JAX-RS - @DefaultValue examples

The annotation @DefaultValue can be used to define a default value for the following request annotations:

• QueryParam
• MatrixParam
• CookieParam
• FormParam
• HeaderParam
• PathParam

The value of the @DefaultValue is used when the corresponding meta-data is not present in the request.

In the following examples, we will quickly see how to use @Default annotation. In each example, we are using JAX-RS Client API to make request to the target resource.

@DefaultValue with @QueryParam

@Path("/")
public class ResourceExample {

  @GET
  @Path("test2")
  public String testQueryParam(
          @DefaultValue("default query param value")
          @QueryParam("queryParam1") String qpString) {
      return "query param value= " + qpString;
  }
}

mvn tomcat7:run

public class ClientUtil {

  public static WebTarget createRequest(String uri) {
      Client client = ClientBuilder.newClient();
      return client.target("http://localhost:8080" + uri);
  }
}

public class QueryParamClient {
  public static void main(String[] args) {

      WebTarget target = ClientUtil.createRequest("/test2");
      target = target.queryParam("queryParam1", 5);
      String response = target.request().get(String.class);
      System.out.printf("response with query param:%n%s%n", response);

      target = ClientUtil.createRequest("/test2");
      response = target.request().get(String.class);
      System.out.printf("response without query param:%n%s%n", response);
  }
}

Output

response with query param:
 response from: http://localhost:8080/test2?queryParam1=5
 PathNum: 2
 query paramMyResource: null

response without query param:
 response from: http://localhost:8080/test2
 PathNum: 2
 query paramMyResource: null

@DefaultValue with @MatrixParam

@Path("/")
public class ResourceExample {

  @GET
  @Path("test3")
  public String test3(
          @DefaultValue("default matrix param value")
          @MatrixParam("matrixParam1") String mpString) {
      return "matrix param value= " + mpString;
  }
}

public class MatrixParamClient {
  public static void main(String[] args) {

      WebTarget target = ClientUtil.createRequest("/test3");
      target = target.matrixParam("matrixParam1", 5);
      String response = target.request().get(String.class);
      System.out.printf("response with matrix param:%n%s%n", response);

      target = ClientUtil.createRequest("/test3");
      response = target.request().get(String.class);
      System.out.printf("response without matrix param:%n%s%n", response);
  }
}

Output

response with matrix param:
 response from: http://localhost:8080/test3;matrixParam1=5
 PathNum: 3
 query paramMyResource: null

response without matrix param:
 response from: http://localhost:8080/test3
 PathNum: 3
 query paramMyResource: null

@DefaultValue with @CookieParam

@Path("/")
public class ResourceExample {

  @GET
  @Path("test4")
  public String test4(
          @DefaultValue("default cookie param value")
          @CookieParam("cookieParam1") String cString) {
      return "cookie value= " + cString;
  }
}

public class CookieParamClient {
  public static void main(String[] args) {

      WebTarget target = ClientUtil.createRequest("/test4");

      String response = target.request()
                              .cookie("cookieParam1", "cookie param value")
                              .get(String.class);
      System.out.printf("response with cookie param:%n%s%n", response);

      //without cookie param
      target = ClientUtil.createRequest("/test4");
      response = target.request().get(String.class);
      System.out.printf("response without cookie param:%n%s%n", response);
  }
}

Output

response with cookie param:
 response from: http://localhost:8080/test4
 PathNum: 4
 query paramMyResource: null

response without cookie param:
 response from: http://localhost:8080/test4
 PathNum: 4
 query paramMyResource: null

@DefaultValue with @FormParam

@Path("/")
public class ResourceExample {

  @POST
  @Path("test5")
  public String test5(
          @DefaultValue("default form param value")
          @FormParam("formParam1") String fString) {
      return "FormParam value= " + fString;
  }
}

public class FormParamClient {
  public static void main(String[] args) {

      WebTarget target = ClientUtil.createRequest("/test5");

      Form form = new Form();
      form.param("formParam1", "form param test value");

