数组的 Jackson-CSV 模式

Question

I have CSV file which I need to parse. The schema for this file is following:

name, contacts - where contacts are many strings for each person where the number of this contact columns is not regular.

For example:

john, john@wick.com, 123 123 123, fb/john.wick
mike, 123 0303 11
dave,

I'm trying to create a CsvSchema with Jacskon CSV for my bean:

public class Person {
    private String name;
    private String[] contacts;
}

By creating custom schema:

CsvSchema schema = CsvSchema.builder()
    .addColumn("name")
    .addArrayColumn("contacts", ",")
    .build(); 

But I am getting this:

com.fasterxml.jackson.dataformat.csv.CsvMappingException: Too many entries: expected at most 2

How to with Jackson CSV solve problem like that?

Java code:

CsvMapper mapper = new CsvMapper();
CsvSchema schema = CsvSchema.builder()
    .addColumn("name")
    .addArrayColumn("contacts", ",")
    .build();
MappingIterator<Person> it = mapper.readerFor(Person.class).with(schema)
    .readValues(csvString);
List<Person> all = it.readAll();

Answer 1

You can use CsvParser.Feature.WRAP_AS_ARRAY feature and read whole row as List<String> . In constructor you can convert List to Person object. See below example:

import com.fasterxml.jackson.databind.MappingIterator;
import com.fasterxml.jackson.dataformat.csv.CsvMapper;
import com.fasterxml.jackson.dataformat.csv.CsvParser;

import java.io.File;
import java.util.List;
import java.util.stream.Collectors;

public class CsvApp {

    public static void main(String[] args) throws Exception {
        File csvFile = new File("./resource/test.csv").getAbsoluteFile();

        CsvMapper csvMapper = new CsvMapper();
        csvMapper.enable(CsvParser.Feature.WRAP_AS_ARRAY);

        MappingIterator<List<String>> rows = csvMapper.readerFor(List.class).readValues(csvFile);
        List<Person> persons = rows.readAll().stream()
                .filter(row -> !row.isEmpty())
                .map(Person::new)
                .collect(Collectors.toList());

        persons.forEach(System.out::println);
    }
}

class Person {

    private String name;
    private List<String> contacts;

    public Person(List<String> row) {
        this.name = row.remove(0);
        this.contacts = row;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<String> getContacts() {
        return contacts;
    }

    public void setContacts(List<String> contacts) {
        this.contacts = contacts;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", contacts=" + contacts +
                '}';
    }
}

For your input above code prints:

Person{name='john', contacts=[john@wick.com, 123 123 123, fb/john.wick]}
Person{name='mike', contacts=[123 0303 11]}
Person{name='dave', contacts=[]}

Answer 2

I think the problem is with the column separator being the same as the array column separator.

You can use ; instead of , in your CSV.

Should be: john,john@wick.com;123 123 123;fb/john.wick

This way you can continue to use the features of Jackson instead of having to manually instantiate from a List of Strings.