JAVA中日期处理

一、日期和long类型数据的相互转换

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        //日期转换为long
        Date currentDateInDate = new Date();
        long currentDateInLong = currentDateInDate.getTime();
        System.out.println(currentDateInDate);
        System.out.println(currentDateInLong); 
    } 
}

二、long类型转换为日期

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        //日期转换为long
        long currentDateInLong = System.currentTimeMillis();
        Date currentDateInDate = new Date(currentDateInLong);
        System.out.println(currentDateInDate);
        System.out.println(currentDateInLong); 
    } 
}

三、日期格式化（将日期format成字符串）

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        //日期转换为long
        long currentDateInLong = System.currentTimeMillis();
        Date currentDateInDate = new Date(currentDateInLong);
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSS");
        String currentDateInString = sdf.format(currentDateInDate);
        System.out.print(currentDateInString);
    } 
}

四、日期的解析(将字符串转化为日期)

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        String currentDateInString = "2016-08-07 19:24:03.0528";
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSS");
        Date currentDateInDate = sdf.parse(currentDateInString);
        System.out.print(currentDateInDate);
    } 
}

五、利用Calendar类获取日期的各个部分

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        Calendar calendar = Calendar.getInstance();
        System.out.println("年:" + calendar.get(Calendar.YEAR));
        System.out.println("月:" + (calendar.get(Calendar.MONTH) + 1));
        System.out.println("日:" + calendar.get(Calendar.DAY_OF_MONTH));
    } 
}