@RequestParam vs @PathVariable

Question

What is the difference between @RequestParam and @PathVariable while handling special characters?

+ was accepted by @RequestParam as space.

In the case of @PathVariable, + was accepted as +.

Answer 1

• @PathVariable is to obtain some placeholder from the URI (Spring call it an URI Template) — see Spring Reference Chapter 16.3.2.2 URI Template Patterns
• @RequestParam is to obtain an parameter from the URI as well — see Spring Reference Chapter 16.3.3.3 Binding request parameters to method parameters with @RequestParam

If URL http://localhost:8080/MyApp/user/1234/invoices?date=12-05-2013 gets the invoices for user 1234 on December 5th, 2013, the controller method would look like:

@RequestMapping(value="/user/{userId}/invoices", method = RequestMethod.GET)
public List<Invoice> listUsersInvoices(
            @PathVariable("userId") int user,
            @RequestParam(value = "date", required = false) Date dateOrNull) {
  ...
}

Also, request parameters can be optional, and as of Spring 4.3.3 path variables can be optional as well. Beware though: this might change the URL path hierarchy and introduce request mapping conflicts. For example, would /user/invoices provide the invoices for user null or details about a user with ID "invoices"?

Answer 2

@PathVariable - must be placed in the endpoint uri and access the query parameter value from the request
@RequestParam - must be passed as method parameter (optional based on the required property)
 http://localhost:8080/employee/call/7865467

 @RequestMapping(value=“/call/{callId}", method = RequestMethod.GET)
 public List<Calls> getAgentCallById(
            @PathVariable(“callId") int callId,
            @RequestParam(value = “status", required = false) String callStatus) {

    }

http://localhost:8080/app/call/7865467?status=Cancelled

@RequestMapping(value=“/call/{callId}", method = RequestMethod.GET)
public List<Calls> getAgentCallById(
            @PathVariable(“callId") int callId,
            @RequestParam(value = “status", required = true) String callStatus) {

}

Answer 3

@RequestParam is use for query parameter(static values) like: http://localhost:8080/calculation/pow?base=2&ext=4

@PathVariable is use for dynamic values like : http://localhost:8080/calculation/sqrt/8

@RequestMapping(value="/pow", method=RequestMethod.GET)
public int pow(@RequestParam(value="base") int base1, @RequestParam(value="ext") int ext1){
    int pow = (int) Math.pow(base1, ext1);
    return pow;
}

@RequestMapping("/sqrt/{num}")
public double sqrt(@PathVariable(value="num") int num1){
    double sqrtnum=Math.sqrt(num1);
    return sqrtnum;
}

Answer 4

it may be that the application/x-www-form-urlencoded midia type convert space to +, and the reciever will decode the data by converting the + to space.check the url for more info.http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.1

Answer 5

@RequestParam annotation used for accessing the query parameter values from the request. Look at the following request URL:

http://localhost:8080/springmvc/hello/101?param1=10&param2=20

In the above URL request, the values for param1 and param2 can be accessed as below:

public String getDetails(
    @RequestParam(value="param1", required=true) String param1,
        @RequestParam(value="param2", required=false) String param2){
...
}

The following are the list of parameters supported by the @RequestParam annotation:

• defaultValue – This is the default value as a fallback mechanism if request is not having the value or it is empty.
• name – Name of the parameter to bind
• required – Whether the parameter is mandatory or not. If it is true, failing to send that parameter will fail.
• value – This is an alias for the name attribute

@PathVariable

@PathVariable identifies the pattern that is used in the URI for the incoming request. Let’s look at the below request URL:

http://localhost:8080/springmvc/hello/101?param1=10&param2=20

The above URL request can be written in your Spring MVC as below:

@RequestMapping("/hello/{id}")    public String getDetails(@PathVariable(value="id") String id,
    @RequestParam(value="param1", required=true) String param1,
    @RequestParam(value="param2", required=false) String param2){
.......
}

The @PathVariable annotation has only one attribute value for binding the request URI template. It is allowed to use the multiple @PathVariable annotation in the single method. But, ensure that no more than one method has the same pattern.

Also there is one more interesting annotation: @MatrixVariable

http://localhost:8080/spring_3_2/matrixvars/stocks;BT.A=276.70,+10.40,+3.91;AZN=236.00,+103.00,+3.29;SBRY=375.50,+7.60,+2.07

And the Controller method for it

 @RequestMapping(value = "/{stocks}", method = RequestMethod.GET)
  public String showPortfolioValues(@MatrixVariable Map<String, List<String>> matrixVars, Model model) {

    logger.info("Storing {} Values which are: {}", new Object[] { matrixVars.size(), matrixVars });

    List<List<String>> outlist = map2List(matrixVars);
    model.addAttribute("stocks", outlist);

    return "stocks";
  }

But you must enable:

<mvc:annotation-driven enableMatrixVariables="true" >