ObjectMapper json转对象

ゝ一世哀愁。 2022-03-22 07:44 515阅读 0赞

其中有几个坑：一个是要转换的属性都写成小写的，暂时没有遇到bug；还有一个是如果不是一般的类型，比如我要转换的类里面包括一个ObjectMapper类，一直报错，最后发现把它变成static即可，如下

package com.example.demo.util;
    
    import com.fasterxml.jackson.databind.DeserializationFeature;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.fasterxml.jackson.databind.SerializationFeature;
    import org.apache.logging.log4j.util.Strings;
    
    public class Mage {
    
        private static ObjectMapper gson = new ObjectMapper();
    
    
        public static ObjectMapper getGson() {
            return gson;
        }
    
        public static void setGson(ObjectMapper gson) {
            Mage.gson = gson;
        }
    
        /**
         * 消息发送者
         */
        private String name;
    
        /**
         * 直播房间号
         */
        private String homeid;
    
        /**
         * 发送的消息
         */
        private String msg;
    
        /**
         * 是否是第一次发送，是则为第一次连入直播间
         */
        private boolean count;
    
        public boolean isCount() {
            return count;
        }
    
        public void setCount(boolean count) {
            this.count = count;
        }
    
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getHomeid() {
            return homeid;
        }
    
        public void setHomeid(String homeid) {
            this.homeid = homeid;
        }
    
        public String getMsg() {
            return msg;
        }
    
        public void setMsg(String msg) {
            this.msg = msg;
        }
    
        /**
         * 将json字符串转成Mage
         *
         * @param message
         * @return
         * @throws Exception
         */
        public Mage strChangeToMage(String message) throws Exception {
            // 转换为格式化的json
            gson.enable(SerializationFeature.INDENT_OUTPUT);
    
            // 如果json中有新增的字段并且是实体类类中不存在的，不报错
            gson.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
            return Strings.isEmpty(message) ? null : gson.readValue(message, Mage.class);
        }
    
        @Override
        public String toString() {
            return "Mage{" +
                    "name='" + name + '\'' +
                    ", homeid='" + homeid + '\'' +
                    ", msg='" + msg + '\'' +
                    ", count=" + count +
                    '}';
        }
    }

测试类

@Test
        public void contextLoads() {
            String str = "{\"name\":\"123\",\"homeid\":\"1\",\"count\":\"true\"}";
    
            Mage stu = new Mage();
            try {
                ObjectMapper objectMapper = new ObjectMapper();
                // 转换为格式化的json
                objectMapper.enable(SerializationFeature.INDENT_OUTPUT);
    
                // 如果json中有新增的字段并且是实体类类中不存在的，不报错
                objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    
                stu = objectMapper.readValue(str, Mage.class);
                System.out.println(stu.toString());
            } catch (JsonParseException e) {
                e.printStackTrace();
            } catch (JsonMappingException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
    
        }