不可修改清单的Orika对应

Question

我有两个不可变的 bean类，正在使用Orika映射将它们从一个值复制到另一个。 但是，当我尝试通过Orika映射复制unmodifiableList ，由于抛出以下异常而失败：

java.lang.UnsupportedOperationException 
at ma.glasnost.orika.ExceptionUtility.newMappingException(ExceptionUtility.java:55)
at ma.glasnost.orika.impl.MapperFacadeImpl.map(MapperFacadeImpl.java:681)
at ma.glasnost.orika.impl.MapperFacadeImpl.map(MapperFacadeImpl.java:650)
at com.myproject.OrikaTest.testEmployeeMapping

我提供了以下代码，可用来复制相同的问题：

EmployeeDto类：

public final class EmployeeDto {
    private final int id;
    private final String name;
    private final List<String> previousGrades;

    public EmployeeDto(int id, String name, List<String> previousGrades) {
        this.id = id;//validations removed
        this.name = name;//validations removed
        //Commented unmodifiableList as it does not work
        //this.previousGrades = Collections.unmodifiableList(previousGrades);
        this.previousGrades = previousGrades;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public List<String> getPreviousGrades() {
        //tried like this, even this does not work
        return Collections.unmodifiableList(previousGrades);
    }
}

员工类别：

public final class Employee {
    //ditto AS EmployeeDto
}

OrikaTest类：

public class OrikaTest {

    private static final MapperFactory mapperFactory = 
           new DefaultMapperFactory.Builder().build();

    private static final MapperFacade mapperFacade = 
             mapperFactory.getMapperFacade();

    @Test
    public void testEmployeeMapping() {
        List<String> employeeGrades = Arrays.asList("A", "B");
        Employee employee = new Employee(1234, "John", employeeGrades);

        EmployeeDto employeeDto = mapperFacade.map(employee, EmployeeDto.class);

        //tests using assertEquals
        Assert.assertEquals(employeeGrades, employeeDto.getPreviousGrades());
    }
}

我在这里可以找到有关此主题的链接，但是由于没有正确解释替代方法，因此不清楚。

因此，您能否提供有关如何通过Orika映射复制unmodifiableList的示例或任何变通方法？

Answer 1

如果情况是Orika必须能够更改映射对象的列表组件，则可以解决以下问题：

向对象添加freeze方法。 创建对象时，它们处于可变状态。 调用freeze后，就不再可能对对象进行突变。

可以这样实现：

public final class EmployeeDto {
    private final int id;
    private final String name;
    private List<String> previousGrades;

    public EmployeeDto(int id, String name, List<String> previousGrades) {
        this.id = id;//validations removed
        this.name = name;//validations removed
        this.previousGrades = previousGrades;
    }

    public void freeze() {
        previousGrades = Collections.unmodifiableList(previousGrades)
    }

    public List<String> getPreviousGrades() {
        return previousGrades;
    }
}