i have implemented rest webservices using Jersey, and whenever some exception occur on the server side, the client gets a generic HTTP 500 Internal Server Error, with no more info of the real exception. I found that people usually catch any exception on the server side, then throws a WebApplicationException, but even this way the client keeps getting the generic HTTP 500 Internal Server Error.
This is my webservice:
#PUT
#Produces(MediaType.APPLICATION_XML)
#Consumes(MediaType.APPLICATION_XML)
#Path("/transmitir")
public WrapperTransmissaoRetorno receber(WrapperTransmissao wrapperRecepcao) {
WrapperTransmissaoRetorno retorno = new WrapperTransmissaoRetorno();
retorno.setCodigoMaster(new Random().nextInt());
retorno.setDataRetorno(new Date());
if(true){
throw new WebApplicationException("Este pau eh bem graudo");
}
return retorno;
}
This is the code that calls the client:
try {
WsTransmissaoCliente client = new WsTransmissaoCliente();
WrapperTransmissao wrapperRecepcao = new WrapperTransmissao();
Transferencia transferencia = new Transferencia();
transferencia.setCodigoTabela(23);
transferencia.setCodigoTransferencia(56);
transferencia.setDataRetorno(new Date());
transferencia.setDataTransmissao(new Date(System.currentTimeMillis()+3000000));
transferencia.setNomeTabela("CUPOM");
transferencia.setTipoOperacao(TipoOperacao.UPDATE);
wrapperRecepcao.setTransferencia(transferencia);
Jumento jumento = new Jumento();
jumento.setIdade(24);
jumento.setNome("José");
wrapperRecepcao.setObjeto(jumento);
// Cabrito cabrito = new Cabrito();
// cabrito.setAltura(56);
// cabrito.setPeso(120.0);
// wrapperRecepcao.setObjeto(cabrito);
WrapperTransmissaoRetorno retorno = client.transmitir(wrapperRecepcao);
System.out.println("Retorno do WS: "+retorno);
} catch (Exception e) {
WebApplicationException exx = (WebApplicationException) e;
exx.printStackTrace();
}
How to avoid this and get the real exception? Or at least the message?
UPDATE
Here is the object i am sending as a response:
package br.atualy.integracaocheckout.wrappers;
import java.util.Date;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement
public class WrapperTransmissaoRetorno {
private Date dataRetorno;
private Integer codigoMaster;
public Date getDataRetorno() {
return dataRetorno;
}
public void setDataRetorno(Date dataRetorno) {
this.dataRetorno = dataRetorno;
}
public Integer getCodigoMaster() {
return codigoMaster;
}
public void setCodigoMaster(Integer codigoMaster) {
this.codigoMaster = codigoMaster;
}
#Override
public String toString() {
return "WrapperRecepcaoRetorno{" + "dataRetorno=" + dataRetorno + ", codigoMaster=" + codigoMaster + '}';
}
}
UPDATE 2
And here is the client:
import br.atualy.integracaocheckout.wrappers.WrapperTransmissao;
import br.atualy.integracaocheckout.wrappers.WrapperTransmissaoRetorno;
import javax.ws.rs.ClientErrorException;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.WebTarget;
public class WsTransmissaoCliente {
private final WebTarget webTarget;
private final Client client;
private static final String BASE_URI = "http://localhost:8080/IntegracaoCheckout/webresources";
public WsTransmissaoCliente() {
client = javax.ws.rs.client.ClientBuilder.newClient();
webTarget = client.target(BASE_URI).path("transmissao");
}
// public String receber() throws ClientErrorException {
// WebTarget resource = webTarget;
// resource = resource.path("receber");
// return resource.request(javax.ws.rs.core.MediaType.APPLICATION_XML).get(String.class);
// }
public WrapperTransmissaoRetorno transmitir(WrapperTransmissao requestEntity) throws ClientErrorException {
return webTarget.path("transmitir")
.request(javax.ws.rs.core.MediaType.APPLICATION_XML)
.put(javax.ws.rs.client.Entity.entity(requestEntity, javax.ws.rs.core.MediaType.APPLICATION_XML), WrapperTransmissaoRetorno.class);
}
public void close() {
client.close();
}
}
If using jawax.ws.rs.core.Response object.
