I want to call another web-api from my backend on a specific request of user. For example, I want to call Google FCM send message api to send a message to a specific user on an event.
Does Retrofit have any method to achieve this? If not, how I can do that?
This website has some nice examples for using spring's RestTemplate.
Here is a code example of how it can work to get a simple object:
private static void getEmployees()
{
final String uri = "http://localhost:8080/springrestexample/employees.xml";
RestTemplate restTemplate = new RestTemplate();
String result = restTemplate.getForObject(uri, String.class);
System.out.println(result);
}
Modern Spring 5+ answer using WebClient instead of RestTemplate.
Configure WebClient for a specific web-service or resource as a bean (additional properties can be configured).
#Bean
public WebClient localApiClient() {
return WebClient.create("http://localhost:8080/api/v3");
}
Inject and use the bean from your service(s).
#Service
public class UserService {
private static final Duration REQUEST_TIMEOUT = Duration.ofSeconds(3);
private final WebClient localApiClient;
#Autowired
public UserService(WebClient localApiClient) {
this.localApiClient = localApiClient;
}
public User getUser(long id) {
return localApiClient
.get()
.uri("/users/" + id)
.retrieve()
.bodyToMono(User.class)
.block(REQUEST_TIMEOUT);
}
}
Instead of String you are trying to get custom POJO object details as output by calling another API/URI, try the this solution. I hope it will be clear and helpful for how to use RestTemplate also,
In Spring Boot, first we need to create Bean for RestTemplate under the #Configuration annotated class. You can even write a separate class and annotate with #Configuration like below.
#Configuration
public class RestTemplateConfig {
#Bean
public RestTemplate restTemplate(RestTemplateBuilder builder) {
return builder.build();
}
}
Then, you have to define RestTemplate with #Autowired or #Injected under your service/Controller, whereever you are trying to use RestTemplate. Use the below code,
#Autowired
private RestTemplate restTemplate;
Now, will see the part of how to call another api from my application using above created RestTemplate. For this we can use multiple methods like execute(), getForEntity(), getForObject() and etc. Here I am placing the code with example of execute(). I have even tried other two, I faced problem of converting returned LinkedHashMap into expected POJO object. The below, execute() method solved my problem.
ResponseEntity<List<POJO>> responseEntity = restTemplate.exchange(
URL,
HttpMethod.GET,
null,
new ParameterizedTypeReference<List<POJO>>() {
});
List<POJO> pojoObjList = responseEntity.getBody();
Happy Coding :)
Create Bean for Rest Template to auto wiring the Rest Template object.
#SpringBootApplication
public class ChatAppApplication {
#Bean
public RestTemplate getRestTemplate(){
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(ChatAppApplication.class, args);
}
}
Consume the GET/POST API by using RestTemplate - exchange() method. Below is for the post api which is defined in the controller.
#RequestMapping(value = "/postdata",method = RequestMethod.POST)
public String PostData(){
return "{\n" +
" \"value\":\"4\",\n" +
" \"name\":\"David\"\n" +
"}";
}
#RequestMapping(value = "/post")
public String getPostResponse(){
HttpHeaders headers=new HttpHeaders();
headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
HttpEntity<String> entity=new HttpEntity<String>(headers);
return restTemplate.exchange("http://localhost:8080/postdata",HttpMethod.POST,entity,String.class).getBody();
}
Refer this tutorial[1]
[1] https://www.tutorialspoint.com/spring_boot/spring_boot_rest_template.htm
As has been mentioned in the various answers here, WebClient is now the recommended route.
You can start by configuring a WebClient builder:
#Bean
public WebClient.Builder getWebClientBuilder(){
return WebClient.builder();
}
Then inject the bean and you can consume an API as follows:
#Autowired
private WebClient.Builder webClientBuilder;
Product product = webClientBuilder.build()
.get()
.uri("http://localhost:8080/api/products")
.retrieve()
.bodyToMono(Product.class)
.block();
Does Retrofit have any method to achieve this? If not, how I can do that?
YES
Retrofit is type-safe REST client for Android and Java. Retrofit turns your HTTP API into a Java interface.
For more information refer the following link
https://howtodoinjava.com/retrofit2/retrofit2-beginner-tutorial
In this case need download whit my API, files hosted in other server.
In my case, don't need use a HTTP client to download the file in a external URL, I combined several answers and methods worked in previous code for files that were in my local server.
My code is:
#GetMapping(value = "/download/file/pdf/", produces = MediaType.APPLICATION_PDF_VALUE)
public ResponseEntity<Resource> downloadFilePdf() throws IOException {
String url = "http://www.orimi.com/pdf-test.pdf";
RestTemplate restTemplate = new RestTemplate();
byte[] byteContent = restTemplate.getForObject(url, String.class).getBytes(StandardCharsets.ISO_8859_1);
InputStream resourceInputStream = new ByteArrayInputStream(byteContent);
return ResponseEntity.ok()
.header("Content-disposition", "attachment; filename=" + "pdf-with-my-API_pdf-test.pdf")
.contentType(MediaType.parseMediaType("application/pdf;"))
.contentLength(byteContent.length)
.body(new InputStreamResource(resourceInputStream));
}
and it works with HTTP and HTTPS urls!
