java的DateFormat、SimpleDateFormate类源码的详解
抽象类Format的定义
public abstract class Format implements Serializable, Cloneable {
private static final long serialVersionUID = -299282585814624189L;
protected Format() {
}
public final String format (Object obj) {
return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
}
public abstract StringBuffer format(Object obj,
StringBuffer toAppendTo,
FieldPosition pos);
public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
return createAttributedCharacterIterator(format(obj));
}
public abstract Object parseObject (String source, ParsePosition pos);
public Object parseObject(String source) throws ParseException {
ParsePosition pos = new ParsePosition(0);
Object result = parseObject(source, pos);
if (pos.index == 0) {
throw new ParseException("Format.parseObject(String) failed",
pos.errorIndex);
}
return result;
}
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
// will never happen
throw new InternalError(e);
}
}
//
// Convenience methods for creating AttributedCharacterIterators from
// different parameters.
//
AttributedCharacterIterator createAttributedCharacterIterator(String s) {
AttributedString as = new AttributedString(s);
return as.getIterator();
}
AttributedCharacterIterator createAttributedCharacterIterator(
AttributedCharacterIterator[] iterators) {
AttributedString as = new AttributedString(iterators);
return as.getIterator();
}
AttributedCharacterIterator createAttributedCharacterIterator(
String string, AttributedCharacterIterator.Attribute key,
Object value) {
AttributedString as = new AttributedString(string);
as.addAttribute(key, value);
return as.getIterator();
}
AttributedCharacterIterator createAttributedCharacterIterator(
AttributedCharacterIterator iterator,
AttributedCharacterIterator.Attribute key, Object value) {
AttributedString as = new AttributedString(iterator);
as.addAttribute(key, value);
return as.getIterator();
}
public static class Field extends AttributedCharacterIterator.Attribute {
// Proclaim serial compatibility with 1.4 FCS
private static final long serialVersionUID = 276966692217360283L;
/**
* Creates a Field with the specified name.
*
* @param name Name of the attribute
*/
protected Field(String name) {
super(name);
}
}
interface FieldDelegate {
public void formatted(Format.Field attr, Object value, int start,
int end, StringBuffer buffer);
public void formatted(int fieldID, Format.Field attr, Object value,
int start, int end, StringBuffer buffer);
}
}DateFormat的定义
public abstract class DateFormat extends Format {
protected Calendar calendar;
protected NumberFormat numberFormat;
public final StringBuffer format(Object obj, StringBuffer toAppendTo,
FieldPosition fieldPosition)
{
if (obj instanceof Date)
return format( (Date)obj, toAppendTo, fieldPosition );
else if (obj instanceof Number)
return format( new Date(((Number)obj).longValue()),
toAppendTo, fieldPosition );
else
throw new IllegalArgumentException("Cannot format given Object as a Date");
}
public abstract StringBuffer format(Date date, StringBuffer toAppendTo,
FieldPosition fieldPosition);
public final String format(Date date)
{
return format(date, new StringBuffer(),
DontCareFieldPosition.INSTANCE).toString();
}
public Date parse(String source) throws ParseException
{
ParsePosition pos = new ParsePosition(0);
Date result = parse(source, pos);
if (pos.index == 0)
throw new ParseException("Unparseable date: \"" + source + "\"" ,
