How to add an instance of a resource class to Spring using dependency injection
I am new to Spring. There is a case for which I wrote a class that implements the AutoCloseable interface. Now I want to use it as dependency injection.
I am worried that if I use @Autowired and later use it in a function, will Spring automatically close the resource object upon completion of the scope or any exception?
@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
}
}
Now I do it like this. Please tell me if this is normal or the resource is leaking. If so, what can I do?
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For Spring managed beans, you can either implement the DisposableBean interface or use the @PreDestroy annotation. Spring will call destroy method when destroying the application context.
If you need to create and close an object on every method call you should use try-with-resources
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AutoCloseable will never be closed by Spring unless you use try-with-resources
or explicitly callclose()
void close () throws an exception Closes this resource, discarding any underlying resources. This method is called automatically for objects managed by a try-with-resources statement.
from javadoc
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