Java 日期格式化 DateFormat

悠悠 2022-05-19 09:57 253阅读 0赞

**DateFormat**： 抽象类不能实例化，可以用`getTimeInstance`, `getDateInstance`, or `getDateTimeInstance 得到对象。`

具体介绍：[https://docs.oracle.com/javase/6/docs/api/java/text/DateFormat.html][https_docs.oracle.com_javase_6_docs_api_java_text_DateFormat.html]

通过**getDateInstance**() 得到格式化对象

*  **SHORT** is completely numeric, such as 12.13.52 or 3:30pm
 *  **MEDIUM** is longer, such as Jan 12, 1952
 *  **LONG** is longer, such as January 12, 1952 or 3:30:32pm
 *  **FULL** is pretty completely specified, such as Tuesday, April 12, 1952 AD or 3:30:42pm PST

DateFormat dfLONG = DateFormat.getDateInstance(DateFormat.LONG, Locale.CHINA);

**SimpleDateFormat**： 更简单得到格式化对象

参数含义：[https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html][https_docs.oracle.com_javase_6_docs_api_java_text_SimpleDateFormat.html]

DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd E a HH:mm:ss");

测试代码：

package com.DL;
    
    /**
     * @author 段乐
     * 日期格式化测试
     */
    
    import java.text.DateFormat;
    import java.text.ParseException;
    import java.text.SimpleDateFormat;
    import java.util.*;
    
    public class DateFormatTest {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		Date date = new Date();
    		System.out.println(date);
    		/**
    		 * 使用getDateInstance方法得到格式化对象
    		 * */
    		DateFormat dfFULL = DateFormat.getDateInstance(DateFormat.FULL);
    		DateFormat dfLONG = DateFormat.getDateInstance(DateFormat.LONG, Locale.CHINA);
    		DateFormat dfMEDIUM = DateFormat.getDateInstance(DateFormat.MEDIUM, Locale.CHINA);
    		DateFormat dfSHOT = DateFormat.getDateInstance(DateFormat.SHORT, Locale.CHINA);
    		System.out.println(dfFULL.format(date));
    		System.out.println(dfLONG.format(date));
    		System.out.println(dfMEDIUM.format(date));
    		System.out.println(dfSHOT.format(date));
    		/**
    		 * 压缩成Date类
    		 */
    		String myString = "2018年07月24日 星期二";
    		try {
    			Date myDate = dfFULL.parse(myString);
    			System.out.println(myDate);
    		} catch (ParseException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		/**
    		 * 使用SimpleDateFormat创建格式化对象
    		 */
    		DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd E a HH:mm:ss");
    		System.out.println(sdf.format(date));
    		
    	}
    
    }

运行结果：

![70][]

[https_docs.oracle.com_javase_6_docs_api_java_text_DateFormat.html]: https://docs.oracle.com/javase/6/docs/api/java/text/DateFormat.html
[https_docs.oracle.com_javase_6_docs_api_java_text_SimpleDateFormat.html]: https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html
[70]: /images/20220519/841d47458dd547a886394e6b755a851a.png