OpenCSV，如何用自定义处理写入csv？
OpenCSV，如何用自定义处理写入csv？
提问于 2020-07-10 20:13:44
我正在尝试将POJO对象列表写入csv。我使用opencsv，代码非常少：
StatefulBeanToCsv sbc = new StatefulBeanToCsvBuilder(writer)
.withSeparator(CSVWriter.DEFAULT_SEPARATOR)
.build();我在阅读时使用自定义转换器，我也可以为写做类似的事情吗？例如：
- 如果字段的类型为List，则将其写为"a，b“。但是我想这样做："a，b".
- A字段是LocalDataTime类型的，我想用"MM/dd/yyyy“格式写它，并在输出csv.
中完全丢弃时间。
我希望输出是这样的：
date of issue,items
"02/22/2020","a,b"而不是：
date of issue,items
"2020-02-22T00:00","[a,b]"非常感谢您，感谢您的帮助:)
回答 1
Stack Overflow用户
回答已采纳
发布于 2020-07-10 21:42:22
您可以使用注释@CsvDate设置自定义日期格式，并使用@CsvBindAndSplitByName将列表转换为字符串。请找下面的例子：
import static java.time.temporal.ChronoUnit.MONTHS;
import com.opencsv.CSVWriter;
import com.opencsv.bean.CsvBindAndSplitByName;
import com.opencsv.bean.CsvBindByName;
import com.opencsv.bean.CsvDate;
import com.opencsv.bean.StatefulBeanToCsv;
import com.opencsv.bean.StatefulBeanToCsvBuilder;
import java.io.FileWriter;
import java.io.Writer;
import java.time.LocalDateTime;
import java.util.List;
public class Main {
public static void main(String[] args) throws Exception {
Writer writer = new FileWriter("example.csv");
StatefulBeanToCsv<Item> sbc = new StatefulBeanToCsvBuilder<Item>(writer)
.withSeparator(CSVWriter.DEFAULT_SEPARATOR)
.build();
List<Item> items = List.of(
new Item(LocalDateTime.now().minus(4, MONTHS), List.of("1", "s")),
new Item(LocalDateTime.now().minus(1, MONTHS), List.of("1", "d")),
new Item(LocalDateTime.now().minus(3, MONTHS), List.of("1", "2", "3"))
);
sbc.write(items);
writer.close();
}
public static class Item {
@CsvBindByName(column = "date")
@CsvDate(value = "yyyy-MM-dd'T'hh:mm")
private LocalDateTime date;
@CsvBindAndSplitByName(column = "list", elementType = String.class, writeDelimiter = ",")
private List<String> array;
Item(LocalDateTime date, List<String> array) {
this.date = date;
this.array = array;
}
public LocalDateTime getDate() {
return date;
}
public void setDate(LocalDateTime date) {
this.date = date;
}
public List<String> getArray() {
return array;
}
public void setArray(List<String> array) {
this.array = array;
}
}
}example.csv输出
"DATE","LIST"
"2020-03-10T02:37","1,s"
"2020-06-10T02:37","1,d"
"2020-04-10T02:37","1,2,3"页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/62841670
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