Java传统的时间格式化的线程安全问题

package com.expgiga.Java8;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.*;

/**
* 测试传统时间格式化的线程安全问题
*/
public class TestSimpleDateFormat {
public static void main(String[] args) throws ExecutionException, InterruptedException {

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");

Callable<Date> task = new Callable<Date>() {
@Override
public Date call() throws Exception {
return sdf.parse("20170806");
}
};

ExecutorService pool = Executors.newFixedThreadPool(10);

List<Future<Date>> results = new ArrayList<>();

for (int i = 0; i < 10; i++) {
results.add(pool.submit(task));
}

for (Future<Date> future : results) {
System.out.println(future.get());
}
}
}

package com.expgiga.Java8;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
*
*/
public class DateFormatThreadLocal {

private static final ThreadLocal<DateFormat> df = new ThreadLocal<DateFormat>() {
protected DateFormat initialValue() {
return new SimpleDateFormat("yyyyMMdd");
}
};

public static Date convert(String source) throws ParseException {
return df.get().parse(source);
}
}

package com.expgiga.Java8;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.*;

/**
* 测试传统时间格式化的线程安全问题
*/
public class TestSimpleDateFormat {
public static void main(String[] args) throws ExecutionException, InterruptedException {

//        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");

Callable<Date> task = new Callable<Date>() {
@Override
public Date call() throws Exception {
//                return sdf.parse("20170806");
return DateFormatThreadLocal.convert("20170805");
}
};

ExecutorService pool = Executors.newFixedThreadPool(10);

List<Future<Date>> results = new ArrayList<>();

for (int i = 0; i < 10; i++) {
results.add(pool.submit(task));
}

for (Future<Date> future : results) {
System.out.println(future.get());
}

pool.shutdown();
}
}

package com.expgiga.Java8;

import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.*;

/**
* 测试传统时间格式化的线程安全问题
*/
public class TestSimpleDateFormat {
public static void main(String[] args) throws ExecutionException, InterruptedException {

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyyMMdd");

Callable<LocalDate> task = new Callable<LocalDate>() {
@Override
public LocalDate call() throws Exception {
return LocalDate.parse("20170806", dtf);
}
};

ExecutorService pool = Executors.newFixedThreadPool(10);

List<Future<LocalDate>> results = new ArrayList<>();

for (int i = 0; i < 10; i++) {
results.add(pool.submit(task));
}

for (Future<LocalDate> future : results) {
System.out.println(future.get());
}

pool.shutdown();
}
}