Custom provider for http header values as a Spring Bean - java

I have big legacy project with a lot of code and logic.
I have many similar methods in my controller:
public void someEndpoint(
#RequestHeader("flowId") String flowId,
#RequestHeader("someAnotherParam") String someAnotherParam,
#RequestHeader("customerId") String customerId
) {
//pass all arguments to services
}
Every controller method has this three arguments.
This three arguments are passed to another services, and next to another services and another services as method argument.
Whole code is a little messy from this reason.These three arguments are everywhere.
Can I write something like a provider for this three parameter? Some service like:
#Service
class RequestContextProvider {
public RequestContext getRequestContext() {
//some logic
}
}
class RequestContext {
String flowId,
String someAnotherParam,
String customerId
}
And how to do that using spring?

You can use RequestContextHolder class as below:
RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
HttpServletRequest request = ((ServletRequestAttributes)requestAttributes).getRequest();
String flowId = request.getHeader("flowId");

Related

Check if a controller has a #RequestHeader dynamically (in a test)

Using SpringBoot I managed to get the list of all controllers dynamically (in a test) using RequestMappingHandlerMapping, but I cannot check if the controller uses the #RequestHeader("language") or not. Is there a way to retrieve this information?
I don't think it's possible from RequestMappingHandlerMapping.
Thanks.
public void randomApi(#PathVariable("user") String user,
#RequestHeader("language") String language){...}
RequestMappingHandlerMapping represents all controller methods, you have to get a particular controller method that you are interested from it first. The easiest way to do it is first give a name to the controller method such as GetRandomApi :
#GetMapping(name = "GetRandomApi" , value= "/random")
public void randomApi(#PathVariable("user") String user, #RequestHeader("language") String language){
}
and then get the controller method by this name :
HandlerMethod hm = mapping.getHandlerMethodsForMappingName("GetRandomApi").get(0);
Please note HandlerMethod represents a controller method and I assume you only has one controller method with this name.
To check if this controller method has a parameter which is annotated with #RequestHeader , you can do something likes:
for( MethodParameter param : hm.getMethodParameters()){
RequestHeader requestHeader = param.getParameterAnnotation(RequestHeader.class);
if(requestHeader != null) {
System.out.println(String.format("parameter index %s is annotated with #RequestHeader with the value %s",
param.getParameterIndex(),
requestHeader.value()));
}
}

