java - Spring : Autowired bean is null

Question

我正在开发一个 Spring-MVC 应用程序，我在其中 Autowiring 一个字段，但它被设置为 NULL。我在网上检查了同样问题的解决方案，正如他们所描述的那样，我不应该在工作时创建一个新的类实例，而是从 spring 中获取它。我也试过了，但它总是提示找不到资源。

这是类(class):

@Service
@Transactional
public class GoogleAuthorization{

    @Autowired
    private DriveQuickstart driveQuickstart;  // This guy is null

    public void saveCredentials(final String authCode) throws IOException {

        GoogleTokenResponse response = flow.newTokenRequest(authCode).setRedirectUri(CALLBACK_URI).execute();
        Credential credential = flow.createAndStoreCredential(response, null);
        System.out.println(" Credential access token is "+credential.getAccessToken());
        System.out.println("Credential refresh token is "+credential.getRefreshToken());
// It fails at below point.
        this.driveQuickstart.storeCredentials(credential);
    }

Controller 代码:

@RequestMapping(value = "/getgooglelogin")
    public String getGoogleLogin(HttpServletRequest request, HttpServletResponse response, HttpSession session,Model model) {

       /* ApplicationContext applicationContext = new ClassPathXmlApplicationContext("../WEB-INF/spring/root-context.xml");
        GoogleAuthorization helper = (GoogleAuthorization) applicationContext.getBean("helper");*/
        GoogleAuthorization helper = new GoogleAuthorization();
}

如上所示，我尝试通过 root-context.xml 获取它，但无论我放置什么路径，它都找不到。

DriveQuickStartImpl:

@Service
@Transactional
public class DriveQuickstartImpl implements DriveQuickstart{
// All these below guys work just fine. 
@Autowired
    private PersonService personService;

    @Autowired
    private GoogleDriveService googleDriveService;

    @Autowired
    private GroupAttachmentsService groupAttachmentsService;

    @Autowired
    private GroupAccountService groupAccountService;
}

我做错了什么。你能帮忙的话，我会很高兴。多谢。

更新

root-context.xml 所属的图像:

Answer 1

只需 Autowiring GoogleAuthorization 助手(您可以这样做，因为您已经在 Spring 管理的 Controller 中):

@Service
@Transactional
public class DriveQuickstartImpl implements DriveQuickstart{

    // Other stuff...

    @Autowired 
    private GoogleAuthorization helper;


    @RequestMapping(value = "/getgooglelogin")
public String getGoogleLogin(HttpServletRequest request, HttpServletResponse response, HttpSession session,Model model) {

       // use "helper"
}

如果您 Autowiring 帮助程序，它将由 Spring 注入(inject)和管理。所以 Spring 将正确地构建和 Autowiring 它。