SERVER :: In case of exception/failure set it as :
// do stuff
// here e.getMessage() can be custom failure message too
response = Response.serverError().entity(e.getMessage()).build();
// return response object
return response;
CLIENT :: On the client side check following :
if(response != null && reponse.getStatus() == Response.Status.INTERNAL_SERVER_ERROR.getStatusCode()) {
String serverErrorMsg = response.readEntity(String.class);
throw new Exception(serverErrorMsg);
}
Generally it's better to declare your method as returning a Response object instead of a user-defined type, and set the data as the entity. Then if you want to indicate that an exception has happened, you can just pass that exception as the entity of the Response you are returning.
e.g.
#GET
#Path("/foo")
public Response getFoo() {
try {
// do stuff
return Response.ok(someData).build();
} catch (Exception e) {
return Response.serverError().entity(e).build();
}
}
You'll notice that this way you don't ever end up actually throwing an exception out of your method, but rather return an explicit 500 response with an exception as the entity. This way you can still throw exceptions out of your code, but they'll be handled nicely.
EDIT
I'm not sure what your client wrapper code is doing, but you can pass the expected response data type into your call with the normal REST client:
Client client = ClientBuilder.newClient();
WebTarget target = client.target("http://foo.com/foo");
String response = target.request().get(String.class);
or you can also pull it out of the Response using the readEntity() method:
Client client = ClientBuilder.newClient();
WebTarget target = client.target("http://foo.com/foo");
Response response = target.request().get();
String entity = response.readEntity(String.class);
It sounds like what you need to do is check the return code, and then parse the entity as a either a WrapperTransmissaoRetorno or a WebApplicationException depending on what code was returned:
Response response = client.transmitir(wrapperRecepcao);
if (response.getStatus() == Response.Status.OK.getStatusCode()) { // 200
WrapperTransmissaoRetorno retorno = response.readEntity(WrapperTransmissaoRetorno.class);
// do stuff
} else if (response.getStatus() == Response.Status.INTERNAL_SERVER_ERROR.getStatusCode()) { // 500
WebApplicationException e = response.readEntity(WebApplicationException.class);
// do stuff
} // etc for other response codes
Use response object in webapplication excemption. It should work.
From java docs:
WebApplicationException(String message)
Construct a new instance with a blank message and default HTTP status code of 500.
Its a blank message. I haven't tried it myself. I guess this is the problem.
https://jersey.java.net/apidocs/2.6/jersey/javax/ws/rs/WebApplicationException.html
Even after all the suggestions i could not manage to throw the exception to the client.
So what i did was to put a String property inside my returning class, so when an exception occurs on the server side, this String will contain the exception message and i can get it on the client.
Related
I am currently working with the Restlets framework, and I cannot find a way to manually set the HTTP response code within a service method. Consider the following snippet of code:
public class MyResource extends ServerResource {
#Post("json")
public Representation doSomething(Representation entity) throws IOException {
int status = 200;
try {
// do something which might throw an exception
}
catch (Exception e) {
// log the exception
// *** I would like to assign HTTP status 500 here ***
status = 500;
}
JSONObject responseJSON = new JSONObject();
responseJSON.put("result", "some data");
Representation rep = new JsonRepresentation(responseJSON.toJSONString());
return rep;
}
}
I have the ability to catch and log an exception, should one occur, but it is not clear how I can change the HTTP response code. As far as I know, returning from doSomething will automatically be handled by Restlets with an 200 HTTP response code.
I know how to assign the status code directly from a filter or servlet, but is it possible to do this within Restlets, without going down the servlet layer?
