NoSuchMethodException:java.time.LocalDateTime.<init>()使用Super CSV读取CSV

Question

我编写了一个实体,其中只包含一个LocalDateTime使用Super CSV的 CSV文件,ICsvDozerBeanWriter并且在使用a读取它时遇到错误ICsvDozerBeanReader.我能够成功读取和写入一个Date对象,但LocalDateTime无法正常工作.

我添加了super-csv-java8依赖项,写入部分似乎工作正常.

我在这个Github仓库中创建了一个小型演示应用程序来复制问题.运行main()方法,错误将输出到控制台.

这是我得到的例外:

2016-12-09 22:24:02.427 ERROR 50405 --- [           main] org.dozer.MappingProcessor               : Field mapping error -->
  MapId: null
  Type: null
  Source parent class: org.supercsv.io.dozer.CsvDozerBeanData
  Source field name: columns
  Source field type: class java.time.LocalDateTime
  Source field value: 2016-12-09T22:24:02.226
  Dest parent class: com.example.Entity
  Dest field name: dateTime
  Dest field type: java.time.LocalDateTime

org.dozer.MappingException: java.lang.NoSuchMethodException: java.time.LocalDateTime.<init>()
    at org.dozer.util.MappingUtils.throwMappingException(MappingUtils.java:82) ~[dozer-5.4.0.jar:na]
    at org.dozer.factory.ConstructionStrategies$ByConstructor.newInstance(ConstructionStrategies.java:261) ~[dozer-5.4.0.jar:na]
    at org.dozer.factory.ConstructionStrategies$ByConstructor.create(ConstructionStrategies.java:245) ~[dozer-5.4.0.jar:na]
    at org.dozer.factory.DestBeanCreator.create(DestBeanCreator.java:65) ~[dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.mapCustomObject(MappingProcessor.java:489) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.mapOrRecurseObject(MappingProcessor.java:446) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.mapFromFieldMap(MappingProcessor.java:342) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.mapField(MappingProcessor.java:288) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.map(MappingProcessor.java:248) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.map(MappingProcessor.java:197) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.map(MappingProcessor.java:187) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.map(MappingProcessor.java:124) [dozer-5.4.0.jar:na]
    at org.dozer.MappingProcessor.map(MappingProcessor.java:119) [dozer-5.4.0.jar:na]
    at org.dozer.DozerBeanMapper.map(DozerBeanMapper.java:120) [dozer-5.4.0.jar:na]
    at org.supercsv.io.dozer.CsvDozerBeanReader.readIntoBean(CsvDozerBeanReader.java:220) [super-csv-dozer-2.4.0.jar:na]
    at org.supercsv.io.dozer.CsvDozerBeanReader.read(CsvDozerBeanReader.java:160) [super-csv-dozer-2.4.0.jar:na]
    at com.example.DemoApplication.readEntities(DemoApplication.java:51) [classes/:na]
    at com.example.DemoApplication.main(DemoApplication.java:39) [classes/:na]
Caused by: java.lang.NoSuchMethodException: java.time.LocalDateTime.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082) ~[na:1.8.0_66]
    at java.lang.Class.getDeclaredConstructor(Class.java:2178) ~[na:1.8.0_66]
    at org.dozer.factory.ConstructionStrategies$ByConstructor.newInstance(ConstructionStrategies.java:257) ~[dozer-5.4.0.jar:na]
    ... 16 common frames omitted

org.dozer.MappingException: java.lang.NoSuchMethodException: java.time.LocalDateTime.<init>()
    at org.dozer.util.MappingUtils.throwMappingException(MappingUtils.java:82)
    at org.dozer.factory.ConstructionStrategies$ByConstructor.newInstance(ConstructionStrategies.java:261)
    at org.dozer.factory.ConstructionStrategies$ByConstructor.create(ConstructionStrategies.java:245)
    at org.dozer.factory.DestBeanCreator.create(DestBeanCreator.java:65)
    at org.dozer.MappingProcessor.mapCustomObject(MappingProcessor.java:489)
    at org.dozer.MappingProcessor.mapOrRecurseObject(MappingProcessor.java:446)
    at org.dozer.MappingProcessor.mapFromFieldMap(MappingProcessor.java:342)
    at org.dozer.MappingProcessor.mapField(MappingProcessor.java:288)
    at org.dozer.MappingProcessor.map(MappingProcessor.java:248)
    at org.dozer.MappingProcessor.map(MappingProcessor.java:197)
    at org.dozer.MappingProcessor.map(MappingProcessor.java:187)
    at org.dozer.MappingProcessor.map(MappingProcessor.java:124)
    at org.dozer.MappingProcessor.map(MappingProcessor.java:119)
    at org.dozer.DozerBeanMapper.map(DozerBeanMapper.java:120)
    at org.supercsv.io.dozer.CsvDozerBeanReader.readIntoBean(CsvDozerBeanReader.java:220)
    at org.supercsv.io.dozer.CsvDozerBeanReader.read(CsvDozerBeanReader.java:160)
    at com.example.DemoApplication.readEntities(DemoApplication.java:51)
    at com.example.DemoApplication.main(DemoApplication.java:39)
Caused by: java.lang.NoSuchMethodException: java.time.LocalDateTime.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.getDeclaredConstructor(Class.java:2178)
    at org.dozer.factory.ConstructionStrategies$ByConstructor.newInstance(ConstructionStrategies.java:257)

理想情况下,我想以yyyy-MM-dd格式将日期写入CSV文件,但一步一步!

Answer 1

虽然Super CSV 确实支持java.time.LocalDateTime通过它ParseLocalDateTime和FmtLocalDateTime单元处理器(都在super-csv-java8模块中提供)进行读写,但是Dozer试图实例化目标LocalDateTime对象而不是使用单元处理器的结果(这是Dozer 的一个已知问题 - 它不是支持Java 8时间).

这2个解决方法是......

使用CsvBeanReader

SWAP CsvDozerBeanReader出与CsvBeanReader.您将失去深度/索引映射支持,但从好的方面来说,它会快得多.

在DozerBeanMapper中配置Java 8支持

正如Dozer问题所讨论的那样,有一个dozer-jdk8支持库可以解决这个问题.

添加依赖项:

<dependency>
  <groupId>io.craftsman</groupId>
  <artifactId>dozer-jdk8-support</artifactId>
  <version>1.0.2</version>
</dependency>

配置一个DozerBeanMapper:

DozerBeanMapper beanMapper = new DozerBeanMapper();
beanMapper.setMappingFiles(Collections.singletonList("dozerJdk8Converters.xml"));

并提供给您CsvDozerBeanReader:

new CsvDozerBeanReader(reader, CsvPreference.STANDARD_PREFERENCE, beanMapper)

这是一个样板,但如果你真的需要Dozer支持,这将让你开始运行.

ps我已经创建了一个PR以更新文档 - 只列出了一个Java 8单元处理器,并且有堆!