This is a big topic. The Spring reference doc devotes multiple chapters to it. I recommend reading the ones on Aspect-Oriented Programming and Transactions, as Spring’s declarative transaction support uses AOP at its foundation. But at a very high level, Spring creates proxies for classes that declare @Transactional on the class itself or on members. … Read more
Both @Autowired (or @Inject) and @Resource work equally well. But there is a conceptual difference or a difference in the meaning @Resource means get me a known resource by name. The name is extracted from the name of the annotated setter or field, or it is taken from the name-Parameter. @Inject or @Autowired try to … Read more
@RequestMapping(value = “/files/{file_name}”, method = RequestMethod.GET) public void getFile( @PathVariable(“file_name”) String fileName, HttpServletResponse response) { try { // get your file as InputStream InputStream is = …; // copy it to response’s OutputStream org.apache.commons.io.IOUtils.copy(is, response.getOutputStream()); response.flushBuffer(); } catch (IOException ex) { log.info(“Error writing file to output stream. Filename was ‘{}'”, fileName, ex); throw new RuntimeException(“IOError … Read more
Change your return type to ResponseEntity<>, and then you can use the below for 400: return new ResponseEntity<>(HttpStatus.BAD_REQUEST); And for a correct request: return new ResponseEntity<>(json,HttpStatus.OK); After Spring 4.1 there are helper methods in ResponseEntity which could be used as: return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(null); and return ResponseEntity.ok(json);
If you know that you’ll want to see all Comments every time you retrieve a Topic then change your field mapping for comments to: @OneToMany(fetch = FetchType.EAGER, mappedBy = “topic”, cascade = CascadeType.ALL) private Collection<Comment> comments = new LinkedHashSet<Comment>(); Collections are lazy-loaded by default, take a look at this if you want to know more.
So, finally I realized what the problem is. It is not a Jackson configuration issue as I doubted. Actually the problem was in ApplesDO Class: public class ApplesDO { private String apple; public String getApple() { return apple; } public void setApple(String apple) { this.apple = apple; } public ApplesDO(CustomType custom) { //constructor Code } … Read more
The Spring core technologies reference documentation describes what beans are. Per the Introduction to the Spring IoC Container and Beans section (where “IoC” means “inversion of control”): In Spring, the objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. A bean is an object … Read more
Try using this in your properties file: logging.level.org.hibernate.SQL=DEBUG logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE
Good question, although not a trivial one to answer. Propagation Defines how transactions relate to each other. Common options: REQUIRED: Code will always run in a transaction. Creates a new transaction or reuses one if available. REQUIRES_NEW: Code will always run in a new transaction. Suspends the current transaction if one exists. The default value … Read more
I think transactions belong on the service layer. It’s the one that knows about units of work and use cases. It’s the right answer if you have several DAOs injected into a service that need to work together in a single transaction.