How to use the query parameters in Java Jersey Application?

Question

I am following a tutorial and also used the Stackoverflow question here. Here is my Java class:

package com.crunchify.tutorial;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Consumes;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.UriInfo;
import org.json.simple.JSONObject;

@Path("api")
public class CrunchifyAPI {

    @SuppressWarnings("unchecked")
    @GET
    @Path("/get")
    @Consumes(MediaType.TEXT_PLAIN)
    public String get(
            @DefaultValue("111") @QueryParam("user") int user,
            @Context UriInfo uriInfo
            ) {
        MultivaluedMap<String, String> queryParams = uriInfo.getQueryParameters();
        String nameParam = queryParams.getFirst("user");
        System.out.println("Data Received: " + uriInfo.getRequestUri().getQuery()
                + " | " + nameParam);
        JSONObject obj = new JSONObject();
        obj.put("auth", true);
        String ret = JSONObject.toJSONString(obj);
        return ret;
    }
}

Following is what I am GET'ing from postman:

GET>> localhost/api/get?user=123

Response is:

{"auth":true}

Server console:

Starting Crunchify's Embedded Jersey HTTPServer...

Started Crunchify's Embedded Jersey HTTPServer Successfully !!!
Data Received: ?user=123 | null
User Authenticated: true

I have tried with passing String, Integer etc but nothing works. The uri Info is getting printed correctly and the response back is also fine. The issue is that I am not getting the parameter to be read in Java Code. I will need to pass many other parameters once I am able to get this going. Please suggest. Thanks!!

I am hoping that it will print following in the server console: `Data Received: ?user=123 | 123` Similarly, later on I would like to pass String and (if possible, may be JSON). — Amresh Kadian, Jan 04 '17 at 02:58

score 5 · Answer 1 · answered Dec 01 '17 at 20:36

I think you're trying too hard. As far as I can tell, doing the following should get you what you want if you call localhost/api/get?user=123:

package com.crunchify.tutorial;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Consumes;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.UriInfo;
import org.json.simple.JSONObject;

@Path("api")
public class CrunchifyAPI {

    @SuppressWarnings("unchecked")
    @GET
    @Path("/get")
    @Consumes(MediaType.TEXT_PLAIN)
    public String get(
            @DefaultValue("111") @QueryParam("user") Integer user,
            @Context UriInfo uriInfo
            ) {
        System.out.println("Data Received: " + uriInfo.getRequestUri().getQuery()
                + " | " + name);
        JSONObject obj = new JSONObject();
        obj.put("auth", true);
        String ret = JSONObject.toJSONString(obj);
        return ret;
    }
}

All that extra stuff with the query string isn't needed if all you need is the information passed in the user parameter.

Kalpesh Soni · Answer 2 · 2017-01-04T03:22:37.607

1

@QueryParam("user") int user

the value of that user int should be 123

See https://www.mkyong.com/webservices/jax-rs/jax-rs-queryparam-example/

edited Jan 04 '17 at 03:22

answered Jan 04 '17 at 03:01

Kalpesh Soni

6,169
2
49
53

Yes. I am expecting the following lines to display 123 instead of null: `String nameParam = queryParams.getFirst("user"); System.out.println("Data Received: " + uriInfo.getRequestUri().getQuery() + " | " + nameParam);` I have even tried changing int to String and Integer. Nothing works! – Amresh Kadian Jan 04 '17 at 03:12
try System.out.println(user); – Kalpesh Soni Jan 04 '17 at 03:13
I tried that and it prints 111 instead of null i.e. the default value. `String nameParam = queryParams.getFirst("user"); System.out.println("Data Received: " + uriInfo.getRequestUri().getQuery() + " | " + nameParam); System.out.println(user);` Result: `Data Received: ?user=aaaaa | null 111` --> should be **123** – Amresh Kadian Jan 04 '17 at 03:18
not sure if the issue is mixing two paradims, either use QueryParam or UriInfo, clean up your code, if needed, create two test methods See https://www.mkyong.com/webservices/jax-rs/jax-rs-queryparam-example/ – Kalpesh Soni Jan 04 '17 at 03:22

score 0 · Answer 3 · 2017-09-04T17:32:00.390

0

Well, I think you're having a problem with Java Types.

If your user is an Integer you should pass it to String first if you want to work with a String (Integer.toString() or String.valueof()).

But the way you're passing the parameter is bothering me, I'm not sure if you can pass integers by text plain medi types.

edited Sep 04 '17 at 17:32

answered Sep 04 '17 at 17:06

score 0 · Answer 4 · answered Jun 14 '21 at 12:38

Query parameter mostly used in get rest api for sending data client to server . It can be optional. If it is optional then you can call you api without query parameter(path param is mandatory ) . We can send query parameter in url as

http://localhost:8080/JerseyDemo/rest/user/12?p=10

and you can retrieve this query parameter value on server side as

 @GET
    @Path("/{id}")
    public Response addUser(@PathParam("id") int id,@QueryParam("p") int page) {
        System.out.println("id=" + id+"page="+page);
        String str = "id is=" + id+"page="+page;
        return Response.status(Status.OK).entity(str).build();
   }

For more details for query parameter visit : Query Parameter Example In Jersey

How to use the query parameters in Java Jersey Application?

4 Answers4