标签:import 不同 lazy 异常 变量 Matter input pac center
本来开开心心的周末时光,线上突然就疯狂报错,以为程序炸了,截停日志,发现是就是类似下述一段错误
java.lang.NumberFormatException: For input string: ".202006E.202006E44"
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:2089)
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.github.springtools.SimpleDateFormatTest.lambda$null$0(Xxxxxxx.java:2020)
at java.lang.Thread.run(Thread.java:748)
定位到错误处,发现是一个时间格式化(SimpleDateFormat)的异常,一个时间格式化怎么会导致这种错误,还使得接口不能正常调用
拉出来,使用模拟接口多线程的环境,单独进行测试.....
package com.github.springtools;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.stream.IntStream;
public class SimpleDateFormatTest {
public static final SimpleDateFormat FORMAT = new SimpleDateFormat("yyyy-MM-dd");
public static void main(String[] args) throws ParseException {
System.out.println(FORMAT.parse("2020-06-06"));
System.out.println("--------单个调用结束--------");
System.out.println("--------多线程调用开始--------");
IntStream.rangeClosed(0, 10)
.forEach(i -> new Thread(() -> {
try {
System.out.println(FORMAT.parse("2020-06-06"));
} catch (ParseException e) {
e.printStackTrace();
}
}).start());
}
}
输出
Sat Jun 06 00:00:00 CST 2020
--------单个调用结束--------
--------多线程调用开始--------
Sat Jun 06 00:00:00 CST 2020
Sat Jun 06 00:00:00 CST 2020
Exception in thread "Thread-7" Exception in thread "Thread-8" java.lang.NumberFormatException: For input string: ".202006E.202006E44"
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.lang.Double.parseDouble(Double.java:538)
罪魁祸手浮出水面,就是SimpleDateFormat
的锅
线程不安全,去找Java文档里的SimpleDateFormat
: https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html
Date formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.日期格式不同步。建议为每个线程创建单独的格式实例。如果多个线程同时访问一种格式,则必须在外部进行同步。
// ThreadLocal
public static final ThreadLocal<SimpleDateFormat> THREADLOCAL_FORMAT = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyy-MM-dd"));
IntStream.rangeClosed(0, 5)
.forEach(i -> new Thread(() -> {
try {
System.out.println("ThreadLocal:" + THREADLOCAL_FORMAT.get().parse("2020-06-06"));
} catch (ParseException e) {
e.printStackTrace();
}
}).start());
public static final DateTimeFormatter JAVA8_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
IntStream.rangeClosed(0, 5)
.forEach(i -> new Thread(() -> {
try {
System.out.println("JAVA8_FORMATTER:" + JAVA8_FORMATTER.parse("2020-06-06"));
} catch (ParseException e) {
e.printStackTrace();
}
}).start());
使用多线程的时候,一定要考虑到其调用到的实例变量,Java8中时间格式化DateTimeFormatter
是用final
修饰的,不可变类,所以是线程安全的,或者在线程中调用ThreadLocal
也是可以的
还在用SimpleDateFormat格式化时间?小心经理锤你
标签:import 不同 lazy 异常 变量 Matter input pac center
原文地址:https://www.cnblogs.com/cvandy/p/13057525.html