pos.errorIndex);
return result;
}
public abstract Date parse(String source, ParsePosition pos);
public Object parseObject(String source, ParsePosition pos) {
return parse(source, pos);
}
public final static DateFormat getTimeInstance()
{
return get(DEFAULT, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
}
public final static DateFormat getTimeInstance(int style)
{
return get(style, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
}
public final static DateFormat getTimeInstance(int style,
Locale aLocale)
{
return get(style, 0, 1, aLocale);
}
public final static DateFormat getDateInstance()
{
return get(0, DEFAULT, 2, Locale.getDefault(Locale.Category.FORMAT));
}
public final static DateFormat getDateInstance(int style)
{
return get(0, style, 2, Locale.getDefault(Locale.Category.FORMAT));
}
public final static DateFormat getDateInstance(int style,
Locale aLocale)
{
return get(0, style, 2, aLocale);
}
public final static DateFormat getDateTimeInstance()
{
return get(DEFAULT, DEFAULT, 3, Locale.getDefault(Locale.Category.FORMAT));
}
public final static DateFormat getDateTimeInstance(int dateStyle,
int timeStyle)
{
return get(timeStyle, dateStyle, 3, Locale.getDefault(Locale.Category.FORMAT));
}
public final static DateFormat
getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
{
return get(timeStyle, dateStyle, 3, aLocale);
}
public final static DateFormat getInstance() {
return getDateTimeInstance(SHORT, SHORT);
}
public static Locale[] getAvailableLocales()
{
LocaleServiceProviderPool pool =
LocaleServiceProviderPool.getPool(DateFormatProvider.class);
return pool.getAvailableLocales();
}
public void setCalendar(Calendar newCalendar)
{
this.calendar = newCalendar;
}
public Calendar getCalendar()
{
return calendar;
}
public void setNumberFormat(NumberFormat newNumberFormat)
{
this.numberFormat = newNumberFormat;
}
public NumberFormat getNumberFormat()
{
return numberFormat;
}
}DateFormat抽象类满足了大部分的时间显示需求，其提供了三个获取实例对象的方法：
DateFormat dateft= DateFormat.getDateInstance();
System.out.println(dateft.format(new Date()));
DateFormat dateft2=DateFormat.getTimeInstance();
System.out.println(dateft2.format(new Date()));
DateFormat dateft3=DateFormat.getDateTimeInstance();
System.out.println(dateft3.format(new Date()));
运行结果：
2018-8-20
14:55:39
2018-8-20 14:55:39
DateFormat df1 = null ; // 声明一个DateFormat
DateFormat df2 = null ; // 声明一个DateFormat
df1 = DateFormat.getDateInstance(DateFormat.YEAR_FIELD,new Locale("zh","CN")) ; // 得到日期的DateFormat对象
df2 = DateFormat.getDateTimeInstance(DateFormat.YEAR_FIELD,DateFormat.ERA_FIELD,new Locale("zh","CN")) ; // 得到日期时间的DateFormat对象
System.out.println("DATE：" + df1.format(new Date())) ; // 按照日期格式化
System.out.println("DATETIME：" + df2.format(new Date())) ; // 按照日期时间格式化
DATE：2019年9月3日
DATETIME：2019年9月3日 下午03时15分46秒 CST
格式化样式主要通过 DateFormat 常量设置。将不同的常量传入方法中，以控制结果的长度。DateFormat 类的常量如下。
- SHORT：完全为数字，如 12.5.10 或 5:30pm。
- MEDIUM：较长，如 May 10，2016。
- LONG：更长，如 May 12，2016 或 11:15:32am。
- FULL：是完全指定，如 Tuesday、May 10、2012 AD 或 11:l5:42am CST。
//获取不同格式化风格和中国环境的日期
DateFormat df1=DateFormat.getDateInstance(DateFormat.SHORT,Locale.CHINA);
DateFormat df2=DateFormat.getDateInstance(DateFormat.FULL,Locale.CHINA);
DateFormat df3=DateFormat.getDateInstance(DateFormat.MEDIUM,Locale.CHINA);
DateFormat df4=DateFormat.getDateInstance(DateFormat.LONG,Locale.CHINA);
//获取不同格式化风格和中国环境的时间
DateFormat df5=DateFormat.getTimeInstance(DateFormat.SHORT,Locale.CHINA);
