json 和java对象互相转换（java）

小灰灰 2022-09-10 04:18 156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][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBARmlybemZiA_size_20_color_FFFFFF_t_70_g_se_x_16]  
**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());
            }
            
        }
    }

[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBARmlybemZiA_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220829/8f67a41511504afa93571f59ac0c06bb.png