Java Mapstruct 1.4.x-iterable到nonit。示例使用目标点运算符工作

我想采用这里的样品

不同的是，使用“myString”运算符而不是某些嵌套属性。给定示例，我希望得到“myString”作为结果，因此字符串将成为新的目标

但是，使用点运算符什么都不会发生。什么都不会发生意味着mapstruct只创建一个新的String实例，而没有iterable到noniterable的映射。这是一种期望的行为吗

如本文所述，示例（取自上述样本）：

不打印任何内容，因为生成的代码如下所示：

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2021-02-13T15:34:11+0100",
    comments = "version: 1.4.2.Final, compiler: javac, environment: Java 11.0.5 (JetBrains s.r.o)"
)
public class SourceTargetMapperImpl implements SourceTargetMapper {

    @Override
    public String toTarget(Source s) {
        if ( s == null ) {
            return null;
        }

        String string = new String();

        return string;
    }
}

其他类保持原样

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另一个例子： 嗨，菲利普，很抱歉迟到了。我想向你展示另一个对我不起作用的用例，或者正如我所期望的那样，使用“qualifiedBy”-阿曲布他。我遗漏了什么

班级地址：

public class Address {

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Address(String name) {
        this.name = name;
    }

    private String name;

    @Override
    public String toString() {
        return "Address{" +
                "name='" + name + '\'' +
                '}';
    }
}

使用地址列表对客户进行分类：

public class CustomerManyAddresses {

    public List<Address> getAddresses() {
        return addresses;
    }

    public void setAddresses(List<Address> addresses) {
        this.addresses = addresses;
    }

    private List<Address> addresses;
}

以及测试：

public class CustomerAddressMapperTest {

    private AddressMapper addressMapper = Mappers.getMapper(AddressMapper.class);

    @Test
    public void testCustomerMapper() {

        CustomerManyAddresses customerManyAddresses = new CustomerManyAddresses();
        Address address1 = new Address("first");
        Address address2 = new Address("second");
        Address address3 = new Address("third");
        customerManyAddresses.setAddresses(Arrays.asList(address1, address2, address3));

        Address singleAddress = addressMapper.toSingle(customerManyAddresses);
        System.out.println(singleAddress);
    }
}

…它只打印新生成的地址，这里没有iterable到non iter。再次使用。生成的类：

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2021-02-20T11:05:53+0100",
    comments = "version: 1.4.2.Final, compiler: javac, environment: Java 11.0.5 (JetBrains s.r.o)"
)
public class AddressMapperImpl extends AddressMapper {

    @Override
    Address toSingle(CustomerManyAddresses customerManyAddresses) {
        if ( customerManyAddresses == null ) {
            return null;
        }

        String name = null;

        Address address = new Address( name );

        return address;
    }
}

---

MapStruct不允许映射到

字符串

。当您使用

target=“.”

时，您的意思是要将第一个元素的属性映射到目标的属性

您可以做的是将目标字符串包装到bean中，然后像那样进行映射

---

不过，我的建议是，当您只想取回字符串时，编写您自己的自定义方法。

您能在这里提供一个问题示例吗？当然。我刚刚更改了上面提到的示例：将类型返回到字符串，将目标返回到.operator，源仍然是myIntegers。但我稍后会提供它……好的。它可以根据定义不允许？或根据“尚未实施”不允许？；））非常感谢。但是Filip，对于非字符串的对象，也会观察到相同的行为。如果目标是直接对象，则不会映射。将只会有一个新实例。因此，如果您将类型字符串替换为所需的对象类型，您将得到该类型的空对象…，我的意思是使用“.”运算符在默认情况下工作。但是，当使用namedBy时，它不适用。您可以确认或伪造此语句吗？请仔细考虑一下，在使用自定义映射方法时使用“.”运算符并没有真正意义。“”运算符用于告诉MapStruct如何进行映射，当您自己进行映射时，它不会带来太多价值不，我们彼此误解。我将在接下来的几个小时内提供另一个示例。

@Mapper(uses = IterableNonInterableUtil.class)
public abstract class AddressMapper {

    @Mapping(target = ".", source = "addresses", qualifiedBy = FirstElement.class)
    abstract Address toSingle(CustomerManyAddresses customerManyAddresses);
}

public class CustomerAddressMapperTest {

    private AddressMapper addressMapper = Mappers.getMapper(AddressMapper.class);

    @Test
    public void testCustomerMapper() {

        CustomerManyAddresses customerManyAddresses = new CustomerManyAddresses();
        Address address1 = new Address("first");
        Address address2 = new Address("second");
        Address address3 = new Address("third");
        customerManyAddresses.setAddresses(Arrays.asList(address1, address2, address3));

        Address singleAddress = addressMapper.toSingle(customerManyAddresses);
        System.out.println(singleAddress);
    }
}

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2021-02-20T11:05:53+0100",
    comments = "version: 1.4.2.Final, compiler: javac, environment: Java 11.0.5 (JetBrains s.r.o)"
)
public class AddressMapperImpl extends AddressMapper {

    @Override
    Address toSingle(CustomerManyAddresses customerManyAddresses) {
        if ( customerManyAddresses == null ) {
            return null;
        }

        String name = null;

        Address address = new Address( name );

        return address;
    }
}