DateFormat df6=DateFormat.getTimeInstance(DateFormat.FULL,Locale.CHINA);
DateFormat df7=DateFormat.getTimeInstance(DateFormat.MEDIUM,Locale.CHINA);
DateFormat df8=DateFormat.getTimeInstance(DateFormat.LONG,Locale.CHINA);
//将不同格式化风格的日期格式化为日期字符串
String date1=df1.format(new Date());
String date2=df2.format(new Date());
String date3=df3.format(new Date());
String date4=df4.format(new Date());
//将不同格式化风格的时间格式化为时间字符串
String time1=df5.format(new Date());
String time2=df6.format(new Date());
String time3=df7.format(new Date());
String time4=df8.format(new Date());
//输出日期
System.out.println("SHORT："+date1+" "+time1);
System.out.println("FULL："+date2+" "+time2);
System.out.println("MEDIUM："+date3+" "+time3);
System.out.println("LONG："+date4+" "+time4);
SHORT：18-10-15 上午9:30
FULL：2018年10月15日 星期一 上午09时30分43秒 CST
MEDIUM：2018-10-15 9:30:43
LONG：2018年10月15日 上午09时30分43秒
练习一：把Date对象转换成String
Date date = new Date(1607616000000L);//Fri Dec 11 00:00:00 CST 2020
DateFormat df = new SimpleDateFormat(“yyyy年MM月dd日”);
String str = df.format(date);
//str中的内容为2020年12月11日
练习二：把String转换成Date对象
String str = ”2020年12月11日”;
DateFormat df = new SimpleDateFormat(“yyyy年MM月dd日”);
Date date = df.parse( str );
//Date对象中的内容为Fri Dec 11 00:00:00 CST 2020
SimpleDateFormat
public class SimpleDateFormat extends DateFormat {
transient private NumberFormat originalNumberFormat;
transient private String originalNumberPattern;
transient private char minusSign = '-';
transient private boolean hasFollowingMinusSign = false;
transient private boolean forceStandaloneForm = false;
transient private char[] compiledPattern;
private Locale locale;
public SimpleDateFormat() {
this("", Locale.getDefault(Locale.Category.FORMAT));
applyPatternImpl(LocaleProviderAdapter.getResourceBundleBased().getLocaleResources(locale)
.getDateTimePattern(SHORT, SHORT, calendar));
}
public SimpleDateFormat(String pattern)
{
this(pattern, Locale.getDefault(Locale.Category.FORMAT));
}
public SimpleDateFormat(String pattern, Locale locale)
{
if (pattern == null || locale == null) {
throw new NullPointerException();
}
initializeCalendar(locale);
this.pattern = pattern;
this.formatData = DateFormatSymbols.getInstanceRef(locale);
this.locale = locale;
initialize(locale);
}
public SimpleDateFormat(String pattern, DateFormatSymbols formatSymbols)
{
if (pattern == null || formatSymbols == null) {
throw new NullPointerException();
}
this.pattern = pattern;
this.formatData = (DateFormatSymbols) formatSymbols.clone();
this.locale = Locale.getDefault(Locale.Category.FORMAT);
initializeCalendar(this.locale);
initialize(this.locale);
useDateFormatSymbols = true;
}
/* Initialize compiledPattern and numberFormat fields */
private void initialize(Locale loc) {
// Verify and compile the given pattern.
compiledPattern = compile(pattern);
/* try the cache first */
numberFormat = cachedNumberFormatData.get(loc);
if (numberFormat == null) { /* cache miss */
numberFormat = NumberFormat.getIntegerInstance(loc);
numberFormat.setGroupingUsed(false);
/* update cache */
cachedNumberFormatData.putIfAbsent(loc, numberFormat);
}
numberFormat = (NumberFormat) numberFormat.clone();
initializeDefaultCentury();
}
private void initializeCalendar(Locale loc) {
if (calendar == null) {
assert loc != null;
// The format object must be constructed using the symbols for this zone.
// However, the calendar should use the current default TimeZone.