Since the question explicitly tags spring-boot, it worth noting that recent versions already ship a pre-configured instance of a builder for WebClient, thus you can directly inject it inside your service constructor without the needing to define a custom bean.
#Service
public class ClientService {
private final WebClient webClient;
public ClientService(WebClient.Builder webClientBuilder) {
webClient = webClientBuilder
.baseUrl("https://your.api.com")
}
//Add all the API call methods you need leveraging webClient instance
}
https://docs.spring.io/spring-boot/docs/2.0.x/reference/html/boot-features-webclient.html
Simplest way I have found is to:
Create an annotated interface (or have it generated from somehing like OpenAPI)
Give that interface to Spring RestTemplate Client
The Spring RestTemplate Client will parse the annotations on the interface and give you a type safe client, a proxy-instance. Any invocation on the methods will be seamlessly translated to rest-calls.
final MyApiInterface myClient = SpringRestTemplateClientBuilder
.create(MyApiInterface.class)
.setUrl(this.getMockUrl())
.setRestTemplate(restTemplate) // Optional
.setHeader("header-name", "the value") // Optional
.setHeaders(HttpHeaders) // Optional
.build();
And a rest call is made by inoking methods, like:
final ResponseEntity<MyDTO> response = myClient.getMyDto();
I created a project to test the dependency injection offered by Google Guice in my Jax-rs resources, using Resteasy.
My intentions are:
Use multiple #ApplicationPath for the versions of my API. In each class annotated with #ApplicationPath I load a set of classes for the specific version.
Each resource have a #Inject (from Google Guice) in his constructor to inject some services.
I created two classes annotated with #ApplicationPath: ApplicationV1RS and ApplicationV2RS. In both I added the same resources classes (UserResource and HelloResource), only for my test.
My Module is configured like this:
public class HelloModule implements Module
{
public void configure(final Binder binder)
{
binder.bind(IGreeterService.class).to(GreeterService.class);
binder.bind(IUserService.class).to(UserService.class);
}
}
When I call http://localhost:9095/v1/hello/world or http://localhost:9095/v2/hello/world, I receive the same error:
java.lang.RuntimeException: RESTEASY003190: Could not find constructor
for class: org.jboss.resteasy.examples.guice.hello.HelloResource
Well, as I expected, this not works. The Google Guice is not "smart" to instantiate the resource classes using the construtor for me.
But I can't find a way to work. To be really honest, I'm really confuse about how the Google Guice, Jetty and Resteasy play with each other in this scenario.
If I abandon the idea of use #ApplicationPath, my resources work with Google Guice configuring my HelloModule like this:
public class HelloModule implements Module
{
public void configure(final Binder binder)
{
binder.bind(HelloResource.class);
binder.bind(IGreeterService.class).to(GreeterService.class);
binder.bind(UserResource.class);
binder.bind(IUserService.class).to(UserService.class);
}
}
But in this case, I'm passing the control to register my resources (HelloResource and UserResource) to Guice. It's not flexible for me, I can't setup my multiple #ApplicationPath.
So, what I'm missing or not understanding?
I created a project with the problemetic code. Is very easy to setup and test: https://github.com/dherik/resteasy-guice-hello/tree/so-question/README.md
Thanks!
When you have getClasses method in your Application then it tries to create instance for all the registered resources using the default constructor which is missing in our Resources class. One way is to create a default constructor and Inject the dependencies through setter Injection.
And then instead of overriding getClasses in ApplicationV1RS and ApplicationV2RS you override getSingletons. Since Resources can be Singleton.
Below are the changes that I made to make it work the way you want.
ApplicationV1RS.java
#ApplicationPath("v1")
public class ApplicationV1RS extends Application {
private Set<Object> singletons = new HashSet<Object>();
public ApplicationV1RS(#Context ServletContext servletContext) {
}
#Override
public Set<Object> getSingletons() {
Injector injector = Guice.createInjector(new HelloModule());
HelloResource helloResource = injector.getInstance(HelloResource.class);
UserResource userResource = injector.getInstance(UserResource.class);
singletons.add(helloResource);
singletons.add(userResource);
return singletons;
}
}
ApplicationV2RS.java
#ApplicationPath("v2")
public class ApplicationV2RS extends Application {
private Set<Object> singletons = new HashSet<Object>();
public ApplicationV2RS(#Context ServletContext servletContext) {
}
#Override
public Set<Object> getSingletons() {
Injector injector = Guice.createInjector(new HelloModule());
HelloResource helloResource = injector.getInstance(HelloResource.class);
UserResource userResource = injector.getInstance(UserResource.class);
singletons.add(helloResource);
singletons.add(userResource);
return singletons;
}
}
HelloResource.java
#Path("hello")
public class HelloResource {
#Inject
private IGreeterService greeter;
public HelloResource() {
}
#GET
#Path("{name}")
public String hello(#PathParam("name") final String name) {
return greeter.greet(name);
}
}
UserResource.java
#Path("user")
public class UserResource {
#Inject
private IUserService userService;
public UserResource() {
}
#GET
#Path("{name}")
public String hello(#PathParam("name") final String name) {
return userService.getUser(name);
}
}
Add #Singleton to your Service Classes.
