使用Jackson库直接将CSV文件转换为JSON文件

I am using following code:

我使用以下代码：

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，说找不到符号方法withSchema（CsvSchema），但为什么？我使用了一些例子中的代码。

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?

我不知道写入mapper.reader（）的内容，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

1 个解决方案

#1

I think, you should use MappingIterator to solve your problem. See below example:

我想，您应该使用MappingIterator来解决您的问题。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.jackson.databind.MappingIterator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.csv.CsvMapper;
import com.fasterxml.jackson.dataformat.csv.CsvSchema;

public class JacksonProgram {

    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: jackson-dataformat-csv for more information and examples.

有关更多信息和示例，请参阅此页面：jackson-dataformat-csv。

#1