// If this is not contained in the locale zone strings, then the zone
// will be formatted using generic GMT+/-H:MM nomenclature.
calendar = Calendar.getInstance(TimeZone.getDefault(), loc);
}
}
private char[] compile(String pattern) {
int length = pattern.length();
boolean inQuote = false;
StringBuilder compiledCode = new StringBuilder(length * 2);
StringBuilder tmpBuffer = null;
int count = 0, tagcount = 0;
int lastTag = -1, prevTag = -1;
for (int i = 0; i < length; i++) {
char c = pattern.charAt(i);
if (c == '\'') {
// '' is treated as a single quote regardless of being
// in a quoted section.
if ((i + 1) < length) {
c = pattern.charAt(i + 1);
if (c == '\'') {
i++;
if (count != 0) {
encode(lastTag, count, compiledCode);
tagcount++;
prevTag = lastTag;
lastTag = -1;
count = 0;
}
if (inQuote) {
tmpBuffer.append(c);
} else {
compiledCode.append((char)(TAG_QUOTE_ASCII_CHAR << 8 | c));
}
continue;
}
}
if (!inQuote) {
if (count != 0) {
encode(lastTag, count, compiledCode);
tagcount++;
prevTag = lastTag;
lastTag = -1;
count = 0;
}
if (tmpBuffer == null) {
tmpBuffer = new StringBuilder(length);
} else {
tmpBuffer.setLength(0);
}
inQuote = true;
} else {
int len = tmpBuffer.length();
if (len == 1) {
char ch = tmpBuffer.charAt(0);
if (ch < 128) {
compiledCode.append((char)(TAG_QUOTE_ASCII_CHAR << 8 | ch));
} else {
compiledCode.append((char)(TAG_QUOTE_CHARS << 8 | 1));
compiledCode.append(ch);
}
} else {
encode(TAG_QUOTE_CHARS, len, compiledCode);
compiledCode.append(tmpBuffer);
}
inQuote = false;
}
continue;
}
if (inQuote) {
tmpBuffer.append(c);
continue;
}
if (!(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z')) {
if (count != 0) {
encode(lastTag, count, compiledCode);
tagcount++;
prevTag = lastTag;
lastTag = -1;
count = 0;
}
if (c < 128) {
// In most cases, c would be a delimiter, such as ':'.
compiledCode.append((char)(TAG_QUOTE_ASCII_CHAR << 8 | c));
} else {
// Take any contiguous non-ASCII alphabet characters and
// put them in a single TAG_QUOTE_CHARS.
int j;
for (j = i + 1; j < length; j++) {
char d = pattern.charAt(j);
if (d == '\'' || (d >= 'a' && d <= 'z' || d >= 'A' && d <= 'Z')) {
break;
}
}
compiledCode.append((char)(TAG_QUOTE_CHARS << 8 | (j - i)));
for (; i < j; i++) {
compiledCode.append(pattern.charAt(i));
}
i--;
}
continue;
}
int tag;
if ((tag = DateFormatSymbols.patternChars.indexOf(c)) == -1) {
throw new IllegalArgumentException("Illegal pattern character " +
"'" + c + "'");
}
if (lastTag == -1 || lastTag == tag) {
lastTag = tag;
count++;
continue;
}
encode(lastTag, count, compiledCode);
tagcount++;
prevTag = lastTag;
lastTag = tag;
count = 1;
}
if (inQuote) {
throw new IllegalArgumentException("Unterminated quote");
}
if (count != 0) {
encode(lastTag, count, compiledCode);
tagcount++;
prevTag = lastTag;
}
forceStandaloneForm = (tagcount == 1 && prevTag == PATTERN_MONTH);
// Copy the compiled pattern to a char array
int len = compiledCode.length();
char[] r = new char[len];
compiledCode.getChars(0, len, r, 0);
return r;
}
private static void encode(int tag, int length, StringBuilder buffer) {
if (tag == PATTERN_ISO_ZONE && length >= 4) {
throw new IllegalArgumentException("invalid ISO 8601 format: length=" + length);
}
if (length < 255) {
buffer.append((char)(tag << 8 | length));
} else {
buffer.append((char)((tag << 8) | 0xff));
buffer.append((char)(length >>> 16));