Hope it helps.
I have also pushed the code to forked repo. check it out
I have a WCF service which has methods that depend on reading values (OData) from the http request's querystring. I'm trying to write unit tests which inject in mock values into the querystring, then when I call the method it would use these mock values rather than erroring due to the request context not being available.
I've tried using WCFMock (which is based on Moq) however I don't see a way to set or get the querystring from the WebOperationContext that it provides.
Any ideas?
I ended up using the IOC pattern to solve this, creating an IQueryStringHelper interface that is passed into the constructor of the service. If it isn't passed in then it'll default to use the "real" QueryStringHelper class. When running test cases, it'll use an overloaded service constructor to pass in the TestQueryStringHelper instance, which lets you set a mock value for the querystring.
Here is the querystring helper code.
public interface IQueryStringHelper {
string[] GetParameters();
}
public class QueryStringHelper : IQueryStringHelper {
public string[] GetParameters() {
var properties = OperationContext.Current.IncomingMessageProperties;
var property = properties[HttpRequestMessageProperty.Name] as HttpRequestMessageProperty;
string queryString = property.QueryString;
return queryString.Split('&');
}
}
public class TestQueryStringHelper : IQueryStringHelper {
private string mockValue;
public TestQueryStringHelper(string value) {
mockValue = value;
}
public string[] GetParameters() {
return mockValue.Split('&');
}
}
And the service implementation:
public partial class RestService : IRestService {
private IAuthenticator _auth;
private IQueryStringHelper _queryStringHelper;
public RestService() : this(new Authenticator(), new QueryStringHelper()) {
}
public RestService(IAuthenticator auth, IQueryStringHelper queryStringHelper = null) {
_auth = auth;
if (queryStringHelper != null) {
_queryStringHelper = queryStringHelper;
}
}
}
And how to consume it from a test case:
string odata = String.Format("$filter=Id eq guid'{0}'", "myguid");
var service = new RestService(m_auth,new TestQueryStringHelper(odata));
var entities = service.ReadAllEntities();
Hopefully this helps someone else.
I try testing my LocalServiceUtil classes, generated by service builder, with PowerMock but always getting 'null' or '0' from Util's methods.
Test class
#RunWith(PowerMockRunner.class)
#PrepareForTest(EntityLocalServiceUtil.class)
public class EntityTest {
#Test
public void testGetAnswer() throws PortalException, SystemException {
PowerMockito.mockStatic(EntityLocalServiceUtil.class);
assertEquals("hello", EntityLocalServiceUtil.getHello());
}
}
Util class contains
public static java.lang.String getHello() {
return getService().getHello();
}
and this service working correctly on deployed portlet. What i do wrong?
You have forgot to mock the methode:
#Test
public void testGetAnswer() throws PortalException, SystemException {
PowerMockito.mockStatic(EntityLocalServiceUtil.class);
when(EntityLocalServiceUtil.getHello()).thenReturn("hello"); // <- here
assertEquals("hello", EntityLocalServiceUtil.getHello());
}
Here is my bean that is trying to inject a singleton bean InformationService :
#Path("/information/{name}")
#Stateless (name="InformationResource")
public class InformationResource {
#EJB
private InformationService appService;
#GET
#Produces(MediaType.APPLICATION_XML)
public Information getInfo(#PathParam("name") String name){
return appService.getMap().get(name);
}
#PUT
#POST
#Consumes(MediaType.APPLICATION_XML)
public Information putInfo(#PathParam("name") String name, Information info){
return appService.getMap().put(name,info);
}
#DELETE
public void deleteInfo(#PathParam("name") String name){
appService.getMap().remove(name);
}
}
This is the InformationService class
#Singleton
public class InformationService {
private Map<String,Information> map;
#PostConstruct
public void init(){
map = new HashMap<String,Information>();
map.put("daud", new Information("B.Tech","Lucknow"));
map.put("anuragh", new Information("M.Sc","Delhi"));
}
public Map<String,Information> getMap(){
return map;
}
}
Its part of a very simple JAX-RS implementation and I am deploying as war in JBoss 6.1 Final. The problem is that InformationService throwing a NullPointerException when I make the proper get request. If I initialize appService explicitly, everything works fine. Why is #EJB annotation not working ?
Are you using Jersey as REST implementation? If so, EJB injection is not supported out of the box.
This link provides more information on this and also a solution.
Check that your #Singleton is javax.ejb.Singleton.
Any other exceptions before NPE ?