Spring Cloud-RestTemplate不会注入到拦截器中 [英] Spring cloud - Resttemplate doesn't get injected in interceptor

问题描述

我在Spring Boot应用程序中创建了一个resttemplate，如下所示:

I created a resttemplate in my spring boot application like this:

@Configuration
public class MyConfiguration {

@LoadBalanced
@Bean
  RestTemplate restTemplate() {
    return new RestTemplate();
  }
}

自动接线时，在所有类中都可以正常工作.但是，在我的拦截器中，这引发了nullpointer异常.

This works fine in all classes when autowired. However, in my interceptor, this throws up nullpointer exception.

这可能是什么原因?如何在拦截器中配置负载平衡(使用功能区)resttemplate?

What could be the reason and how can I configure a loadbalanced (using Ribbon) resttemplate in my interceptor?

更新:

我的拦截器:

 public class MyInterceptor implements HandlerInterceptorAdapter {

  @Autowired
  RestTemplate restTemplate;

  public boolean preHandle(HttpServletRequest request,
    HttpServletResponse response, Object handler)
    throws Exception {

    HttpHeaders headers = new HttpHeaders();
    ...
    HttpEntity<String> entity = new HttpEntity<String>(headers);

    //restTemplate is null here
    ResponseEntity<String> result = 
    restTemplate.exchange("<my micro service url using service name>", 
                          HttpMethod.POST, entity, String.class);
    ...

    return true;
}

拦截器像这样添加到Spring Boot应用程序中:

Interceptor is added to spring boot application like this:

@Configuration  
public class MyConfigAdapter extends WebMvcConfigurerAdapter  {

@Override
public void addInterceptors(InterceptorRegistry registry) {
   registry.addInterceptor(new MyInterceptor()).addPathPatterns("/*");
    }
}

推荐答案

您误解了@Autowired的工作方式.一旦您new MyInterceptor()在@Bean方法之外，它就不会自动连接.

You misunderstand how @Autowired works. As soon as you new MyInterceptor() outside of a @Bean method, it will not get autowired.

执行以下操作:

@Configuration  
public class MyConfigAdapter extends WebMvcConfigurerAdapter  {

    @Autowired
    MyInterceptor myInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor).addPathPatterns("/*");
    }
}

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