@Data
public class A {

    private String name;
    private List<Integer> ids;
}

@Data
public class B {

    private String name;
    private List<String> ids;
}


public class BeanUtilDemo {

    public static void main(String[] args) {
        A first = new A();
        first.setName("demo");
        first.setIds(Arrays.asList(1, 2, 3));

        B second = new B();
        BeanUtils.copyProperties(first, second);
        for (String each : second.getIds()) {// 类型转换异常
            System.out.println(each);
        }
    }
}

import org.easymock.cglib.beans.BeanCopier;
import java.util.Arrays;

public class BeanUtilDemo {
    public static void main(String[] args) {
        A first = new A();
        first.setName("demo");
        first.setIds(Arrays.asList(1, 2, 3));

        B second = new B();
        final BeanCopier beanCopier = BeanCopier.create(A.class, B.class, false);
        beanCopier.copy(first,second,null);

        for (String each : second.getIds()) {// 类型转换异常
            System.out.println(each);
        }
    }
}

import org.mapstruct.Mapper;
import org.mapstruct.factory.Mappers;

@Mapper
public interface Converter {
    Converter INSTANCE = Mappers.getMapper(Converter.class);

    B aToB(A car);
}

import java.util.Arrays;

public class BeanUtilDemo {
    public static void main(String[] args) {
        A first = new A();
        first.setName("demo");
        first.setIds(Arrays.asList(1, 2, 3));

        B second = Converter.INSTANCE.aToB(first);
        for (String each : second.getIds()) {// 正常
            System.out.println(each);
        }
    }
}

import java.util.ArrayList;
import java.util.List;
import javax.annotation.Generated;
import org.springframework.stereotype.Component;


@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    comments = "version: 1.3.1.Final, compiler: javac, environment: Java 1.8.0_202 (Oracle Corporation)"
)
@Component
public class ConverterImpl implements Converter {


    @Override
    public B aToB(A car) {
        if ( car == null ) {
            return null;
        }


        B b = new B();

        b.setName( car.getName() );
        b.setIds( integerListToStringList( car.getIds() ) );

        return b;
    }


    protected List<String> integerListToStringList(List<Integer> list) {
        if ( list == null ) {
            return null;
        }


        List<String> list1 = new ArrayList<String>( list.size() );
        for ( Integer integer : list ) {
            list1.add( String.valueOf( integer ) );
        }

        return list1;
    }
}

@Override
public B aToB(A car) {
    if ( car == null ) {
        return null;
    }

    B b = new B();

    b.setName( car.getName() );
    if ( car.getNumber() != null ) { // 问题出在这里
        b.setNumber( Long.parseLong( car.getNumber() ) );
    }
    b.setIds( integerListToStringList( car.getIds() ) );

    return b;
}

public final class A2BConverter {

    public static B from(A first) {
        B b = new B();
        b.setName(first.getName());
        b.setIds(first.getIds());
        return b;
    }
}