JAX-RS @QueryParam Example in Java

In RESTful web services (JAX-RS) @QueryParam annotation will be used to get the query parameters from the URL, Observe carefully, i am saying we will retrieve the parameters only not their values. But in case of @PathParam we will get parameter values directly.

In JAX-RS, you can use @QueryParam annotation to inject URI query parameter into Java method. for example,

/users/query?url=codenuclear.com

In above URI pattern, query parameter is “url=codenuclear.com“, and you can get the url value with @QueryParam(“url”).

Here is the final pom.xml file having required dependencies.


<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>WebServicesJAXRS</groupId>
  <artifactId>WebServicesJAXRS</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <name>WebServicesJAXRS</name>
  <description>Restfull Webservices</description>
  <dependencies>		
		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-server</artifactId>
			<version>1.19</version>
		</dependency>
		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-servlet</artifactId>
			<version>1.19</version>
		</dependency>
  </dependencies>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <warSourceDirectory>WebContent</warSourceDirectory>
          <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

<groupId>WebServicesJAXRS</groupId>

<artifactId>WebServicesJAXRS</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>WebServicesJAXRS</name>

<description>Restfull Webservices</description>

<groupId>com.sun.jersey</groupId>

<artifactId>jersey-server</artifactId>

</dependency>

<groupId>com.sun.jersey</groupId>

<artifactId>jersey-servlet</artifactId>

</dependency>

</dependencies>

<build>

<artifactId>maven-war-plugin</artifactId>

<warSourceDirectory>WebContent</warSourceDirectory>

<failOnMissingWebXml>false</failOnMissingWebXml>

</configuration>

</plugin>

</plugins>

</build>

</project>

Now add Jersey servlet to our deployment descriptor web.xml as front controller.


<?xml version="1.0" encoding="UTF-8"?>  
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
xmlns="http://java.sun.com/xml/ns/javaee"   
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"   
id="WebApp_ID" version="3.0">  
 <servlet>  
    <servlet-name>Jersey REST Service</servlet-name>  
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>  
    <init-param>  
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>com.codenuclear</param-value>  
    </init-param>  
    <load-on-startup>1</load-on-startup>  
  </servlet>  
  <servlet-mapping>  
    <servlet-name>Jersey REST Service</servlet-name>  
    <url-pattern>/rest/*</url-pattern>  
  </servlet-mapping>
</web-app>

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns="http://java.sun.com/xml/ns/javaee"

xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"

id="WebApp_ID" version="3.0">

<servlet-name>Jersey REST Service</servlet-name>

<servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>

<init-param>

<param-name>com.sun.jersey.config.property.packages</param-name>

<param-value>com.codenuclear</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>Jersey REST Service</servlet-name>

<url-pattern>/rest/*</url-pattern>

</servlet-mapping>

</web-app>

@QueryParam example

See a full example of using @QueryParam in JAX-RS.


package com.codenuclear;

import java.util.List;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Response;

@Path("/users")
public class RestServices {

	@GET
	@Path("/query")
	public Response getUsers(
		@QueryParam("from") int from,
		@QueryParam("to") int to,
		@QueryParam("orderBy") List<String> orderBy) {

		return Response
		   .status(200)
		   .entity("getUsers is called, from : " + from + ", to : " + to
			+ ", orderBy" + orderBy.toString()).build();

	}
}

package com.codenuclear;

import java.util.List;

import javax.ws.rs.DefaultValue;

import javax.ws.rs.GET;

import javax.ws.rs.Path;

import javax.ws.rs.QueryParam;

import javax.ws.rs.core.Response;

@Path("/users")

public class RestServices {

@GET

@Path("/query")

public Response getUsers(

@QueryParam("from") int from,

@QueryParam("to") int to,

@QueryParam("orderBy") List<String> orderBy) {

return Response

.status(200)

.entity("getUsers is called, from : " + from + ", to : " + to

+ ", orderBy" + orderBy.toString()).build();

}

Output

URI pattern : “http://localhost:8080/WebServices_JAX_RS/rest/users/query?from=100&to=200&orderBy=age&orderBy=name”

Programmatic Query Parameter

Alternatively, you can get the query parameters grammatically, via “@Context UriInfo“. See equivalent version below :


package com.codenuclear;

import java.util.List;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Response;

@Path("/users")
public class RestServices {

	@GET
	@Path("/query")
	public Response getUsers(@Context UriInfo info) {

		String from = info.getQueryParameters().getFirst("from");
		String to = info.getQueryParameters().getFirst("to");
		List<String> orderBy = info.getQueryParameters().get("orderBy");

		return Response
		   .status(200)
		   .entity("getUsers is called, from : " + from + ", to : " + to
			+ ", orderBy" + orderBy.toString()).build();

	}
}

package com.codenuclear;

import java.util.List;

import javax.ws.rs.DefaultValue;

import javax.ws.rs.GET;

import javax.ws.rs.Path;

import javax.ws.rs.QueryParam;

import javax.ws.rs.core.Response;

@Path("/users")

public class RestServices {

@GET

@Path("/query")

public Response getUsers(@Context UriInfo info) {

String from = info.getQueryParameters().getFirst("from");

String to = info.getQueryParameters().getFirst("to");

List<String> orderBy = info.getQueryParameters().get("orderBy");

return Response

.status(200)

.entity("getUsers is called, from : " + from + ", to : " + to

+ ", orderBy" + orderBy.toString()).build();

}

Output

URI pattern : “http://localhost:8080/WebServices_JAX_RS/rest/users/query?from=300&to=500&orderBy=age&orderBy=name”

@DefaultValue example

@DefaultValue is good for optional parameter.


package com.codenuclear;

import java.util.List;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Response;

@Path("/users")
public class RestServices {

	@GET
	@Path("/query")
	public Response getUsers(@DefaultValue("1000")@QueryParam("from") int from,@DefaultValue("999")@QueryParam("to") int to,@DefaultValue("name")@QueryParam("orderBy") List<String> orderBy) 
	{

		return Response.status(200).entity("getUsers is called, from : " + from + ", to : " + to+ ", orderBy" + orderBy.toString()).build();
	}
}

package com.codenuclear;

import java.util.List;

import javax.ws.rs.DefaultValue;

import javax.ws.rs.GET;

import javax.ws.rs.Path;

import javax.ws.rs.QueryParam;

import javax.ws.rs.core.Response;

@Path("/users")

public class RestServices {

@GET

@Path("/query")

public Response getUsers(@DefaultValue("1000")@QueryParam("from") int from,@DefaultValue("999")@QueryParam("to") int to,@DefaultValue("name")@QueryParam("orderBy") List<String> orderBy)

{