---

前言

一、保留指定小数位

import org.apache.commons.lang3.StringUtils;
import java.math.BigDecimal;

public class OffSetPointUtil {

    /**
     * 保留指定小数位数
     *
     * @param value 原始double值
     * @param scale 小数位数
     * @return 保留指定小数位数后的字符串形式
     */
    public static String round(double value, int scale) {
        if (scale < 0) {
            throw new IllegalArgumentException("小数位数不能为负数");
        }
        BigDecimal bd = BigDecimal.valueOf(value);
        bd = bd.setScale(scale, BigDecimal.ROUND_HALF_UP);
        if (StringUtils.indexOf(bd.toString(), ".0") != -1) {
            return bd.toString().substring(0, StringUtils.indexOf(bd.toString(), ".0"));
        }
        return bd.toString();
    }
}

二、获取bean

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;


@Component
@Order(98)
public class SpringUtil implements ApplicationContextAware {

    private static Logger logger = LoggerFactory.getLogger(SpringUtil.class);
    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        if (SpringUtil.applicationContext == null) {
            SpringUtil.applicationContext = applicationContext;
        }
        logger.info("ApplicationContext配置成功,applicationContext对象：" + SpringUtil.applicationContext);
    }

    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }
}

三、假分页计算

包含一些自定义类，可根据项目具体封装结构修改

import com.gsafety.bg.gsdss.common.page.PageResult;
import org.springframework.data.domain.Pageable;

import java.util.List;
public class PageStaticUtils<T> {

    /**
     * 后端计算分页
     *
     * @param list list
     * @param page page
     * @return PageResult
     */
    public PageResult<T> pageData(List<T> list, Pageable page) {
        int total = list.size();
        int pages = (total / page.getPageSize()) + (total % page.getPageSize() > 0 ? 1 : 0);
        int start = page.getPageSize() * page.getPageNumber();
        int end = Math.min((start + page.getPageSize()), total);
        PageResult<T> pageResult = new PageResult<T>();
        pageResult.setNowPage(page.getPageNumber() + 1);
        pageResult.setPages(pages);
        pageResult.setPageSize(page.getPageSize());
        pageResult.setTotal(total);
        pageResult.setList(list.subList(start, end));
        return pageResult;
    }
}

四、星期计算

import java.time.LocalDate;

public class DayOfWeekUtil {

    public static String week(LocalDate day) {
        String[][] strArray = {{"MONDAY", "一"}, {"TUESDAY", "二"}, {"WEDNESDAY", "三"}, {"THURSDAY", "四"}, {"FRIDAY", "五"}, {"SATURDAY", "六"}, {"SUNDAY", "日"}};
        String k = String.valueOf(day.getDayOfWeek());
        //获取行数
        for (int i = 0; i < strArray.length; i++) {
            if (k.equals(strArray[i][0])) {
                k = strArray[i][1];
                break;
            }
        }
        return "星期" + k;
    }

}

五、经纬度计算距离

import lombok.experimental.UtilityClass;

@UtilityClass
public class DistanceUtil {

    /**
     * 地球平均半径
     */
    private static final double EARTH_RADIUS = 6378137;


    private static double rad(double d) {
        return d * Math.PI / 180.0;
    }

    /**
     * 根据两点间经纬度坐标（double值），计算两点间距离，单位为米
     *
     * @param centerLng 初始点经度
     * @param centerLat 初始点纬度
     * @param targetLng 目标点经度
     * @param targetLat 目标点纬度
     */
    public static double getDistance(double centerLng, double centerLat, double targetLng, double targetLat) {
        double radLat1 = rad(centerLat);
        double radLat2 = rad(targetLat);
        double a = radLat1 - radLat2;
        double b = rad(centerLng) - rad(targetLng);
        double s = 2 * Math.asin(
                Math.sqrt(
                        Math.pow(Math.sin(a / 2), 2)
                                + Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)
                )
        );
        s = s * EARTH_RADIUS;
        s = Math.round(s * 10000) / 10000;
        return s;
    }
}