I have currently trying to learn the basics of Java REST, using JAX-RS.
Within the UserService class (near bottom) of this example there is both an #GET AND #PUT method with the same #path annotation:
#GET
#Path("/users")
#Produces(MediaType.APPLICATION_XML)
public List<User> getUsers() {
return userDao.getAllUsers();
}
and
#PUT
#Path("/users")
#Produces(MediaType.APPLICATION_XML)
#Consumes(MediaType.APPLICATION_FORM_URLENCODED)
public String createUser(#FormParam("id") int id,
#FormParam("name") String name,
#FormParam("profession") String profession,
#Context HttpServletResponse servletResponse) throws IOException {
User user = new User(id, name, profession);
int result = userDao.addUser(user);
if(result == 1) {
return SUCCESS_RESULT;
}
return FAILURE_RESULT;
}
How does the Program know which method to invoke, considering that they are both point at the same #path ?
Resource classes have methods that are invoked when specific HTTP method requests are made, referred to as resource methods. In order to create Java methods that will be invoked with specific HTTP methods, a regular Java method must be implemented and annotated with one of the JAX-RS #HttpMethod annotated annotations (namely, #GET, #POST, #PUT, and #DELETE).
For more info take a look at this example1 and example2
JAX-RS evaluates the HTTP method of the request and then calls the appropriate Java method in UserService.
Related
So, in my Resource class I have the following:
#GET
#Produces(MediaType.APPLICATION_JSON)
public List<Carta> get() {
return repositorio.getAll();
}
#GET
#Path("{id}")
#Produces(MediaType.APPLICATION_JSON)
public Carta getById(#PathParam("id") int id) {
return repositorio.getID(id);
}
both works, one is a general get (will get all) and the other get by ID. I need to add a third get by String but I'm failing with the #params. I need to add this to the Resource class:
#GET
#Path("{nome}")
#Produces(MediaType.APPLICATION_JSON)
public List<Carta> getNome(#PathParam("nome") String nome) {
return repositorio.getString(nome);
}
if I comment the getById lines, my getByString works, the code is good, i just need to make both function at the same time, if it receives a number, it looks for an ID, if its a String it looks into name and description. Also, I wonder if it's better code practice to create more endpoints? Like /search/byid/xx and /search/byname/xxx instead of a general /search/xxx? Thanks.
Rather than creating a different endpoint, you should enhance List<Carta> get() to support filtering by card name.
The expected way to do that is to use the #QueryParam annotation like this:
#GET
#Produces(MediaType.APPLICATION_JSON)
public List<Carta> get(#QueryParam("name") String name) {
return repositorio.getCartas(name);
}
In the case of null name parameter, all Carta instances will be returned.
I am trying to provide endpoints that will listen on multiple versions, i.e /v1/test and /v2/test. In order not to duplicate my code, I use jersey's ability to use patterns in the #Path annotation.
Let's assume I want to provide a GET and a POST endpoint:
#Controller
#Slf4j
#Path("/")
public class TestController {
#GET
#Path("/v{version:[12]}/test")
#Produces(MediaType.APPLICATION_JSON)
public String test1(#PathParam("version") String version) {
System.out.println(String.format("GET /v%s/test called", version));
return "{\"foo\":\"bar\"}";
}
#POST
#Path("/v{version:[12]}/test")
#Produces(MediaType.APPLICATION_JSON)
public String test2(#PathParam("version") String version) {
System.out.println(String.format("POST /v%s/test called", version));
return "{\"foo\":\"bar\"}";
}
}
That works fine.
If I, however, try to use a specific path for the GET endpoints and use a pattern for the POST endpoint, I run into trouble.
Here the controller that would not work:
#Controller
#Slf4j
#Path("/")
public class TestController {
#GET
#Path("/v1/test")
#Produces(MediaType.APPLICATION_JSON)
public String test1() {
System.out.println("GET /v1/test called");
return "{\"foo\":\"bar1\"}";
}
#GET
#Path("/v2/test")
#Produces(MediaType.APPLICATION_JSON)
public String test2() {
System.out.println("GET /v2/test called");
return "{\"foo\":\"bar2\"}";
}
#POST
#Path("/v{version:[12]}/test")
#Produces(MediaType.APPLICATION_JSON)
public String test3(#PathParam("version") String version) {
System.out.println(String.format("POST /v%s/test called", version));
return "{\"foo\":\"barPOST\"}";
}
}
Doing GET /v1/test or GET /v2/test works fine, POST /v1/test however does not.