How to split classes to use serveral #Controller

I am learning spring boot, and i developed the below simple example. I would like to annotate a class as Controller using #Controller. this class has constructor and I want to have access to GreetingFromDeuController as shown:
http://localhost:8080:/GreetingFromDeuController?str = "hi"
the error i am receiving is
#RequestMapping is not applicable on a constructor
please let me know how to solve.
code:
#Controller
#RequestMapping("/GreetingFromDeuController")
public class GreetingFromDeuController {
private String str;
#RequestMapping("/GreetingFrom/deu")
GreetingFromDeuController(#RequestParam(value = "str") String str) {
this.str = str;
}
#RequestMapping("/GreetingFromDeuController")
public String getGreetingFromDeu() {
return this.str;
}
}
First of all your constructor gets initialize much before you hit your URL. So you need to work on your design or tell me your business requirement and I will try to provide you a solution. My refactor code solution will help you to achieve that in two steps. First hit POST method which will do work on setting variable and then subsequent hits of GET method will return that set value.
We can refactor code like below. It will explain use of RequestMapping on method and class.
Considering we have to write two API, one for reading and one for writing.
URLS :
1. POST http://localhost:8080/example/greetings (in request body send {str:'hi'})
2. GET http://localhost:8080/example/greetings
#Controller
#RequestMapping("/example")
public class GreetingFromDeuController {
private String str;
#RequestMapping(value="/greetings" , method = RequestMethod.POST)
public void setGreetingFromDeu(#RequestBody(value = "str") String str)
{
this.str = str;
}
#RequestMapping(value="/greetings" , method = RequestMethod.GET)
public String getGreetingFromDeu()
{
return this.str;
}
}
The #RequestMapping documentation says:
Annotation for mapping web requests onto methods in request-handling
classes with flexible method signatures.
Then you can not do that, if you want to initialize your variables or whatever you can use several ways:
1.- Use #PostConstruct
#PostContruct
public void init() {
this.str = "Anything";
}
2.- Use a simple request to set anything only
#RequestMapping(value="/refresh/anythings", method = RequestMethod.PUT)
public void refresh(#RequestBody(value = "str") String str) {
this.str = str;
}
3.- Use #Value
In application.properties / application.yaml
properties.str = anything
In the Controller
#Value("${properties.str:default}") // by default str is "default"
public String str;
#RequestMapping(value="/greetings" , method = RequestMethod.GET)
public String getGreetingFromDeu() {
return this.str;
}
As far I am concerned, #RequestMapping is not meant for constructors. It should be used for annotating methods or classes. Methods that are responsible for handling requests.
#RequestMapping should be used to map request with endPoint. which can be used as class level and method level.
You can use #RestController (improved from #Controller see difference).
The ideal flow for Spring Boot is Controller -> Service -> Repository
Controller -> maps request with endPoint and return response
Service -> perform business logic
Repository -> Handle database operation
Example
#RestController
#RequestMapping("/api")
public class GreetingController {
#Autowired GreetinService greetingService;
// Request http://localhost:8080/api/GreetingFrom
#GetMapping("/GreetingFrom")
public ResponseEntity<String> GreetingRequestParam(#RequestParam(value = "name") String name) {
greetingService.performBusinessLogic(name);
return new ResponseEntity<String>("Greetings from "+name,HttpStatus.OK);
}
// Request http://localhost:8080/api/GreetingFrom/user2121
#GetMapping("/GreetingFrom/{name}")
public ResponseEntity<String> GreetingPathVariable(#PathVariable(value = "name") String name) {
return new ResponseEntity<String>("Greetings from "+name,HttpStatus.OK);
}
}

Spring restful API, is there a method being used like router to get other method's end points or URL?

#RequestMapping("/accounts")
public class controller {
#GetMapping("/get/{id}")
public final ResponseEntity<?> getHandler(){
}
#PostMapping(value = "/create")
public final ResponseEntity<?> createHandler(){
/*
trying to use some spring library methods to get the url string of
'/accounts/get/{id}' instead of manually hard coding it
*/
}
}
This is the mock code, now I am in createHandler, after finishing creating something, then I want to return a header including an URL string, but I don't want to manually concat this URL string ('/accounts/get/{id}') which is the end point of method getHandler(), so I am wondering if there is a method to use to achieve that? I know request.getRequestURI(), but that is only for the URI in the current context.
More explanation: if there is some library or framework with the implementation of route:
Routes.Accounts.get(1234)
which return the URL for the accounts get
/api/accounts/1234
The idea is, that you don't need to specify get or create (verbs are a big no-no in REST).
Imagine this:
#RequestMapping("/accounts")
public class controller {
#GetMapping("/{id}")
public final ResponseEntity<?> getHandler(#PathVariable("id") String id) {
//just to illustrate
return complicatedHandlerCalculation(id).asResponse();
}
#PostMapping
public final ResponseEntity<?> createHandler() {
//return a 204 Response, containing the URI from getHandler, with {id} resolved to the id from your database (or wherever).
}
}
This would be accessible like HTTP-GET: /api/accounts/1 and HTTP-POST: /api/accounts, the latter would return an URI for /api/accounts/2 (what can be gotten with HTTP-GET or updated/modified with HTTP-PUT)
To resolve this URI, you could use reflection and evaluate the annotations on the corresponding class/methods like Jersey does.
A Spring equivalent could be:
// Controller requestMapping
String controllerMapping = this.getClass().getAnnotation(RequestMapping.class).value()[0];
and
//Method requestMapping
String methodMapping = new Object(){}.getClass().getEnclosingMethod().getAnnotation(GetMapping.class).value()[0];
taken from How do i get the requestmapping value in the controller?