As far as I know, there is an object called ResponseEntity which you can use to operate with microservices and a request-response programming model, which allows you to specify the returning HTTP return code. However, you need entities for this, and I think this goes below your abstraction level of Servlets.
You can change them to some predefined values such as HTTP.INTERNAL_SERVER_ERROR and such, which translate to a value in the end, which you can Google in the end.
I hope this was of some help
EDIT:
Import the necessary resource for a ResponseEntity object. In STS, it is
import org.springframework.http.ReponseEntity;
import org.springframework.http.HttpStatus;
public class MyResource extends ServerResource {
#Post("json")
public ResponseEntity<Representation> doSomething(Representation entity) throws IOException {
int status = 200;
try {
// do something which might throw an exception
}
catch (Exception e) {
ResponseEntity<Representation> response = null;
response = new ResponseEntity<Representation>(HttpStatus.INTERNAL_SERVER_ERROR);
return response;
}
JSONObject responseJSON = new JSONObject();
responseJSON.put("result", "some data");
Representation rep = new JsonRepresentation(responseJSON.toJSONString());
return rep;
}
And sorry for the delay. I am new to Stack Overflow
Hey so I'm trying to send some json-object to a rest web service, then get the value of some specific keys, then process the data to finally return a new json-object which is going to be used in another place. Anyway, I'm getting HTTP 204 when I try to communicate with the service.
My rest service looks like this
#Path("/example")
public class PdfMaker {
#POST
#Path("/post")
#Consumes(MediaType.APPLICATION_JSON)
#Produces(MediaType.APPLICATION_JSON)
public Response PruebasMet(JSONObject json) throws IOException, JSONException{
try{
String xml = json.getString("xml");
String plantilla = json.getString("plant");
//method that uses "xml" and "plant" and returns "pdf"
JSONObject response = new JSONObject();
response.put("pdf", pdf);
return Response.status(200).entity(pdfb64.toString()).build();
}catch(Exception e){
e.getStackTrace();
return null;
}
}
and I'm trying to communicate with this
public class Jersey {
public static String baseuri = "http://localhost:8080/PdfMakerGF/rest/example/post";
public static void main(String[] args) {
try {
ClientConfig config = new DefaultClientConfig();
Client client = Client.create(config);
WebResource webResource = client.resource(baseuri);
JSONObject objTest = new JSONobject();
objTest.put("xml","Data1");
objTest.put("plan", "Data2");
ClientResponse res = webResource.header("Content-Type","application/json;charset=UTF-8")
.post(ClientResponse.class, objTest.toString());
System.out.println("output..." + "\n");
System.out.println("Answer "+res);
} catch (Exception e) {
e.printStackTrace();
}
}
But the response that I receive is this one
Answer POST http://localhost:8080/PdfMakerGF/rest/example/post
returned a response status of 204 No Content
Obviously there is something wrong but can't see what is it.
Since I'm stuck with this. Any kind of help would be appreciated.
I'm using netbeans 8.1, Glassfish 4.1 and Jersey.
Thanks
If your server runs into an exception and goes to the catch block, it returns null which corresponds to HTTP 204 (No Content). As sisyphus commented, there should be some exception in the server standard output.
So you probably need to:
Return a different response code (e.g. INTERNAL_SERVER_ERROR or
BAD_REQUEST) in the catch block
Check why the server code is throwing
the exception
Most likely you get an Exception. I guess it is because you have "plant" in one place and "plan" in another.
okey so finaly it works what i need to change was the way that the service was reciving the data, with a inner class in my case, end up working like this ..
Class Aux{
String xml;
String plant;
//generate gettes and setters :)
}
#Path("/example")
public class PdfMaker {
#POST
#Path("/post")
#Consumes(MediaType.APPLICATION_JSON)
#Produces(MediaType.APPLICATION_JSON)
public Response PruebasMet(Aux json) throws IOException,
JSONException{
try{
String xml = json.getXml();
String plant = json.getPlant();
//method that uses "xml" and "plant" and returns "pdf"
JSONObject response = new JSONObject();
response.put("pdf", pdf);
return Response.status(200).entity(pdf)).build();
}catch(Exception e){
e.getStackTrace();
return null;
}
}
and the client is ..