buffer.append((char)(length & 0xffff));
}
}
private void initializeDefaultCentury() {
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.add( Calendar.YEAR, -80 );
parseAmbiguousDatesAsAfter(calendar.getTime());
}
@Override
public StringBuffer format(Date date, StringBuffer toAppendTo,
FieldPosition pos)
{
pos.beginIndex = pos.endIndex = 0;
return format(date, toAppendTo, pos.getFieldDelegate());
}
// Called from Format after creating a FieldDelegate
private StringBuffer format(Date date, StringBuffer toAppendTo,
FieldDelegate delegate) {
// Convert input date to time field list
calendar.setTime(date);
boolean useDateFormatSymbols = useDateFormatSymbols();
for (int i = 0; i < compiledPattern.length; ) {
int tag = compiledPattern[i] >>> 8;
int count = compiledPattern[i++] & 0xff;
if (count == 255) {
count = compiledPattern[i++] << 16;
count |= compiledPattern[i++];
}
switch (tag) {
case TAG_QUOTE_ASCII_CHAR:
toAppendTo.append((char)count);
break;
case TAG_QUOTE_CHARS:
toAppendTo.append(compiledPattern, i, count);
i += count;
break;
default:
subFormat(tag, count, delegate, toAppendTo, useDateFormatSymbols);
break;
}
}
return toAppendTo;
}
@Override
public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
StringBuffer sb = new StringBuffer();
CharacterIteratorFieldDelegate delegate = new
CharacterIteratorFieldDelegate();
if (obj instanceof Date) {
format((Date)obj, sb, delegate);
}
else if (obj instanceof Number) {
format(new Date(((Number)obj).longValue()), sb, delegate);
}
else if (obj == null) {
throw new NullPointerException(
"formatToCharacterIterator must be passed non-null object");
}
else {
throw new IllegalArgumentException(
"Cannot format given Object as a Date");
}
return delegate.getIterator(sb.toString());
}
@Override
public Date parse(String text, ParsePosition pos)
{
checkNegativeNumberExpression();
int start = pos.index;
int oldStart = start;
int textLength = text.length();
boolean[] ambiguousYear = {false};
CalendarBuilder calb = new CalendarBuilder();
for (int i = 0; i < compiledPattern.length; ) {
int tag = compiledPattern[i] >>> 8;
int count = compiledPattern[i++] & 0xff;
if (count == 255) {
count = compiledPattern[i++] << 16;
count |= compiledPattern[i++];
}
switch (tag) {
case TAG_QUOTE_ASCII_CHAR:
if (start >= textLength || text.charAt(start) != (char)count) {
pos.index = oldStart;
pos.errorIndex = start;
return null;
}
start++;
break;
case TAG_QUOTE_CHARS:
while (count-- > 0) {
if (start >= textLength || text.charAt(start) != compiledPattern[i++]) {
pos.index = oldStart;
pos.errorIndex = start;
return null;
}
start++;
}
break;
default:
// Peek the next pattern to determine if we need to
// obey the number of pattern letters for
// parsing. It's required when parsing contiguous
// digit text (e.g., "20010704") with a pattern which
// has no delimiters between fields, like "yyyyMMdd".
boolean obeyCount = false;
// In Arabic, a minus sign for a negative number is put after
// the number. Even in another locale, a minus sign can be
// put after a number using DateFormat.setNumberFormat().
// If both the minus sign and the field-delimiter are '-',
// subParse() needs to determine whether a '-' after a number
// in the given text is a delimiter or is a minus sign for the
// preceding number. We give subParse() a clue based on the
// information in compiledPattern.
