Question

Spring @Autowire字段为null，即使它在其他类中也可以正常工作。

public class SendRunner implements Runnable {

private String senderAddress;
@Autowired
private SubscriberService subscriberService;

    public SendRunner(String senderAddress) {
    this.senderAddress = senderAddress;
}

@Override
public void run() {
    sendRequest();
}

  private void sendRequest() {
    try {
        HashMap<String, String> dataMap = new HashMap<>();
        dataMap.put("subscriberId", senderAddress);
         HttpEntity<?> entity = new HttpEntity<Object>(dataMap, httpHeaders);
         Subscriber subscriber = subscriberService.getSubscriberByMsisdn(senderAddress);
        } catch (Exception e) {
          logger.error("Error occurred while trying to send api request", e);
    }
}

该类也作为调度程序servlet中的bean管理：

    <bean id="SendRunner" class="sms.dating.messenger.connector.SendRunner">
    </bean>

在这里，我得到subscriberService的空指针异常。这可能是什么原因？预先感谢。

Answer 1

能否请您用@Component或@Service注释SendRunner类，并将SendRunner包包含在componentscanpackage中

Answer 2

您的bean不在Spring Managed上下文中，可能是以下原因。

软件包sms.dating.messenger.connector不在组件扫描中。
您将通过使用new创建一个对象来退出Spring上下文（请参见下文），这样，您将不会获得自动装配的字段。
```
SendRunner  sendRunner = new SendRunner () ,
sendRunner.sendRequest();
```

只需检查我的实施方式即可。希望这会有所帮助。

@RestController
public class RestRequest {

@Autowired
SendRunner sendRunner;

@RequestMapping("/api")
public void Uri() {
    sendRunner.start();
   }
}

SendRunner类

@Service
public class SendRunner extends Thread{ 

@Autowired
private SubscriberService subscriberService;

@Override
public void run() {
    SendRequest();

}

private void SendRequest() {
    System.out.println("Object is " + subscriberService);
    String senderAddress = "address";
    subscriberService.getSubscriberByMsisdn(senderAddress);
}
}

下面是我点击REST API时打印的日志。

对象是com.example.demo.SubscriberService@40f33492

Answer 3

请尝试以下代码段

@Configuration
                public class Someclass{

                     @Autowired
                     private SubscriberService subscriberService;

                     Thread subscriberThread = new Thread() {
                                @Override
                                public void run() {
                                  try {
                        HashMap<String, String> dataMap = new HashMap<>();
                        dataMap.put("subscriberId", senderAddress);
                         HttpEntity<?> entity = new HttpEntity<Object>(dataMap, httpHeaders);
                         Subscriber subscriber = subscriberService.getSubscriberByMsisdn(senderAddress);
                        } catch (Exception e) {
                          logger.error("Error occurred while trying to send api request", e);
                    }

                                }
                            };

                }

春季的@Autowire字段为null，尽管在其他课程中也可以正常使用

3 个答案: