使用 mapstruct 将多个字段映射到 List

Question

例如，我有以下实体：

class Bank
{
String name;
String employee1;
String employee2;
}

还有一个 Dto 对象：

class BankDto
{
String name;
List<String> employeeList;
}

是否有正确的方法将 Bank 映射到 BankDto，以便将 employee1 和 employee2 字段添加到 employeeList 集合？

Answer 1

您可以通过在映射接口中添加后映射方法来解决您的问题：

@Mapper
public abstract class Mapper {

    public abstract BankDto getBankDto(Bank bank);

    @AfterMapping
    public void setEmployees(Bank bank, @MappingTarget BankDto bankDto) {
        bankDto.setEmployeeList(new List<String>());
        bankDto.getEmployeeList().add(bank.employee1);
        bankDto.getEmployeeList().add(bank.employee2);
    }
}

Answer 2

如果你想让你的代码更动态，你也可以使用反射，你可以增加或减少员工字段的数量，映射器会自动为你做这件事:

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

class Bank {
    String name;
    // you can add or remove employees here and the mapper still work as expected :
    String employee1;
    String employee2;
    String employee3;
    String employee4;
    String employee5;
}

class BankDto {
    String name;
    List<String> employeeList = new ArrayList<>();
}

class Mapper {
    static BankDto map(Bank bank) throws IllegalArgumentException, IllegalAccessException {
        BankDto dto = new BankDto();
        dto.name = bank.name;
        
        List<Field> fields = Stream.of(bank.getClass().getDeclaredFields()).filter(f -> f.getName().startsWith("emp"))
                .collect(Collectors.toList());
        for (Field f : fields) {
            if (!f.isAccessible()) {
                f.setAccessible(true);
                dto.employeeList.add((String) (f.get(bank)));
                f.setAccessible(false);
            }
            // System.out.println(f.get(bank)); //print fields with reflection
        }
        return dto;
    }
}

public class Main {
    public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException {
        Bank b = new Bank();
        b.name = "BNP";
        b.employee1 = "Amine";
        b.employee2 = "SAMI";
        b.employee3 = "RAMI";
        b.employee4 = "KARIM";
        b.employee5 = "ZIAD";

        BankDto dto = Mapper.map(b);
        System.out.println("********BankDTO*********");
        System.out.println("Bank name :   " + dto.name);
        System.out.println("*****************");
        System.out.println(dto.employeeList);
    }
}

输出：

********BankDTO*********
Bank name :   BNP
*****************
[Amine, SAMI, RAMI, KARIM, ZIAD]

你应该确保封装写getters setters ..

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