boolean useFollowingMinusSignAsDelimiter = false;
if (i < compiledPattern.length) {
int nextTag = compiledPattern[i] >>> 8;
if (!(nextTag == TAG_QUOTE_ASCII_CHAR ||
nextTag == TAG_QUOTE_CHARS)) {
obeyCount = true;
}
if (hasFollowingMinusSign &&
(nextTag == TAG_QUOTE_ASCII_CHAR ||
nextTag == TAG_QUOTE_CHARS)) {
int c;
if (nextTag == TAG_QUOTE_ASCII_CHAR) {
c = compiledPattern[i] & 0xff;
} else {
c = compiledPattern[i+1];
}
if (c == minusSign) {
useFollowingMinusSignAsDelimiter = true;
}
}
}
start = subParse(text, start, tag, count, obeyCount,
ambiguousYear, pos,
useFollowingMinusSignAsDelimiter, calb);
if (start < 0) {
pos.index = oldStart;
return null;
}
}
}
// At this point the fields of Calendar have been set. Calendar
// will fill in default values for missing fields when the time
// is computed.
pos.index = start;
Date parsedDate;
try {
parsedDate = calb.establish(calendar).getTime();
// If the year value is ambiguous,
// then the two-digit year == the default start year
if (ambiguousYear[0]) {
if (parsedDate.before(defaultCenturyStart)) {
parsedDate = calb.addYear(100).establish(calendar).getTime();
}
}
}
// An IllegalArgumentException will be thrown by Calendar.getTime()
// if any fields are out of range, e.g., MONTH == 17.
catch (IllegalArgumentException e) {
pos.errorIndex = start;
pos.index = oldStart;
return null;
}
return parsedDate;
}
private int matchString(String text, int start, int field, String[] data, CalendarBuilder calb)
{
int i = 0;
int count = data.length;
if (field == Calendar.DAY_OF_WEEK) {
i = 1;
}
// There may be multiple strings in the data[] array which begin with
// the same prefix (e.g., Cerven and Cervenec (June and July) in Czech).
// We keep track of the longest match, and return that. Note that this
// unfortunately requires us to test all array elements.
int bestMatchLength = 0, bestMatch = -1;
for (; i<count; ++i)
{
int length = data[i].length();
// Always compare if we have no match yet; otherwise only compare
// against potentially better matches (longer strings).
if (length > bestMatchLength &&
text.regionMatches(true, start, data[i], 0, length))
{
bestMatch = i;
bestMatchLength = length;
}
}
if (bestMatch >= 0)
{
calb.set(field, bestMatch);
return start + bestMatchLength;
}
return -start;
}
private int matchString(String text, int start, int field,
Map<String,Integer> data, CalendarBuilder calb) {
if (data != null) {
// TODO: make this default when it's in the spec.
if (data instanceof SortedMap) {
for (String name : data.keySet()) {
if (text.regionMatches(true, start, name, 0, name.length())) {
calb.set(field, data.get(name));
return start + name.length();
}
}
return -start;
}
String bestMatch = null;
for (String name : data.keySet()) {
int length = name.length();
if (bestMatch == null || length > bestMatch.length()) {
if (text.regionMatches(true, start, name, 0, length)) {
bestMatch = name;
}
}
}
if (bestMatch != null) {
calb.set(field, data.get(bestMatch));
return start + bestMatch.length();
}
}
return -start;
}如果使用 DateFormat 类格式化日期/时间并不能满足要求，那么就需要使用 DateFormat 类的子类——SimpleDateFormat。
SimpleDateFormat 是一个以与语言环境有关的方式来格式化和解析日期的具体类，它允许进行格式化（日期→文本）、解析（文本→日期）和规范化。SimpleDateFormat 使得可以选择任何用户定义的日期/时间格式的模式。
SimpleDateFormat 类主要有如下 3 种构造方法。
- SimpleDateFormat()：用默认的格式和默认的语言环境构造 SimpleDateFormat。
