java - 如何在构造函数中访问 application.properties 值

Question

我正在尝试使用@ConfigurationProperties从application.properties文件加载键值对。

应用程序属性

soap.action.segalRead=Segal/SegalRead
soap.action.mantilUpdate=Mantil/MantilUpdate

SoapUri.java

@ConfigurationProperties(prefix = "soap.action")
public class SoapUri {

    @NotNull
    private String segalRead;
    @NotNull
    private String mantilUpdate;

    //getters and setters
}

SoapUriTests.java

@RunWith(SpringRunner.class)
@SpringBootTest
public class SoapUriTests {

    @Autowired 
    private SoapUri soapUri;

    @Test
    public void testSoapUri_returnsSoapAction() {
        assertThat(soapUri.getSegalRead()).isEqualTo("Segal/SegalRead");
        assertThat(soapUri.getMantilUpdate()).isEqualTo("Mantil/MantilUpdate");
    }
}

上述单元测试效果很好。

但是，我需要在实际代码中使用 SoapUri 。考虑以下代码:

public class MantilUpdateReadVO extends RequestClientVO {

    @Autowired
    private SoapUri soapUri;

    public MantilUpdateReadVO(final MantilUpdate mantilUpdate) {
        super(mantilUpdate, soapUri.getMantilUpdate(), MantilUpdateResponse.class);
    }
}
public class RequestClientVO {

    private Object readRequest;
    private String serviceName;
    private Class<?> unmarshalTargetclass;

    public MwsRequestClientVO(Object readRequest, String serviceName, Class<?> unmarshalTargetclass) {
        super();
        this.readRequest = readRequest;
        this.serviceName = serviceName;
        this.unmarshalTargetclass = unmarshalTargetclass;
    }
    //getters and setters
}

上面提示:“在显式调用构造函数时无法引用实例字段soapUri”

有谁知道在 super() 的 constructor 中注入(inject) segalRead 和 mantilUpdate 的解决方法

Answer 1

您正在使用字段注入(inject)，这不是一个好主意。请参阅 Oliver Gierke 的 Why Field Injection is Evil了解详情。

该字段要在实例构造完成后才能注入(inject)；因此，您不能在构造过程中使用注入(inject)字段。

像这样更改代码:

    @Autowired
    public MantilUpdateReadVO(final SoapUri soapUri, final MantilUpdate mantilUpdate) {
        super(mantilUpdate, soapUri.getMantilUpdate(), MantilUpdateResponse.class);
    }

您还需要确保 MantilUpdateReadVO 是一个 Spring Bean；可能需要添加@Component。

祝你好运!