Java - jak zapisać obiekt java do pliku CSV za pomocą biblioteki Jackson CSV

<dependency>

    <groupId>com.fasterxml.jackson.dataformat</groupId>

    <artifactId>jackson-dataformat-csv</artifactId>

    <version>2.9.9</version>

</dependency>

import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.databind.ObjectWriter;

import com.fasterxml.jackson.dataformat.csv.CsvMapper;

import com.fasterxml.jackson.dataformat.csv.CsvSchema;

​

import java.io.File;

import java.io.IOException;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

​

public class UserCsvWriter {

​

    public static void main(String[] args) throws IOException {

​

        // set correct directory as output

        File csvOutputFile = new File("C:\\csv_tests\\user_output.csv");

​

        UserDto userDto1 = new UserDto(1L, "Ann", 30);

        UserDto userDto2 = new UserDto(2L, "Seth", 28);

        UserDto userDto3 = new UserDto(3L, "Emm", 24);

​

        List<UserDto> list = new ArrayList<>(Arrays.asList(userDto1, userDto2, userDto3));

​

        CsvMapper mapper = new CsvMapper();

        mapper.configure(JsonGenerator.Feature.IGNORE_UNKNOWN, true);

​

        CsvSchema schema = CsvSchema.builder().setUseHeader(true)

                .addColumn("id")

                .addColumn("name")

                .addColumn("age")

                .build();

​

        ObjectWriter writer = mapper.writerFor(UserDto.class).with(schema);

​

        writer.writeValues(csvOutputFile).writeAll(list);

​

        System.out.println("Users saved to csv file under path: ");

        System.out.println(csvOutputFile);

    }

}

Users saved to csv file under path:

C:\csv_tests\user_output.csv

import com.fasterxml.jackson.annotation.JsonPropertyOrder;

​

@JsonPropertyOrder({"id", "name", "age"})

public class UserDto {

​

    private Long id;

    private String name;

    private Integer age;

​

    public UserDto() {

​

    }

​

    public UserDto(Long id, String name, Integer age) {

        this.id = id;

        this.name = name;

        this.age = age;

    }

​

    public Long getId() {

        return id;

    }

​

    public void setId(Long id) {

        this.id = id;

    }

​

    public String getName() {

        return name;

    }

​

    public void setName(String name) {

        this.name = name;

    }

​

    public Integer getAge() {

        return age;

    }

​

    public void setAge(Integer age) {

        this.age = age;

    }

​

    @Override

    public String toString() {

        return "UserDto{" +

                "id=" + id +

                ", name='" + name + '\'' +

                ", age=" + age +

                '}';

    }

}