Entry) iterator2.next();
            System.out.println("key :"+entry.getKey()+" value: " + entry.getValue());
        }
    }
}