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Content-Type is missing with Spring GET/POST method

I am new to Spring and I am trying to do the basic GET and POST method.
This is how I am trying to do the methods:
#RestController
public class DeskController {
#Autowired
private DeskDao dao;
#GetMapping("desks")
public List<Desk> getDesks() {
System.out.println(dao.findById(1L));
return dao.findAll();
}
#PostMapping("desks")
public Desk save(#RequestBody #Valid Desk desk) {
Desk deskObj = dao.save(desk);
System.out.println(deskObj);
return deskObj;
}
When I am calling the POST method like this I get the pring with the actual object that I had called it with so it is working fine, but I also get this error:
javax.ws.rs.ProcessingException: Content-Type is missing
And when trying to call GET it tells me that:
org.springframework.web.HttpRequestMethodNotSupportedException: Request method 'GET' not supported
I am aware that I have not included the whole code, but I will add what is needed to resolve this error since there are a lot of classes.
My questions are, what do I do against the first error and why is GET method not supported?

Two things you need to change :
Use a / to indicate that for this path you will perform an
operation. For eg : (/desks)
Use the annotation #Consumes to
indicate that this method accepts the payload in particular format. For eg : #Consumes(MediaType.APPLICATION_JSON) annotated over your save() method.

#SessionAttributes not working properly for consecutive get requests

Before asking question first i describe the scenario. I have multiple servlet contexts. suppose /**book**/review url is corresponding to book-servlet.xml and /**report**/update corresponds to report-servlet.xml.
Here are two controllers
#Controller
#SessionAttributes(BookController.COMMAND_NAME)
public class BookController {
public static final String COMMAND_NAME = "login";
#GetMapping("/book/review")
public String show(ModelMap modelMap) {
modelMap.put(COMMAND_NAME, getBook());
return "redirects:" + "/report/update"; //it redirects to second controller method
}
}
#Controller
#SessionAttributes(ReportController.COMMAND_NAME)
public class ReportController {
public static final String COMMAND_NAME = "report";
#GetMapping("/report/update")
public String show(ModelMap modelMap) {
modelMap.put(COMMAND_NAME, getReport());
return "redirects:" + "/report/done";
}
}
Observe this two controller. When i put getBook() in model it stores this object in session after method excution since #SessionAttributes(BookController.COMMAND_NAME) is added above class definition. But, after redirection to /report/update (different servlet context) we are also trying to put getReport() in model. And after handler method excution spring should put the object in session as it does for first case.Unfortunately for second controller it doesn't store it in session.
My question is if the first controller method can successfully save it in session why the second controller can't? Or is it for servlet context switching / multiple get requests or something like this. Please i need to know the reason it behaves weirdly. I am now totally confused about #SessionAttributes. It should work same for both controllers.

After studying on this i found that it is wise to use RedirectAttributes for this type of redirect scenario. Cause ModelMap is intended for scenario where you use this ModelMap attributes to rendering a view. And FlashAttribute will survive after immediate redirection to another handler method and then be erased. So, i did my solution using RedirectAttrinute support from spring.

Configure Spring interceptor for controllers only

I'm trying to configure a Spring interceptor for controllers only in the following way. For the beginning I want to exclude all the requests starting with /swagger. I try to do it in the following way:
registry.addInterceptor(myInterceptor).addPathPatterns("/**").excludePathPatterns("/swagger**");
However, interceptor gets fired. Where is a mistake?
Maybe, there is an alternative solution with #ControllerAdvice. But I need to get request headers, so I guess it doesn't fit my needs.
Thanks for any help!

Try to use "/swagger*/**" or "/swagger*" instead of "/swagger**"

I solved the problem in the following way:
#ControllerAdvice
public class SomeAdvice {
#ModelAttribute
public void token(HttpServletRequest request) {
// getting headers and setting the attribute in the request
request.setAttribute("theAttribute", new SomeObject());
}
}
And then I get the request attribute in a controller this way:
public void someMethod(#RequestAttribute("theAttribute") SomeObject someObject) {
// some logic goes here
}
P.S. And one more note. If you're using Swagger you'll get into the trouble as Swagger will consider this attribute as controller method parameter. To ignore it you can use the following snapshot of configuration:
.ignoredParameterTypes(SomeObject.class);

#ModelAttribute dependency check not working properly

The #ModelAttribute methods in the controller are
#ModelAttribute("command")
public A getA() {
...
}
#ModelAttribute
public void prepareData(#ModelAttribute("command") A a) {
...
}
We are using Spring 4.2.6 version and As per Spring forum This issue has been resolved in 4.1.0 version of spring. When I deploy the project sometimes getA() is executing before prepareData and sometimes prepareData() is executing before getA(), but according to jira for above issue, it has been fixed in all the spring versions starting from 4.1.0. Could you please suggest am I missing anything here.

