Java 使用 Jackson 库直接将 CSV 文件转换为 JSON 文件
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directly convert CSV file to JSON file using the Hymanson library
提问by Daniel Ruf
I am using following code:
我正在使用以下代码：
CsvSchema bootstrap = CsvSchema.emptySchema().withHeader();
ObjectMapper mapper = new CsvMapper();
File csvFile = new File("input.csv"); // or from String, URL etc
Object user = mapper.reader(?).withSchema(bootstrap).readValue(new File("data.csv"));
mapper.writeValue(new File("data.json"), user);
It throws an error in my IDE saying cannot find symbol method withSchema(CsvSchema)but why? I have used the code from some examples.
它在我的 IDE 中抛出一个错误，cannot find symbol method withSchema(CsvSchema)但为什么？我使用了一些示例中的代码。
I don't know what to write into mapper.reader()as I want to convert any CSV file.
How can I convert any CSV file to JSON and save it to the disk?
我不知道该写什么，mapper.reader()因为我想转换任何 CSV 文件。
如何将任何 CSV 文件转换为 JSON 并将其保存到磁盘？
What to do next? The examples
接下来做什么？例子
采纳答案by Micha? Ziober
I think, you should use MappingIteratorto solve your problem. See below example:
我想，你应该用它MappingIterator来解决你的问题。见下面的例子：
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import com.fasterxml.Hymanson.databind.MappingIterator;
import com.fasterxml.Hymanson.databind.ObjectMapper;
import com.fasterxml.Hymanson.dataformat.csv.CsvMapper;
import com.fasterxml.Hymanson.dataformat.csv.CsvSchema;
public class HymansonProgram {
public static void main(String[] args) throws Exception {
File input = new File("/x/data.csv");
File output = new File("/x/data.json");
List<Map<?, ?>> data = readObjectsFromCsv(input);
writeAsJson(data, output);
}
public static List<Map<?, ?>> readObjectsFromCsv(File file) throws IOException {
CsvSchema bootstrap = CsvSchema.emptySchema().withHeader();
CsvMapper csvMapper = new CsvMapper();
MappingIterator<Map<?, ?>> mappingIterator = csvMapper.reader(Map.class).with(bootstrap).readValues(file);
return mappingIterator.readAll();
}
public static void writeAsJson(List<Map<?, ?>> data, File file) throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(file, data);
}
}
See this page: Hymanson-dataformat-csvfor more information and examples.
有关更多信息和示例，请参阅此页面：Hymanson-dataformat-csv。