How to map a request in Spring MVC to a Java Object

I'm new to Spring, and since Spring provides many ways to map an HTTP request to Java objects, I'm hoping someone could advice me how to resolve this:
I have a client that sends a request having
ContentType: application/x-www-form-urlencoded
Some of the request parmeters have names such as
"form_data[orderStatus]", "form_data[orderNumber]", etc'
I have no control over this client!
I have a java class (#Component) called MyOrder which looks as follows:
#component
#Scope("prototpe")
public class MyOrder {
private String orderStatus;
private String orderNumber;
//etc'
public void setOrderStatus(String orderStatus) {
this.orderStatus = orderStatus;
}
//public setter for all other properties, as the above
}
What is the simplest way to create an instance of MyOrder
populated with all values of all "form_data[]", so that I can have a controller method having a signature that includes a MyOrder parameter, such as:
public ModelAndView saveNewOrder( #RequestParam("foo") String foo,
#ModelAttribute("myOrder") MyOrder anOrder) {
//... impl'n here
}
The best solution I could think of was to use a Web Filter which would flaten request params names such as "form_data[attrib1]" to "attrib1", and then Spring would do all the work of populating the MyOrder instance.
One disadvantage of this is that the request may have both "form_data[attrib1]" and "attrib1" parameters. For example:
form_data[orderStatus]=ok
orderStatus=fail
In this case i want MyOrder.orderStatus to have the value "ok".
Any good way of utilizing Spring create MyOrder from the request?
As an alternative, that does not use the class MyOrder, is there a way to have Spring map all the form_data[] parameters and their values to a map, so that i can have the controller method below?
public ModelAndView saveNewOrder( #RequestParam("foo") String foo,
<some annotation> #Map<String,String> formFieldsOfAnOrder) {
//... impl'n here
orderStatus = formFieldsOfAnOrder.get("orderStatus");
//or at least:
orderStatus = formFieldsOfAnOrder.get("form_data[orderStatus]");
}

Spring MVC: bind request attribute to controller method parameter

In Spring MVC, it is easy to bind request parameter to method paramaters handling the request. I just use #RequestParameter("name"). But can I do the same with request attribute? Currently, when I want to access request attribute, I have to do following:
MyClass obj = (MyClass) request.getAttribute("attr_name");
But I really would like to use something like this instead:
#RequestAttribute("attr_name") MyClass obj
Unfortunately, it doesn't work this way. Can I somehow extend Spring functionality and add my own "binders"?
EDIT (what I'm trying to achieve): I store currently logged user inside request attribute. So whenever I want to access currently logged user (which is pretty much inside every method), I have to write this extra line user = (User) request.getAttribute("user");. I would like to make it as short as possible, preferably inject it as a method parameter. Or if you know another way how to pass something across interceptors and controllers, I would be happy to hear it.
Well, I finally understood a little bit how models work and what is #ModelAttribute for. Here is my solution.
#Controller
class MyController
{
#ModelAttribute("user")
public User getUser(HttpServletRequest request)
{
return (User) request.getAttribute("user");
}
#RequestMapping(value = "someurl", method = RequestMethod.GET)
public String HandleSomeUrl(#ModelAttribute("user") User user)
{
// ... do some stuff
}
}
The getUser() method marked with #ModelAttribute annotation will automatically populate all User user parameters marked with #ModelAttribute. So when the HandleSomeUrl method is called, the call looks something like MyController.HandleSomeUrl(MyController.getUser(request)). At least this is how I imagine it. Cool thing is that user is also accessible from the JSP view without any further effort.
This solves exactly my problem however I do have further questions. Is there a common place where I can put those #ModelAttribute methods so they were common for all my controllers? Can I somehow add model attribute from the inside of the preHandle() method of an Interceptor?
Use (as of Spring 4.3) #RequestAttribute:
#RequestMapping(value = "someurl", method = RequestMethod.GET)
public String handleSomeUrl(#RequestAttribute User user) {
// ... do some stuff
}
or if the request attribute name does not match the method parameter name:
#RequestMapping(value = "someurl", method = RequestMethod.GET)
public String handleSomeUrl(#RequestAttribute(name="userAttributeName") User user) {
// ... do some stuff
}
I think what you are looking for is:
#ModelAttribute("attr_name") MyClass obj
You can use that in the parameters for a method in your controller.
Here is a link a to question with details on it What is #ModelAttribute in Spring MVC?
That question links to the Spring Documentation with some examples of using it too. You can see that here
Update
I'm not sure how you are setting up your pages, but you can add the user as a Model Attribute a couple different ways. I setup a simple example below here.
#RequestMapping(value = "/account", method = RequestMethod.GET)
public ModelAndView displayAccountPage() {
User user = new User(); //most likely you've done some kind of login step this is just for simplicity
return new ModelAndView("account", "user", user); //return view, model attribute name, model attribute
}
Then when the user submits a request, Spring will bind the user attribute to the User object in the method parameters.
#RequestMapping(value = "/account/delivery", method = RequestMethod.POST)
public ModelAndView updateDeliverySchedule(#ModelAttribute("user") User user) {
user = accountService.updateDeliverySchedule(user); //do something with the user
return new ModelAndView("account", "user", user);
}
Not the most elegant, but works at least...
#Controller
public class YourController {
#RequestMapping("/xyz")
public ModelAndView handle(
#Value("#{request.getAttribute('key')}") SomeClass obj) {
...
return new ModelAndView(...);
}
}
Source : http://blog.crisp.se/tag/requestattribute
From spring 3.2 it can be done even nicer by using Springs ControllerAdvice annotation.
This then would allow you to have an advice which adds the #ModelAttributes in a separate class, which is then applied to all your controllers.
For completeness, it is also possible to actually make the #RequestAttribute("attr-name") as is.
(below modified from this article to suit our demands)
First, we have to define the annotation:
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.PARAMETER)
public #interface RequestAttribute {
String value();
}
Then we need a [WebArgumentResolver] to handle what needs to be done when the attribute is being bound
public class RequestAttributeWebArgumentResolver implements WebArgumentResolver {
public Object resolveArgument(MethodParameter methodParameter, NativeWebRequest nativeWebRequest) throws Exception {
// Get the annotation
RequestAttribute requestAttributeAnnotation = methodParameter.getParameterAnnotation(RequestAttribute.class);
if(requestAttributeAnnotation != null) {
HttpServletRequest request = (HttpServletRequest) nativeWebRequest.getNativeRequest();
return request.getAttribute(requestAttributeAnnotation.value);
}
return UNRESOLVED;
}
}
Now all we need is to add this customresolver to the config to resolve it:
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="customArgumentResolver">
<bean class="com.sergialmar.customresolver.web.support.CustomWebArgumentResolver"/>
</property>
</bean>
And we're done!
Yes, you can add your own 'binders' to the request attribute - see spring-mvc-3-showcase, or use #Peter Szanto's solution.
Alternatively, bind it as a ModelAttribute, as recommended in other answers.
As it's the logged-in user that you want to pass into your controller, you may want to consider Spring Security. Then you can just have the Principle injected into your method:
#RequestMapping("/xyz")
public String index(Principal principle) {
return "Hello, " + principle.getName() + "!";
}
In Spring WebMVC 4.x, it prefer implements HandlerMethodArgumentResolver
#Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.getParameterAnnotation(RequestAttribute.class) != null;
}
#Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
return webRequest.getAttribute(parameter.getParameterAnnotation(RequestAttribute.class).value(), NativeWebRequest.SCOPE_REQUEST);
}
}
Then register it in RequestMappingHandlerAdapter

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