Java项目实践技术总结

项目java技术随笔总结

1.Double运算要使用BigDecimal

BigDecimal xDecimal = BigDecimal.valueOf(xEnd);

BigDecimal yDecimal = BigDecimal.valueOf(yEnd);

2.绝对值方法 .abs();

3.BigDecimal判断大于0

diffMax.compareTo(BigDecimal.ZERO) > 0

StringBuild 插入字符

StringBuilder lonSb = new StringBuilder(String.valueOf(lon));

StringBuilder latSb = new StringBuilder(String.valueOf(lat));

lonSb.insert(3, “.”);

latSb.insert(2, “.”);

LocalDateTime转成Unix时间戳

long unixStart = startTime.toInstant(ZoneOffset.ofHours(8)).toEpochMilli() / 1000;

LocalDateTim增减时间

LocalDateTime timeLocal = localDateTime.plusMinutes(5);

String转LocalDateTime

String time = “2020-12-09 11:13:04”

DateTimeFormatter df = DateTimeFormatter.ofPattern(“yyyy-MM-dd HH:mm:ss”);

LocalDateTime collisionTime = LocalDateTime.parse(time , df);

从配置文件引入参数变量

@Value("${collision.templateIdShort}")

String TemplateIdShort;

对LocalDateTime时间增加一分钟

LocalDateTime startTimeAddOne = startTime.plusMinutes(1);

Json将对象转成Json字符串

String collision = JSONObject.toJSONString(collisionRefValue);

Redis模板配置java四种类型API

ListOperations listOperations = redisTemplate.opsForList();

ZSetOperations zSet = redisTemplate.opsForZSet();

SetOperations setOperations = redisTemplate.opsForSet();

HashOperations hashOperations = redisTemplate.opsForHash();

Reid获取Hash

String endTime = (String) hashOperations.get(Constants.COLLISION_TIME_IMEI_KEY, collision.getImei());

zSe获取

Set engineInfoSet = zSet.rangeByScore(Constants.COLLISION_FIVE_MINUTES_DATA + “:” + collision.getImei(), unixStartAddOne, unixEnd);

Reidis 反序列话报错

Jackson反序列化错误：com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field的解决方法

出现这种问题的情况是由于JSON里面包含了实体没有的字段导致反序列化失败。

实体类加上@JsonIgnoreProperties(ignoreUnknown = true)

String字符串转换成LocalDateTime

LocalDateTime redisTime = LocalDateTime.parse(endTime,formatter);

把对象存储Redis中要注意存储成Json形式，这样反序列化可以选择任何想要的内容

String jsonObject = JSON.toJSONString(vehicleEngineInfo);

zSet.add(RedisKeyConstants.VEHICLE_REALTIME_REPORTING_DATA+":"+vehicleVin,jsonObject,item.getCollectionTime());

String routeInfoNewJson = JSON.toJSONString(routeInfoNew);

hashOperations.delete(RedisKeyConstants.VEHICLE_INIT_ROUTEINFO_KEY, vin);

mysql 判断时间

<![CDATA[ AND DATE_FORMAT(info.create_time,'%Y-%m-%d %H:%i:%s') >= DATE_FORMAT(#{revis.startTime},'%Y-%m-%d %H:%i:%s')]]>