我使用 Super CSV's 将仅包含 LocalDateTime
的实体写入 CSV 文件ICsvDozerBeanWriter
,我在使用 ICsvDozerBeanReader
读回它时遇到错误。我能够成功读取和写入 Date
对象,但 LocalDateTime
不工作。
我添加了 super-csv-java8依赖和写作部分似乎工作正常。
我创建了一个小型演示应用程序 in this Github repo复制问题。运行 main() 方法,错误将输出到控制台。
这是我遇到的异常:
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,但一次一步!
最佳答案
虽然 Super CSV 确实支持通过它的 ParseLocalDateTime
读取和写入 java.time.LocalDateTime
和 FmtLocalDateTime
单元处理器(都在 super-csv-java8
模块中可用),Dozer 试图实例化目标 LocalDateTime
对象,而不是使用单元处理器的结果(它是一个known issue 使用 Dozer - 它不支持 Java 8 时间)。
2 种解决方法是...
使用 CsvBeanReader
将 CsvDozerBeanReader
换成 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
正如在 Dozer 问题上所讨论的那样,有一个 dozer-jdk8-support解决此问题的库。
添加依赖:
<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"));
并将其提供给您的CsvDozerBeanReader
:
new CsvDozerBeanReader(reader, CsvPreference.STANDARD_PREFERENCE, beanMapper)
这是一些样板文件,但如果您真的需要 Dozer 支持,这将使您启动并运行。
附注我创建了一个 PR拥有 documentation已更新 - 仅列出了一个 Java 8 单元处理器,并且还有堆!
关于java - NoSuchMethodException : java. time.LocalDateTime.<init>() 使用 Super CSV 读取 CSV,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41069953/