      Entity<Form> entity = Entity.entity(form,
              MediaType.APPLICATION_FORM_URLENCODED_TYPE);
      String response = target.request().post(entity, String.class);
      System.out.printf("response with form param:%n%s%n", response);

      target = ClientUtil.createRequest("/test5");
      form = new Form();
      entity = Entity.entity(form, MediaType.APPLICATION_FORM_URLENCODED_TYPE);
      response = target.request().post(entity, String.class);
      System.out.printf("response without form param:%n%s%n", response);
  }
}

Output

response with form param:
FormParam value= form param test value
response without form param:
FormParam value= default form param value

@DefaultValue with @HeaderParam

@Path("/")
public class ResourceExample {

  @GET
  @Path("test6")
  public String test6(
          @DefaultValue("default header param value")
          @HeaderParam("headerParam1") String hString) {
      return "HeaderParam value= " + hString;
  }
}

public class HeaderParamClient {
  public static void main(String[] args) {

      WebTarget target = ClientUtil.createRequest("/test6");
      String response = target.request()
                              .header("headerParam1", "header param value")
                              .get(String.class);
      System.out.printf("response with header param:%n%s%n", response);

      target = ClientUtil.createRequest("/test6");
      response = target.request().get(String.class);
      System.out.printf("response without header param:%n%s%n", response);
  }
}

Output

response with header param:
HeaderParam value= header param value
response without header param:
HeaderParam value= default header param value

@DefaultValue with @PathParam

using @DefaultValue with @PathParam cannot be very useful. That's because a part of the uri path cannot be null for a default value to be assigned.

In following example, Jersey implementation throws '404 Not Found' exception, when a path param is not being used on the client side.

@Path("/")
public class ResourceExample {

  @GET
  @Path("test/{path1}test1")
  public String testPathParam(@DefaultValue("default path value")
                     @PathParam("path1") String path) {
      return "path value= " + path;
  }
}

public class PathParamClient {
  public static void main(String[] args) {
      WebTarget target = ClientUtil.createRequest("/test/test1");
      String response = target.request().get(String.class);
      System.out.println(response);
  }
}

Output

Caused by: javax.ws.rs.NotFoundException: HTTP 404 Not Found
	at org.glassfish.jersey.client.JerseyInvocation.convertToException(JerseyInvocation.java:1020)
	at org.glassfish.jersey.client.JerseyInvocation.translate(JerseyInvocation.java:819)
	at org.glassfish.jersey.client.JerseyInvocation.access$700(JerseyInvocation.java:92)
	at org.glassfish.jersey.client.JerseyInvocation$2.call(JerseyInvocation.java:701)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:228)
	at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:444)
	at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:697)
	at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:420)
	at org.glassfish.jersey.client.JerseyInvocation$Builder.get(JerseyInvocation.java:316)
	at com.logicbig.example.PathParamClient.main(PathParamClient.java:10)
	... 6 more

In the following example, we are using Regex. Skipping a path param on the client side will map to an empty path param:

@Path("/")
public class ResourceExample {

  @GET
  @Path("test/{path1:.*}test2")
  public String testPathParam2(@DefaultValue("default path value")
                              @PathParam("path1") String path) {
      return "path value= " + path;
  }
}

public class PathParamClient2 {
  public static void main(String[] args) {

      WebTarget target = ClientUtil.createRequest("/test/test2");
      String response = target.request().get(String.class);
      System.out.println(response);
  }
}

Output

path value= 

If the value of the @PathParam is not defined in the @Path, then it will always be assigned to a default value:

@Path("/")
public class ResourceExample {

  @GET
  @Path("test1")
  public String testPathParam3(@DefaultValue("10")
                      @PathParam("path1") BigDecimal bd) {
      return "path param Value= " + bd;
  }
}

public class PathParamClient3 {
  public static void main(String[] args) {
      WebTarget target = ClientUtil.createRequest("/test1");
      String response = target.request().get(String.class);
      System.out.println(response);
  }
}

Output

path param Value= 10

Example Project

Dependencies and Technologies Used:

• jersey-container-servlet 2.25.1: Jersey core Servlet 3.x implementation.
• JDK 1.8
• Maven 3.3.9