Annotations for Field and Bean Properties of Resource Classes (original) (raw)

Annotation	Description
@Context	Injects information into a class field, bean property, or method parameter
@CookieParam	Extracts information from cookies declared in the cookie request header
@FormParam	Extracts information from a request representation whose content type is application/x-www-form-urlencoded
@HeaderParam	Extracts the value of a header
@MatrixParam	Extracts the value of a URI matrix parameter
@PathParam	Extracts the value of a URI template parameter
@QueryParam	Extracts the value of a URI query parameter

Extracting Path Parameters

URI path templates are URIs with variables embedded within the URI syntax. The@PathParam annotation lets you use variable URI path fragments when you call a method.

The following code snippet shows how to extract the last name of an employee when the employee’s email address is provided:

@Path(/employees/"{firstname}.{lastname}@{domain}.com") public class EmpResource {

@GET
@Produces("text/xml")
public String getEmployeelastname(@PathParam("lastname") String lastName) {
 ...
}

}

In this example, the @Path annotation defines the URI variables (or path parameters){firstname} , {lastname}, and {domain}. The @PathParam in the method parameter of the request method extracts the last name from the email address.

If your HTTP request is GET /employees/john.doe@example.com, the value “doe” is injected into{lastname}.

You can specify several path parameters in one URI.

You can declare a regular expression with a URI variable. For example, if it is required that the last name must consist only of lower and upper case characters, you can declare the following regular expression:

@Path(/employees/{"firstname}.{lastname[a-zA-Z]*}@{domain}.com")

If the last name does not match the regular expression, a 404 response is returned.

Extracting Query Parameters

Use the @QueryParam annotation to extract query parameters from the query component of the request URI.

For instance, to query all employees who have joined within a specific range of years, use a method signature like the following:

@Path(/employees/") @GET public Response getEmployees( @DefaultValue("2002") @QueryParam("minyear") int minyear, @DefaultValue("2010") @QueryParam("maxyear") int maxyear) {...}

This code snippet defines two query parameters, minyear and maxyear. The following HTTP request would query for all employees who have joined between 1999 and 2009:

GET /employees?maxyear=2009&minyear=1999

The @DefaultValue annotation defines a default value, which is to be used if no values are provided for the query parameters. By default, JAX-RS assigns a null value for Object values and zero for primitive data types. You can use the @DefaultValue annotation to eliminate null or zero values and define your own default values for a parameter.

Extracting Form Data

Use the @FormParam annotation to extract form parameters from HTML forms. For example, the following form accepts the name, address, and manager’s name of an employee:

Employee name: Employee address: Manager name:

Use the following code snippet to extract the manager name from this HTML form:

@POST @Consumes("application/x-www-form-urlencoded") public void post(@FormParam("managername") String managername) { // Store the value ... }

To obtain a map of form parameter names to values, use a code snippet like the following:

@POST @Consumes("application/x-www-form-urlencoded") public void post(MultivaluedMap<String. String> formParams) { // Store the message }

Extracting the Java Type of a Request or Response

The javax.ws.rs.core.Context annotation retrieves the Java types related to a request or response.

The javax.ws.rs.core.UriInfo interface provides information about the components of a request URI. The following code snippet shows how to obtain a map of query and path parameter names to values:

@GET public String getParams(@Context UriInfo ui) { MultivaluedMap<String, String> queryParams = ui.getQueryParameters(); MultivaluedMap<String, String> pathParams = ui.getPathParameters(); }

The javax.ws.rs.core.HttpHeaders interface provides information about request headers and cookies. The following code snippet shows how to obtain a map of header and cookie parameter names to values:

@GET public String getHeaders(@Context HttpHeaders hh) { MultivaluedMap<String, String> headerParams = hh.getRequestHeaders(); MultivaluedMap<String, Cookie> pathParams = hh.getCookies(); }