Shulou(Shulou.com)06/02 Report--

This article mainly explains "how to use java8 format Date", the content of the article is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "how to use java8 format Date" bar!

SimpleDateFormat thread is not safe

It is well known that SimpleDateFormat thread is not safe, and many friends have been cheated by it.

Public class ExampleClass {private static final Pattern dateCreateP = Pattern.compile:\\ s * (. +)); private static final SimpleDateFormat sdf = new SimpleDateFormat ("HH:mm:ss dd.MM.yyyy"); public static void main (String [] args) {ExecutorService executor = Executors.newFixedThreadPool While (true) {executor.submit (new Runnable () {@ Override public void run () {workConcurrently ();}}) }} public static void workConcurrently () {Matcher matcher = dateCreateP.matcher: 19:30:55 03.05.2015); Timestamp startAdvDate = null; try {if (matcher.find ()) {String dateCreate = matcher.group (1) StartAdvDate = new Timestamp (sdf.parse (dateCreate). GetTime ());} catch (Throwable th) {th.printStackTrace ();} System.out.print ("OK");}}

And result:

OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK java.lang.NumberFormatException: For input string: ".201519E.2015192 E2" at sun.misc.FloatingDecimal.readJavaFormatString (FloatingDecimal.java:2043) at sun.misc.FloatingDecimal.parseDouble (FloatingDecimal.java:110) at java.lang.Double.parseDouble (Double.java:538) at java.text.DigitList.getDouble (DigitList.java:169) at java. Text.DecimalFormat.parse (DecimalFormat.java:2056) at java.text.SimpleDateFormat.subParse (SimpleDateFormat.java:1869) at java.text.SimpleDateFormat.parse (SimpleDateFormat.java:1514) at java.text.DateFormat.parse (DateFormat.java:364) at com.nonscalper.webscraper.processor.av.ExampleClass.workConcurrently (ExampleClass.java:37) at com.nonscalper.webscraper.processor.av.ExampleClass$1.run (ExampleClass.java:25) at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:511) at java.util .concurrent.FutureTask.run (FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:617) at java.lang.Thread.run (Thread.java:745) solution

Each time new (instantiate) SimpleDateFormat.

Use ThreadLocal to ensure that each thread can get a separate SimpleDateFormat.

Public class DateUtil {private static final ThreadLocal local = ThreadLocal.withInitial (()-> new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss")); public static String format (Date date) {return local.get (). Format (date);} public static Date parse (String dateStr) throws ParseException {return local.get (). Parse (dateStr);}}

FastDateFormat in commons-lang3.

Org.apache.commons commons-lang3 ${commons-lang3-version} performance comparison

How is the performance? jmh give me a hand. The source code can be found in: https://github.com/lets-mica/mica-jmh

# JMH version: 1.2 percent VM version: JDK 1.8.0,221, Java HotSpot (TM) 64-Bit Server VM, 25.221-b11Benchmark Mode Cnt Score Error UnitsnewSimpleDateFormat thrpt 5 114072.841 ±989.135 ops/sthreadLocal thrpt 5 348207.331 ±46014.175 ops/sfastDateFormat thrpt 5 434391.553 ±7799.593 ops/s

Results: fastDateFormat had the highest score. Of course. You think that's it?

Using Instant + DateTimeFormatter

In mica 1.2.1 we use Instant to transfer Date to DateTimeFormatter formatting.

Public static final DateTimeFormatter DATETIME_FORMATTER = DateTimeFormatter.ofPattern ("yyyy-MM-dd HH:mm:ss") .withZone (ZoneId.systemDefault ()); public String format (Date date) {return DATETIME_FORMATTER.format (date.toInstant ());}

Note: DateTimeFormatter formatting Instant requires a specified time zone.

Jdk 8 pressure test result # JMH version: 1.2 pressure VM version: JDK 1.8.0mm 221, Java HotSpot (TM) 64-Bit Server VM, 25.221-b11Benchmark Mode Cnt Score Error UnitsfastDateFormat thrpt 5 417338.980 56543.104 ops/stoInstantFormat thrpt 5 371028.709 72059.917 ops/sjdk 11 pressure test result # JMH version: 1.2 inch VM version: JDK 11.0.4, OpenJDK 64-Bit Server VM 11.0.4+10-b304.69Benchmark Mode Cnt Score Error UnitsfastDateFormat thrpt 5 384637.138 7402.690 ops/stoInstantFormat thrpt 5 487482.436 12490.986 ops/s Thank you for your reading The above is the content of "how to use java8 to format Date". After the study of this article, I believe you have a deeper understanding of how to use java8 to format Date, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.