fasterxml 해석 json 편

1
github demo:https://github.com/FasterXML/jackson-databind
2
maven 의존:

		 <dependency.version.jackson>2.8.8dependency.version.jackson>

        
        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-coreartifactId>
            <version>${dependency.version.jackson}version>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-databindartifactId>
            <version>${dependency.version.jackson}version>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-annotationsartifactId>
            <version>${dependency.version.jackson}version>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatypegroupId>
            <artifactId>jackson-datatype-jsr310artifactId>
            <version>${dependency.version.jackson}version>
        dependency>

		
		<dependency>
            <groupId>commons-beanutilsgroupId>
            <artifactId>commons-beanutilsartifactId>
            <version>1.7.0version>
        dependency>
    

JacksonUtil.java

public class JacksonUtil {
    private static final Logger LOGGER = LoggerFactory.getLogger(JacksonUtil.class);

    private static final ObjectMapper objectMapper = new ObjectMapper();

    static {
        /*
         *   false：        （ ：true        json   ）

         *    ，              Java/C++    ( ：/* //    )

         *   ：   json            （   ），       

         */
        objectMapper.configure(JsonParser.Feature.ALLOW_COMMENTS, true);
        /*
         *   false：           
    ，               （      ，   js   ）

         *   ：   json            （   ），       

         */
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
        /*
         *   false：               

         *    ，                      ( ：       ，   '\'')

         *   ：           ，   JSON   

         */
        objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        /*
         *   ：  false_            

         *    ，                   ( ：ASCII<32，   tab    )

         *   ：  false（  ） ，        ; true ，        

         */
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
        /*
         *              ，  ：false，    
         */
        objectMapper.configure(JsonParser.Feature.ALLOW_BACKSLASH_ESCAPING_ANY_CHARACTER, true);
        /**
         *        
         */
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.configure(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY, true);
        /**
         *   null
         */
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        objectMapper.setLocale(Locale.CHINA);
        objectMapper.configure(DeserializationFeature.UNWRAP_ROOT_VALUE, false);
        
        objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS,false);

        //  locadatetime   yyyy-MM-dd HH:mm:ss  
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class,
                new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        objectMapper.registerModule(javaTimeModule);
    }

    /**
     *    JSON
     *
     * @param object
     *              
     * @return String
     */
    public static String toJSONString(Object object) {
        String json = "";
        if (null == object) {
            return json;
        }
        try {
            json = objectMapper.writeValueAsString(object);
        } catch (IOException e) {
            LOGGER.error("Java   JSON   ！", e);
            e.printStackTrace();
        }
        return json;
    }

    /**
     *    JSON
     *
     * @param object
     *              
     * @param pattern
     *                     ，   "yyyy-MM-dd HH:mm:ss"
     * @return String
     */
    public static String toJSONString(Object object, String pattern) {
        String json = "";
        if (null == object) {
            return json;
        }
        ObjectMapper mapper = objectMapper;
        try {
            DateFormat dateFormat = new SimpleDateFormat(pattern);
            mapper = mapper.setDateFormat(dateFormat);
            json = mapper.writeValueAsString(object);
        } catch (IOException e) {
            LOGGER.error("Java   JSON   ！", e);
            e.printStackTrace();
        }
        return json;
    }

    /**
     *  json      java  
     * 
     * @param json
     *            json   
     * @param typeReference
     *               java    
     * @param 
     * @return
     */
    public static <T> T jsonToBean(String json, TypeReference typeReference) {
        try {
            return objectMapper.readValue(json, typeReference);
        } catch (Exception e) {
            LOGGER.error("jsonToBeanByTypeReference", e);
            e.printStackTrace();
        }
        return null;
    }

    /**
     * map  JavaBean
     */
    public static <T> T map2bean(Map map, Class<T> clazz) {
        return objectMapper.convertValue(map, clazz);
    }
}

3 사용
1 매 핑 엔 터 티
jsonToBean:

        List<JsonEntity> jsonEntityList = JacksonUtil.jsonToBean(message, new TypeReference<List<JsonEntity>>(){});
        

메모: enity 는 List 로 정의 하지 마 세 요.
2 직접 읽 기
예시:

    public List<UserEventEntity> parse(String message) throws IOException{
        List<UserEventEntity> list = new ArrayList<>();
        ObjectMapper objectMapper = new ObjectMapper();
        JsonNode jsonNode = objectMapper.readTree(message);
        boolean active = jsonNode.get("Hadoop:service=NameNode,name=FSNamesystem").get("tag.HAState").textValue().equals("active");
        if(active){
            JsonNode innerNode = objectMapper.readTree(jsonNode.get("Hadoop:service=NameNode,name=FSNamesystemState").get("TopUserOpCounts").textValue());
            /**
             * topUserOpCounts   ：
             * topUserOpCounts (string) : v (string)   String   v  ： （ innerNode）
             *
             *     {
             * 	    "timestamp": "2019-06-25T16:57:11+0800",
             * 	    "windows": [{
             * 		    "windowLenMs": 60000,
             * 		    "ops": [{
             * 			    "opType": "listStatus",
             * 			    "topUsers": [{
             * 					"user": "voyager",
             * 					"count": 82
             *                },
             *                {
             * 					"user": "wave_bi",
             * 					"count": 1
             *                }
             * 			    ],
             * 			    "totalCount": 83
             * 		    }]
             * 	     }]
             *      }
             *
             *       ，  set entity     ：
             *     timestamp :    timestamp   xxx
             *     opType    :    opType
             *     opTotalSum:  totalCount    topUsers   ，  user        
             *     userName  :   user
             *     opSum     :   count
             *     windowLenMs:    user 
             *
             *       ，      entity，  user = all ，     opTotalSum
             */
            String timestamp = innerNode.get("timestamp").textValue();
            innerNode.get("windows").forEach(e-> {
                long windowLenMs = e.get("windowLenMs").longValue();
                e.get("ops").forEach(f->{
                    String opType = f.get("opType").textValue();
                    long totalCount = f.get("totalCount").longValue();
                    UserEventEntity a = new UserEventEntity();
                    a.setUserName("all"); //        
                    a.setOpTotalSum(totalCount);
                    a.setOpSum(totalCount);
                    a.setOpType(opType);
                    a.setWindowLenMs(windowLenMs);
                    a.setTimestamp(timestamp);
                    list.add(a);
                    f.get("topUsers").forEach(g->{
                        String user = g.get("user").textValue();
                        long count = g.get("count").longValue();
                        UserEventEntity u = new UserEventEntity();
                        u.setTimestamp(timestamp);
                        u.setWindowLenMs(windowLenMs);
                        u.setOpType(opType);
                        u.setUserName(user);
                        u.setOpSum(count);
                        u.setOpTotalSum(totalCount);
                        list.add(u);
                    });
                });
            });
        }
        return list;
    }