Question

我有两个不可变的 bean类，我使用Orika映射将值从一个复制到另一个。但是，当我尝试通过Orika映射复制unmodifiableList时，它会因为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，您可以使用该代码复制相同的问题：

EmployeeDto class：

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：

public final class Employee {
    //ditto AS EmployeeDto
}

OrikaTest课程：

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());
    }
}

我可以找到关于这个主题的链接here，但由于没有正确解释替代方案，因此不太清楚。

那么，您可以帮助解决如何通过Orika映射复制unmodifiableList的示例或任何解决方法吗？

Answer 1

如果案例是Orika必须能够改变映射对象的列表组件，那么以下可能是一个解决方法：

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，不再可能改变对象。

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;
    }
}

Orika Mapping for unmodifiable List

1 个答案: