The Spring MVC framework, i of the most pop frameworks for developing a spider web application inwards Java globe likewise provides several useful annotations to extract information from the incoming asking in addition to mapping the asking to the controller, e.g., @RequestMapping, @RequestParam, in addition to @PathVariable. Even though both @RequestParam and @PathVariable is used to extract values from the HTTP request, in that location is a subtle deviation betwixt them, which makes them a useful enquiry from an interview in addition to spring certification bespeak of view. We'll assay out the subtle deviation between @RequestParam in addition to @PathVaraible inwards this article. As the get upwards suggests, @RequestParam is used to acquire the asking parameters from URL, likewise known equally query parameters, piece @PathVariable extracts values from URI.
For example, if the incoming HTTP asking to recall a mass on topic "Java" is http://localhost:8080/shop/order/1001/receipts?date=12-05-2017, thus you lot tin exercise the @RequestParam annotation to recall the query parameter date in addition to you lot tin exercise @PathVariable to extract the orderId i.e. "1001" equally shown below:
@RequestMapping(value="/order/{orderId}/receipts", method = RequestMethod.GET)
public List listUsersInvoices( @PathVariable("orderId") int order,
@RequestParam(value = "date", required = false) Date dateOrNull) {
...
}
The required=false denotes that the query parameter tin move optional, but the URL must conduct maintain the same URI.
For examples, suppose you lot conduct maintain a spider web application which returns details of orders in addition to trades, in addition to you lot conduct maintain the next URLs:
http://localhost:8080/eportal/orders?id=1001
To conduct maintain the query parameters inwards the higher upwards URLs, you tin exercise the next code inwards the Spring MVC controller:
@RequestMapping("/orders")
public String showOrderDetails(@RequestParam("id") String orderId, Model model){
model.addAttribute("orderId", orderId);
return "orderDetails";
}
If the get upwards of the query parameter is same equally the get upwards of the variable inwards handler's @RequestParam annotated declaration thus you lot tin only exercise @RequestParam without specifying the get upwards of a query parameter, Spring volition automatically derive the value (see REST URIs contains values, e.g. a REST API to recall a mass using ISBN pose out looks similar the following:
URL: http://localhost:8080/book/9783827319333
Now, to extract the value of ISBN pose out from the URI inwards your Spring MVC Controller's handler method, you lot tin exercise @PathVariable annotation equally shown inwards next code:
@RequestMapping(value="/book/{ISBN}", method= RequestMethod.GET)
public String showBookDetails(@PathVariable("ISBN") String id,
Model model){
model.addAttribute("ISBN", id);
return "bookDetails";
}
Similar to @RequestParameter annotation, you lot likewise tin likewise omit the value attribute inwards @PathVariable annotation, if the get upwards of path variable's placeholder inwards the @RequestMapping annotation is same to the variable get upwards inwards the handler method's @PathVariable annotated parameter (see REST amongst Spring).
For example, you lot tin rewrite higher upwards code equally shown below:
@RequestMapping(value="/book/{ISBN}", method= RequestMethod.GET)
public String showBookDetails(@PathVariable String ISBN,
Model model){
model.addAttribute("ISBN", ISBN);
return "bookDetails";
}
Spring MVC provides several useful annotations to map in addition to extract information from the HTTP request, in addition to equally of Spring developer, you lot should move aware of these, e.g. @RequestMapping, @RequestParam, in addition to @PathVariable.
These concepts in addition to annotations are telephone substitution from both Spring MVC interview prospect equally good equally Spring certifications. You volition ever uncovering a couplet of questions based on these concepts.
Btw, if you lot are preparing for Spring Web Certifications, you lot tin likewise banking concern fit out David Mayer's costless Spring Mock Questions to acquire an thought close the marking of questions in addition to format of questions you lot tin human face on existent Spring Web Certification.
1) The @RequestParam is used to extract query parameters piece @PathVariable is used to extract information correct from the URI.
2) @RequestParam is to a greater extent than useful on a traditional spider web application where information is generally passed inwards the query abatements piece @PathVariable is to a greater extent than suitable for RESTful spider web services where URL contains values, e.g. http://localhost:8080/book/9783827319333, hither data, which is ISBN pose out is purpose of URI.
If you lot desire to larn to a greater extent than close how to effectively prepare REST applications using Spring, I advise you lot bring together Eugen Paraschiv's REST amongst Spring course.
It's an online course of pedagogy which volition learn you lot the nitty-gritty of developing both REST API in addition to services for real-world scenarios.
Eugen has extensive experienced inwards developing RESTful spider web services using Spring, in addition to this course of pedagogy is a swell means to tap into his knowledge.
3) @RequestParam annotation tin specify default values if a query parameter is non acquaint or empty past times using a defaultValue attribute, provided the required attribute is false.
4) Spring MVC allows you lot to exercise multiple @PathVariable annotations inwards the same method, provided, no to a greater extent than than i declaration has the same pattern.
That's all close the difference betwixt @PathVariable in addition to @RequestParam in Spring MVC. Even though both are used to extract information from URL, @RequestParam is used to recall query parameters, anything afterwards ? inwards the URL, piece @PathVariable is used to recall values from URI itself. This concept is essential for both traditional spider web application evolution equally good equally developing RESTful Web Services using Spring, thus you lot must pass approximately fourth dimension to sympathize it better.
Other Spring MVC articles you lot may similar to explore
Spring Framework 5: Beginner to Guru
Spring MasterClass from Beginner to Expert
Difference between @RestController in addition to @Controller inwards Spring MVC?
How Spring MVC industrial plant internally?
What is the exercise of DispatcherServlet inwards Spring MVC?
How to enable Spring safety inwards a Java spider web application?
Spring inwards Action past times Craig Walls
Thanks for reading this article thus far. If you lot similar this article, thus delight percentage it amongst your friends in addition to colleagues. If you lot conduct maintain whatever questions, delight driblet me a note.
For example, if the incoming HTTP asking to recall a mass on topic "Java" is http://localhost:8080/shop/order/1001/receipts?date=12-05-2017, thus you lot tin exercise the @RequestParam annotation to recall the query parameter date in addition to you lot tin exercise @PathVariable to extract the orderId i.e. "1001" equally shown below:
@RequestMapping(value="/order/{orderId}/receipts", method = RequestMethod.GET)
public List listUsersInvoices( @PathVariable("orderId") int order,
@RequestParam(value = "date", required = false) Date dateOrNull) {
...
}
The required=false denotes that the query parameter tin move optional, but the URL must conduct maintain the same URI.
How to extract Query Parameters inwards Spring MVC using @RequestParam
Spring MVC is a rich framework to prepare both spider web applications in addition to RESTful spider web services inwards Java. It provides several ways to recall information from the incoming HTTP requests e.g.- Request Parameters
- Path Variables
- Form inputs
Using @RequestParam to acquire Query parameters
In a Spring MVC application, you lot tin exercise the @RequestParam annotation to conduct maintain query parameters inwards Controller's handler methods.For examples, suppose you lot conduct maintain a spider web application which returns details of orders in addition to trades, in addition to you lot conduct maintain the next URLs:
http://localhost:8080/eportal/orders?id=1001
To conduct maintain the query parameters inwards the higher upwards URLs, you tin exercise the next code inwards the Spring MVC controller:
@RequestMapping("/orders")
public String showOrderDetails(@RequestParam("id") String orderId, Model model){
model.addAttribute("orderId", orderId);
return "orderDetails";
}
If the get upwards of the query parameter is same equally the get upwards of the variable inwards handler's @RequestParam annotated declaration thus you lot tin only exercise @RequestParam without specifying the get upwards of a query parameter, Spring volition automatically derive the value (see REST URIs contains values, e.g. a REST API to recall a mass using ISBN pose out looks similar the following:
URL: http://localhost:8080/book/9783827319333
Now, to extract the value of ISBN pose out from the URI inwards your Spring MVC Controller's handler method, you lot tin exercise @PathVariable annotation equally shown inwards next code:
@RequestMapping(value="/book/{ISBN}", method= RequestMethod.GET)
public String showBookDetails(@PathVariable("ISBN") String id,
Model model){
model.addAttribute("ISBN", id);
return "bookDetails";
}
Similar to @RequestParameter annotation, you lot likewise tin likewise omit the value attribute inwards @PathVariable annotation, if the get upwards of path variable's placeholder inwards the @RequestMapping annotation is same to the variable get upwards inwards the handler method's @PathVariable annotated parameter (see REST amongst Spring).
For example, you lot tin rewrite higher upwards code equally shown below:
@RequestMapping(value="/book/{ISBN}", method= RequestMethod.GET)
public String showBookDetails(@PathVariable String ISBN,
Model model){
model.addAttribute("ISBN", ISBN);
return "bookDetails";
}
Spring MVC provides several useful annotations to map in addition to extract information from the HTTP request, in addition to equally of Spring developer, you lot should move aware of these, e.g. @RequestMapping, @RequestParam, in addition to @PathVariable.
These concepts in addition to annotations are telephone substitution from both Spring MVC interview prospect equally good equally Spring certifications. You volition ever uncovering a couplet of questions based on these concepts.
Btw, if you lot are preparing for Spring Web Certifications, you lot tin likewise banking concern fit out David Mayer's costless Spring Mock Questions to acquire an thought close the marking of questions in addition to format of questions you lot tin human face on existent Spring Web Certification.
Difference betwixt @PathVariable in addition to @RequestParam inwards Spring
Now that nosotros sympathize both the deviation equally good equally how to exercise both @RequestParam in addition to @PathVariable inwards Spring MVC application, let's revise the critical deviation betwixt them from an interview perspective.1) The @RequestParam is used to extract query parameters piece @PathVariable is used to extract information correct from the URI.
2) @RequestParam is to a greater extent than useful on a traditional spider web application where information is generally passed inwards the query abatements piece @PathVariable is to a greater extent than suitable for RESTful spider web services where URL contains values, e.g. http://localhost:8080/book/9783827319333, hither data, which is ISBN pose out is purpose of URI.
If you lot desire to larn to a greater extent than close how to effectively prepare REST applications using Spring, I advise you lot bring together Eugen Paraschiv's REST amongst Spring course.
It's an online course of pedagogy which volition learn you lot the nitty-gritty of developing both REST API in addition to services for real-world scenarios.
Eugen has extensive experienced inwards developing RESTful spider web services using Spring, in addition to this course of pedagogy is a swell means to tap into his knowledge.
3) @RequestParam annotation tin specify default values if a query parameter is non acquaint or empty past times using a defaultValue attribute, provided the required attribute is false.
4) Spring MVC allows you lot to exercise multiple @PathVariable annotations inwards the same method, provided, no to a greater extent than than i declaration has the same pattern.
That's all close the difference betwixt @PathVariable in addition to @RequestParam in Spring MVC. Even though both are used to extract information from URL, @RequestParam is used to recall query parameters, anything afterwards ? inwards the URL, piece @PathVariable is used to recall values from URI itself. This concept is essential for both traditional spider web application evolution equally good equally developing RESTful Web Services using Spring, thus you lot must pass approximately fourth dimension to sympathize it better.
Other Spring MVC articles you lot may similar to explore
Spring Framework 5: Beginner to Guru
Spring MasterClass from Beginner to Expert
Difference between @RestController in addition to @Controller inwards Spring MVC?
How Spring MVC industrial plant internally?
What is the exercise of DispatcherServlet inwards Spring MVC?
How to enable Spring safety inwards a Java spider web application?
Spring inwards Action past times Craig Walls
Thanks for reading this article thus far. If you lot similar this article, thus delight percentage it amongst your friends in addition to colleagues. If you lot conduct maintain whatever questions, delight driblet me a note.