- SimpleDateFormat(String pattern)：用指定的格式和默认的语言环境构造 SimpleDateF ormat。
- SimpleDateFormat(String pattern,Locale locale)：用指定的格式和指定的语言环境构造 SimpleDateF ormat。
编写 Java 程序，使用 SimpleDateFormat 类格式化当前日期并打印，日期格式为“xxxx 年 xx 月 xx 日星期 xxx 点 xx 分 xx 秒”，具体的实现代码如下：
import java.text.SimpleDateFormat;
import java.util.Date;
public class Test13
{
public static void main(String[] args)
{
Date now=new Date(); //创建一个Date对象，获取当前时间
//指定格式化格式
SimpleDateFormat f=new SimpleDateFormat("今天是 "+"yyyy 年 MM 月 dd 日 E HH 点 mm 分 ss 秒");
System.out.pnntln(f.format(now)); //将当前时间袼式化为指定的格式
}
}
今天是 2018 年 10 月 15 日 星期一 09 点 26 分 23 秒
获取当前时间
import hunter.text.SimpleDateFormat;
import java.util.Date;
public class Main{
public static void main(String[] args){
SimpleDateFormat sdf = new SimpleDateFormat();// 格式化时间
sdf.applyPattern("yyyy-MM-dd HH:mm:ss a");// a为am/pm的标记
Date date = new Date();// 获取当前时间
System.out.println("现在时间：" + sdf.format(date)); // 输出已经格式化的现在时间（24小时制）
}
}
时间戳转换成时间
import hunter.text.SimpleDateFormat;
import java.util.Date;
public class Main{
public static void main(String[] args){
Long timeStamp = System.currentTimeMillis(); //获取当前时间戳
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
String sd = sdf.format(new Date(Long.parseLong(String.valueOf(timeStamp)))); // 时间戳转换成时间
System.out.println(sd);
}
}
package dates;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
public class TestSimpleDateFormat {
public static void main(String args[]) throws ParseException {
TestSimpleDateFormat test = new TestSimpleDateFormat();
test.testDateFormat();
}
public void testDateFormat() throws ParseException {
//创建日期
Date date = new Date();
//创建不同的日期格式
DateFormat df1 = DateFormat.getInstance();
DateFormat df2 = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss EE");
DateFormat df3 = DateFormat.getDateInstance(DateFormat.FULL, Locale.CHINA); //产生一个指定国家指定长度的日期格式，长度不同，显示的日期完整性也不同
DateFormat df4 = new SimpleDateFormat("yyyy年MM月dd日 hh时mm分ss秒 EE", Locale.CHINA);
DateFormat df5 = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss EEEEEE", Locale.US);
DateFormat df6 = new SimpleDateFormat("yyyy-MM-dd");
DateFormat df7 = new SimpleDateFormat("yyyy年MM月dd日");
//将日期按照不同格式进行输出
System.out.println("-------将日期按照不同格式进行输出------");
System.out.println("按照Java默认的日期格式，默认的区域 : " + df1.format(date));
System.out.println("按照指定格式 yyyy-MM-dd hh:mm:ss EE ，系统默认区域 :" + df2.format(date));
System.out.println("按照日期的FULL模式，区域设置为中文 : " + df3.format(date));
System.out.println("按照指定格式 yyyy年MM月dd日 hh时mm分ss秒 EE ，区域为中文 : " + df4.format(date));
System.out.println("按照指定格式 yyyy-MM-dd hh:mm:ss EE ，区域为美国 : " + df5.format(date));
System.out.println("按照指定格式 yyyy-MM-dd ，系统默认区域 : " + df6.format(date));
//将符合该格式的字符串转换为日期，若格式不相配，则会出错
Date date1 = df1.parse("07-11-30 下午2:32");
Date date2 = df2.parse("2007-11-30 02:51:07 星期五");
Date date3 = df3.parse("2007年11月30日 星期五");
Date date4 = df4.parse("2007年11月30日 02时51分18秒 星期五");
Date date5 = df5.parse("2007-11-30 02:51:18 Friday");
Date date6 = df6.parse("2007-11-30");
System.out.println("-------输出将字符串转换为日期的结果------");
System.out.println(date1);
System.out.println(date2);
System.out.println(date3);
System.out.println(date4);
System.out.println(date5);
System.out.println(date6);
}
}
标签：java,String,DateFormat,int,SimpleDateFormate,源码,Date,new,public From： https://blog.51cto.com/u_11837698/6081996