how to capture multiple parameters using @RequestParam using spring mvc?

Question

Suppose a hyperlink is clicked and an url is fired with the following parameter list myparam=myValue1&myparam=myValue2&myparam=myValue3 . Now how can I

Answer 1

As of Spring 3.0, you can also use MultiValueMap to achieve this:

A rudimentary example would be:

public String someMethod(@RequestParam MultiValueMap<String,String> params) {

    final Iterator<Entry<String, List<String>>> it = params.entrySet().iterator();

    while(it.hasNext()) {
        final String k = it.next().getKey();
        final List<String> values = it.next().getValue();
    }

    return "dummy_response";

}

Answer 2

Spring mvc can support List<Object>, Set<Object> and Map<Object> param, but without @RequestParam.

Take List<Object> as example, if your object is User.java, and it like this:

public class User {
    private String name;
    private int age;

    // getter and setter
}

And you want pass a param of List<User>, you can use url like this

http://127.0.0.1:8080/list?users[0].name=Alice&users[0].age=26&users[1].name=Bob&users[1].age=16

Remember to encode the url, the url after encoded is like this:

http://127.0.0.1:8080/list?users%5B0%5D.name=Alice&users%5B0%5D.age=26&users%5B1%5D.name=Bob&users%5B1%5D.age=16

Example of List<Object>, Set<Object> and Map<Object> is displayed in my github.

Answer 3

It seems you can't get

Map<String,String>

because all your params have same name "myparam"

Try this instead:

public ModelAndView method(@RequestParam("myparam") List<String> params) { }

Answer 4

To get all parameters at once try this:

public ModelAndView postResultPage(@RequestParam MultiValueMap<String, String> params)

This feature is described in the @RequestParam java doc (3. Paragraph):

Annotation which indicates that a method parameter should be bound to a web request parameter. Supported for annotated handler methods in Servlet and Portlet environments.

If the method parameter type is Map and a request parameter name is specified, then the request parameter value is converted to a Map assuming an appropriate conversion strategy is available.

If the method parameter is Map<String, String> or MultiValueMap<String, String> and a parameter name is not specified, then the map parameter is populated with all request parameter names and values.

Answer 5

If anyone is trying to do the same in Spring Boot, use RequestBody in place of RequestParam

Answer 6

@RequestMapping(value = "users/newuser", method = RequestMethod.POST)   
public String saveUser(@RequestParam Map<String,String> requestParams) throws Exception{
   String userName=requestParams.get("email");
   String password=requestParams.get("password");

   //perform DB operations

   return "profile";
}

You could use RequestParam in the above mentioned manner.