如何使用依赖注入在 Spring 中注入资源 Class 实例

Question

我是 Spring 的新手。有一个例子，我写了一个 Class 来实现 AutoCloseable 接口。现在我想用它作为依赖注入。

我担心的是，如果我使用 @Autowired 并稍后在函数中使用它，会 Spring 在结束范围或任何异常后自动关闭资源对象吗？

@RestController
@RequestMapping("/rest/profile")
public class ProfileController {

   private Daws haws;


   @Autowired
   public ProfileController(Daws haws) {
      this.haws = haws;
   }

   @RequestMapping(value = "/images/{userId}/{fileName:.+}", method = RequestMethod.GET)
   public void image(@PathVariable Integer userId, @PathVariable String publicUrl, @PathVariable String fileName, HttpServletRequest request, HttpServletResponse response) throws Exception {
      try{
         S3Object image = haws.getProfileImage(userId, fileName, request);

         response.setContentType(image.getObjectMetadata().getContentType());
         response.setHeader("ETag",image.getObjectMetadata().getETag());
         response.setHeader("Cache-Control",image.getObjectMetadata().getCacheControl());
         response.setHeader("Last-Modified",image.getObjectMetadata().getLastModified().toString());
         IOUtils.copy(image.getObjectContent(), response.getOutputStream());
      }catch (Exception e) {
         if(e instanceof AmazonS3Exception){
            //....
            //....
            response.setStatus(statusCode);
         }
     }
 }

//Daws class
public class Daws implements AutoCloseable{
    public S3Object getProfileImage(int userId, String fileName, HttpServletRequest request) throws IOException, ParseException, AmazonS3Exception{

        S3Object image = ....;

        return image;
    }

    @Override
    public void close() throws Exception {
       // TODO Auto-generated method stub
    }
}

我现在就是这样做的。请告诉我它是否正常或资源泄漏。如果是，那我该怎么办？

Answer 1

对于 Spring 托管 bean，您可以实现 DisposableBean interface or use @PreDestroy 注释。 Spring 应用上下文被销毁时会调用destroy方法

如果您需要在每次方法调用时创建和关闭对象，您应该使用 try-with-resources

Answer 2

如果您不使用 try-with-resources 或明确调用 close()

，AutoCloseable 将永远不会被 Spring 关闭

void close() throws Exception Closes this resource, relinquishing any underlying resources. This method is invoked automatically on objects managed by the try-with-resources statement.

来自 javadoc

如何使用依赖注入在 Spring 中注入资源 Class 实例

How to inject resource Class instance in Spring using Dependency injection

java

spring

dependency-injection

spring-mvc

aws-sdk