You should mark only 'preparedData' with #ModelAttribute not both. Marking so means it would get executed before any requests or controller method is called.
So if 'getA' is your controller method and you want to preprocess 'A' before it being called (at getA) your methods should be something like this
public A getA(#ModelAttribute("command") A a) { ... }
#ModelAttribute("command")
public A prepareData() {
return new A();//or some other way you want to populate values of A
}

How to implement Spring's 3.1 MvcAnnotationDriven?

This is the code example from Spring 3.1 Spring Source Blog: From XML to #Configuration I'm trying to implement in my application (which was done in Spring 2.0 not by me so it's lot of learning).
#FeatureConfiguration
class MvcFeatures {
#Feature
public MvcAnnotationDriven annotationDriven(ConversionService conversionService) {
return new MvcAnnotationDriven().conversionService(conversionService)
.argumentResolvers(new CustomArgumentResolver());
}
// ...
}
However, I can't understand the point of .argumentResolvers(new CustomArgumentResolver()) and their CustomArgumentResolver looks like bellow. What's the point of it?
public class CustomArgumentResolver implements WebArgumentResolver {
#Override
public Object resolveArgument(MethodParameter param, NativeWebRequest request) throws Exception {
RequestAttribute attr = param.getParameterAnnotation(RequestAttribute.class);
if (attr != null) {
return request.getAttribute(attr.value(), WebRequest.SCOPE_REQUEST);
} else {
return WebArgumentResolver.UNRESOLVED;
}
}
}

To add to #GaryF's answer, and to clarify some points, Spring 2.5 introduced annotated controllers, which replaced the old interface-style controllers of Spring 2.0. These new controllers have methods with no fixed parameters - the method declares the parameters that it needs to do its job, and nothing more.
For example, say a controller method needed one thing to do its job - a request parameter that contains the ID of an object from the database. In Spring 2.0, you would need to implement something like AbstractController.handleRequestInternal(), e.g
protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) {
String id = request.getParameter("id");
MyThing obj = getObjById(id);
//... do stuff and return ModelAndView
}
Spring 2.5 made that easier:
#RequestMapping
public ModelAndView handle(String id) {
MyThing obj = getObjById(id);
//... do stuff and return ModelAndView
}
Here, we only declare parameters for the stuff we need.
So far so good, but this is where a custom WebArgumentResolver comes in. Say I want to remove the getObjById from my controller altogether, because maybe I think it clutters up the code, and maybe it's used across many other controller methods. Instead, I want to do this:
#RequestMapping
public ModelAndView handle(MyThing id) {
//... do stuff and return ModelAndView
}
It's even simpler, and has a bare minimum of boilerplate code. A custom WebArgumentResolver can be registered with the app-context which recognises parameters of type MyThing, and knows how to extract the information from the request. Spring invokes that resolver, and passes the result to the controller method.
Custom resolvers aren't commonly used, but can be very handy in the right situation.
The example in your question uses CustomArgumentResolver to resolve the example's custom RequestAttribute class. The resolver pulls out request attributes and binds them to RequestAttribute objects, so that they can be declared as controller method parameters.

WebArgumentResolvers are a way for you to specify how the parameters of MVC-mapped methods should be resolved. If you'd like to use a custom object as a parameter for an MVC-mapped method, Spring tries to figure out how make sense of it in it's own way. Typically this would happen through binding, where some http parameters you submit match up with the fields of the object and Spring matches them up and creates a new object for you.
If you ever have a situation where the submitted parameters don't match up quite so neatly with your method parameters, WebArgumentResolvers are there to fill in the gap: you provide custom logic so Spring doesn't have to figure it out.
In your example, param is one such parameter to be matched up. This piece of custom code first checks if the parameter has an #RequestAttribute annotation. If it does, then the custom code pulls the value from that object and looks it up as an attribute on the http request, returning it. It it does not have that annotation, then the method returns the UNRESOLVED value, which simply indicates that this WebArgumentResolver doesn't know anything about this particular parameter and Spring should try a different method (such as binding).