Date常用格式转换

# 创建date对象
Date date = new Date();

# 获取当前时间
Date date = new Date(System.currentTimeMillis());

long modifyTime = 100000;
Date date = new Date(modifTime);

//指定输出格式
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
simpleDateFormat.format(new Date());
//指定输出格式和指定语言
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.CHINA);

public SimpleDateFormat() {
    this(Locale.getDefault());
    this.pattern = defaultPattern();
    this.formatData = new DateFormatSymbols(Locale.getDefault());
}
public SimpleDateFormat(String pattern) {
    this(pattern, Locale.getDefault());
}
public SimpleDateFormat(String template, DateFormatSymbols value) {
    this(Locale.getDefault());
    validatePattern(template);
    pattern = template;
    formatData = (DateFormatSymbols) value.clone();
}
public SimpleDateFormat(String template, Locale locale) {
    this(locale);
    validatePattern(template);
    pattern = template;
    formatData = new DateFormatSymbols(locale);
}

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = simpleDateFormat.parse("2021-11-11 11:11:11");

Date date = new Date();
Instant instant = date.toInstant();
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());

LocalDateTime localDateTime = LocalDateTime.now();
Instant instant = localDateTime.atZone(ZoneId.systemDefault()).toInstant();
Date date = Date.from(instant);