src/org/nutz/lang/Times.java
public static String getFirstDayOfMonth() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.DATE, 1);
        return format(DF_DATE, cal.getTime());
    }
public static String getFirstDayOfMonth() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.DATE, 1);
        return format(DF_DATE, cal.getTime());
    }
获取本月第一天

@return 本月第一天