I get a 405 Method Not Allowed Exception.
As far as I got it the exception is thrown in the MethodSelectingRouter when it recognizes the path, but cannot find a method with the appropriate HTTP verb.
The issue seems to be that it picks the most specific path (/v1/test in my case) for which it does not know the POST verb.
Does anybody have an idea how to avoid this problem?
Cheers
PS: I am using spring boot with jersey (i.e. spring-boot-starter-web and spring-boot-starter-jersey) in version 1.5.2.RELEASE
Consider this case:-
I am injecting HttpServletRequest in a Rest Service like
#Context
HttpServletRequest request;
And use it in a method like:-
#GET
#Path("/simple")
public Response handleSimple() {
System.out.println(request.getParameter("myname"));
return Response.status(200).entity("hello.....").build();
}
This works fine but when I try to send it through POST method and replace the #GET by #POST annotation, I get the parameter value null.
Please suggest me where I am mistaking.
You do not need to get your parameters etc out of the request. The JAX-RS impl. handles that for you.
You have to use the parameter annotations to map your parameters to method parameters. Casting converting etc. is done automaticly.
Here your method using three differnt ways to map your parameter:
// As Pathparameter
#POST
#Path("/simple/{myname}")
public Response handleSimple(#PathParam("myname") String myName) {
System.out.println(myName);
return Response.status(200).entity("hello.....").build();
}
// As query parameter
#POST
#Path("/simple")
public Response handleSimple(#QueryParam("myname") String myName) {
System.out.println(myName);
return Response.status(200).entity("hello.....").build();
}
// As form parameter
#POST
#Path("/simple")
public Response handleSimple(#FormParam("myname") String myName) {
System.out.println(myName);
return Response.status(200).entity("hello.....").build();
}
Documentation about JAX-RS Annotations from Jersey you can find here:
https://jersey.java.net/documentation/latest/jaxrs-resources.html
In my app users can register, that users can post workouts and comments on workouts.
I design following resources and URIs:
USERS
/users
/users/{id}
WORKOUTS
/workouts
/workouts/{id}
COMMENTS
/workouts{id}/comments
/workouts{id}/comments/{id}
Since /workouts URI returns timeline, I tried to map user's workouts like /workouts?user=userId
I don´t know how distinguish between get all collection and get collection filtered by #QueryParam, because:
#GET
#Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
public Practicas getPracticas() {
List<Practica> listaPracticas = practicaDao.getPracticas();
Practicas practicas = new Practicas();
practicas.setPracticas(listaPracticas);
return practicas;
}
#GET
#Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
public Practicas getPracticasUsuario(#QueryParam("idUsuario") int idUsuario) {
List<Practica> listaPracticas = practicaDao.getPracticasByUser(idUsuario);
Practicas practicas = new Practicas();
practicas.setPracticas(listaPracticas);
return practicas;
}
throw following exception:
org.glassfish.jersey.server.model.ModelValidationException: Validation of the application resource model has failed during application initialization.
[[FATAL] A resource model has ambiguous (sub-)resource method for HTTP method GET and input mime-types as defined by #Consumes and #Produces annotations at Java methods public com.sporty.model.Practicas com.sporty.resource.PracticasResource.getPracticas() and public com.sporty.model.Practicas com.sporty.resource.PracticasResource.getPracticasUsuario(int) at matching regular expression /practicas. These two methods produces and consumes exactly the same mime-types and therefore their invocation as a resource methods will always fail.; source='org.glassfish.jersey.server.model.RuntimeResource#1cc465f']
Is solution add another level on URI like /workouts/search?user=userId?
Is a problem derived from a poor URI design?
Thanks in advance
I think you're looking for something like:
#GET
#Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
public Practicas getPracticasUsuario(#QueryParam("idUsuario") Integer idUsuario) {
final List<Practica> listaPracticas;
if (idUsario != null) {
practicaDao.getPracticasByUser(idUsuario);
} else {
practicaDao.getPracticas();
}
Practicas practicas = new Practicas();
practicas.setPracticas(listaPracticas);
return practicas;
}
I have two REST classes for a simple web service (Jersey and GlassFish) that involves user resources - one to operate on all users (e.g., a factory for #POSTing) and another on individual users (e.g., #GET, #PUT, #DELETE). They are at:
#Stateless #Path("users") public class AllUsersResource {...}
#Stateless #Path("user") public class OneUserResource {...}
respectively. When POSTing to AllUsersResource I want to return the Location (via Response.created(uri).build()) of the new User, e.g.,
http://localhost:8080/.../user/152
My question is how to do this. AllUsersResource injects #Context UriInfo uriInfo, but that does not get me #Path info for OneUserResource, only that of the current call ("users"). The way I finally got it working was simply to use reflection, but I'm worried it is brittle and unclean:
OneUserResource.class.getAnnotation(Path.class).value();
Searching StackOverflow the only other things I found to try were the following, without success:
com.sun.jersey.api.core.ResourceContext
javax.ws.rs.core.UriInfo.getMatchedResources()
#javax.inject.Inject OneUserResource oneUserRes;
Any help would be terrific!
You can use UriBuilder.fromresource(), but this only works if the supplied Resource class is a root resource (this is clearly mentioned in the javadocs). I found a way to achieve this even if you are in a sub-resource class:
#POST
#Consumes({MediaType.APPLICATION-XML, MediaType.APPLICATION-JSON})
public Response createUser(final User user, #Context UriInfo uriInfo) {
// persist the user here
URI uri = uriInfo.getAbsolutePathBuilder().path(user.getId()).build();
return Response.created(uri).build();
}
I found a couple of javax.ws.rs.core.UriBuilder methods that did the trick, which I wanted to share in case others had this question. They are: UriBuilder.fromResource(OneUserResource.class) and javax.ws.rs.core.UriBuilder.path(Class). I used the latter in a one-shot call:
URI newUserUri = uriInfo.getBaseUriBuilder().path(OneUserResource.class).path("/" + user.getId()).build();
return Response.created(newUserUri).build();
With the strict REST concept you can make it as one root resource
#POST /users -> CREATE a single user
#GET /users -> READ all users
#PUT /users -> UPDATE (REPLACE) all users ##?
#DELETE /users -> DELETE all users ##?
#POST /users/{id} -> CREATE a single user's some other child; ##?
#GET /users/{id} -> READ a single user
#PUT /users/{id} -> UPDATE a single user
#DELETE /users/{id} -> DELETE a single user
#Path("/users")
#Stateless
public class UsersResouce {
// /users
#POST
#Consumes({MediaType.APPLICATION-XML, MediaType.APPLICATION-JSON})
public Response createUser(final User user) {
// persist the user here
return Response.created("/" + user.getId()).build();
}
// /users
#GET
#Produces({MediaType.APPLICATION-XML, MediaType.APPLICATION-JSON})
public Response readUsers() {
//return all users
}
// /users/{id}
#GET
#Path("/{user_id: \\d+}")
#Produces({MediaType.APPLICATION-XML, MediaType.APPLICATION-JSON})
public Response readUser(
#PathParam("user_id") final Long userId) {
final User persisted = userBean.find(userId);
if (persisted == null) {
return Response.status(Status.NOT_FOUND).build();
}
return Response.ok().entity(persisted).build();
}
// /users/{id}
#Consumes({MediaType.APPLICATION-XML, MediaType.APPLICATION-JSON})
#PUT
#Path("/{user_id: \\d+}")
public Response updateUser(
#PathParam("user_id") final Long userId,
final User mergeable) {
final User persisted = userBean.find(userId);
if (persisted == null) {
userBean.persist(mergeable);
} else {
persist.setName(mergeable.getName());
userBean.merge(persisted);
}
return Response.status(Status.NO_CONTENT).build();
}
// /users/{id}
#DELETE
#Path("/{user_id: \\d+}")
public Response deleteUser(
#PathParam("user_id") final Long userId) {
userBean.delete(userId);
return Response.status(Status.NO_CONTENT).build();
}
#EJB
private UserBean userBean;
}
As of JAX-RS 2.0, the most correct way (As far as I know) is to use the builder method like so:
String uri = uriInfo.getBaseUriBuilder()
.path(ODataV4Endpoint.class)
.path(ODataV4Endpoint.class, "serviceEndpointJSONCatalog")
.resolveTemplate("endpointId", endpointId).build().toString();
FYI, I need to call path twice in my case, once for the path annotation on the class, and the second time for the annotation on the method. I suspected the call to the method would do both, but it does not.
The Path annotation on the endpoint serviceEndpointJSONCatalog declared a parameter, like so: 'endpoint/{endpointId}', so the call to resolveTemplate was needed. Otherwise you would just call path(Class cl, String method).
In my case I created a builder and a symbolic way to reference the methods so the compiler / runtime could check them.