feature: 时间多久以前的显示

server/src/main/java/com/pica/cloud/online/exam/analysis/server/utils/DateUtils.java

+package com.pica.cloud.online.exam.analysis.server.utils;
+
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
+
+/**
+ * @author wuminghao
+ * @date 2018/9/1 10:54
+ */
+public class DateUtils {
+    private static final long ONE_MINITE = 60;
+    private static final long ONE_HOUR = 3600;
+    private static final long ONE_DAY = 86400;
+
+    public static Calendar calendar = Calendar.getInstance();
+
+    public static String fromNow(Date date) {
+        calendar.setTime(date);
+
+        long time = date.getTime() / 1000;
+        long now = (new Date()).getTime() / 1000;
+        long interval = now - time;
+
+        if (interval <= ONE_MINITE) {
+          return interval + "秒前";
+        } else if (interval <= ONE_HOUR) {
+            return interval / ONE_MINITE + "分钟前";
+        } else if (interval <= ONE_DAY) {
+            return interval / ONE_HOUR + "小时前";
+        }
+
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
+        return sdf.format(date);
+    }
+}