java.time新API 处理日期选择

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近期遇到一个需求，做数据查询的时候要求，根据当前时间的今天，昨天，本周，上周，上月，今年做查询。

开始用java的Calendar类实现，的确很繁琐。

public void test(Integer select){        Date satrtTime = null;        Calendar calendar = Calendar.getInstance();        Date endTime = calendar.getTime();        calendar.set(Calendar.HOUR_OF_DAY,0 );        calendar.set(Calendar.MINUTE,0 );        calendar.set(Calendar.SECOND,0 );        calendar.set(Calendar.MILLISECOND, 0);        Date tmp = calendar.getTime();        switch (select){            case 1:{                satrtTime = tmp;            }            break;            case 2:{                calendar.setTime(tmp);                calendar.add(Calendar.DAY_OF_MONTH,-1);                satrtTime = calendar.getTime();            }            break;            case 3:{                calendar.setTime(tmp);                calendar.add(Calendar.DAY_OF_MONTH,-2);                satrtTime = calendar.getTime();            }            break;            case 4:{                calendar.setTime(tmp);                int week = calendar.get(Calendar.DAY_OF_WEEK);                calendar.add(Calendar.DAY_OF_MONTH,-week+2);                satrtTime = calendar.getTime();            }            break;            case 5:{                //本月                calendar.setTime(tmp);                calendar.set(Calendar.DAY_OF_MONTH,1);                satrtTime = calendar.getTime();            }            break;            case 6:{                //上月                calendar.setTime(tmp);                calendar.add(Calendar.MONTH,-1);                calendar.set(Calendar.DAY_OF_MONTH,1);                satrtTime = calendar.getTime();            }            break;            case 7:{                //本年                calendar.setTime(tmp);                calendar.set(Calendar.MONTH,1);                calendar.set(Calendar.DAY_OF_MONTH,1);                satrtTime = calendar.getTime();            }            break;        }        System.out.println("start: "+ satrtTime +",end: " + endTime);    }

查了下java8新特性，有很好用的替代API，下面是实现

public void time(Integer selec){        LocalDate endTime = LocalDate.now();        LocalDateTime dateTime = null;        switch (select){            case 1:{                dateTime = endTime.atStartOfDay();            }            break;            case 2:{                dateTime = endTime.minusDays(1).atStartOfDay();            }            break;            case 3:{                dateTime = endTime.minusDays(2).atStartOfDay();            }            break;            case 4:{                int week = endTime.getDayOfWeek().getValue();                dateTime = endTime.minusDays(week-1).atStartOfDay();            }            break;            case 5:{                //本月                dateTime = endTime.withDayOfMonth(1).atStartOfDay();            }            break;            case 6:{                //上月                dateTime = endTime.minusMonths(1).withDayOfMonth(1).atStartOfDay();            }            break;            case 7:{                //本年                dateTime = endTime.withMonth(1).withDayOfMonth(1).atStartOfDay();            }            break;        }        ZoneId zone = ZoneId.systemDefault();        Instant instant = dateTime.atZone(zone).toInstant();        java.util.Date startTime = Date.from(instant);        System.out.println(new Date());        System.out.println(startTime);    }

JDBC

最新JDBC映射将把数据库的日期类型和Java 8的新类型关联起来：

SQL -> Java--------------------------date -> LocalDatetime -> LocalTimetimestamp -> LocalDateTime

Mybatis3.4.0以上使用新API，直接加入如下依赖

<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-typehandlers-jsr310</artifactId>
<version>1.0.1</version>
</dependency>

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