Client client = new Client();
WebResource wresource = client.resource("http://localhost:8080/PdfMakerGF/rest/example/post");
JSONObject json = new JSONObject();
json.put("xml", DATA);
json.put("plant", DATA);
ClientResponse response =
wresource.type("application/json").post(ClientResponse.class,
json.toString());
out = response.getEntity(String.class);
System.out.println("RES = "+response);
System.out.println("OUT = "+out);
out has the info that the service is Providing
I have application with many rest services, most of them follows this pattern:
class RestService{
public Response execute1() {
try{
// doLogicThere...
return response;
} catch () {
// handle exception and build Response object..
return response;
}
}
public Response execute2() {
try{
// doLogicThere...
return response;
} catch() {
// handle exception and build Response object..
return response;
}
}
}
catch clause is the same for all methods so I want to have pattern like this below but with try/catch called from somewhere else. I want to do kind of wrapping these methods.
class RestService{
public Response execute1() {
// doLogicThere...
return response;
}
public Response execute2() {
// doLogicThere...
return response;
}
}
JAX-WS includes a mechanism for creating the proper response for each type of exception that your REST methods might produce.
For each exception type, create a class that implements ExceptionMapper<E> where E is the type of exception. You create your response in the toResponse method. You need to annotate your exception mapper with #Provider, in order to register it with the JAX-RS runtime.
#Provider
public class UserNotFoundMapper implements ExceptionMapper<UserNotFoundException> {
#Override
public Response toResponse(UserNotFoundException e) {
return Response.status(404).entity(e.getMessage()).type("text/plain").build();
}
}
You can create an interface with the method you need to execute. Then you can wrap that method in a try catch in a new method. This will avoid the use of many repeated try catch blocks.
You can do something like that:
public interface CallableClass {
public Response call();
}
...
class RestService {
private Response handleCall(CallableClass myClass) {
try {
return myClass.call();
} catch (Exception e) {
// Handle exception and return a particular response
...
}
}
public Response execute1() {
return handleCall(/* put anonymous class of type CallableClass here */);
}
public Response execute2() {
return handleCall(/* put anonymous class of type CallableClass here */);
}
}
If you are using java 8 you can replace the anonynous class with a more elegant lambda expression.
Here a simple example with lambdas
public Response executeLambda() {
return handleCall(() -> {
... // Your code here
return response;
});
}
You can use the "throws" keyword to indicate that a method throws certain exceptions. Then when you call that method you can simply wrap the call in a try/catch block.
See: https://docs.oracle.com/javase/tutorial/essential/exceptions/declaring.html
If you are building RESTFul Service using SPring MVC, you do have a better option of leveraging using following annotation "#ExceptionHandler(CustomExceptionForRestServices.class)". Where you can write your customException or have a comma seperated List of exception classes you expect your method to throw.
The #ExceptionHandler value can be set to an array of Exception types. If an exception is thrown matches one of the types in the list, then the method annotated with the matching #ExceptionHandler will be invoked. If the annotation value is not set then the exception types listed as method arguments are used.
Much like standard controller methods annotated with a #RequestMapping annotation, the method arguments and return values of #ExceptionHandler methods are very flexible.
I have created a little example in plain AspectJ, i.e. without any Spring. I even created a dummy Response class just so as to show the basic mechanics behind aspect-driven exception handling:
Dummy response class:
package de.scrum_master.app;
public class Response {
private int statusCode;
private String message;
public Response(int statusCode) {
this.statusCode = statusCode;
switch (statusCode) {
case 200:
message = "OK";
break;
case 202:
message = "Accepted";
break;
case 401:
message = "Unauthorized";
break;
default:
message = "Unknown status";
}
}
public int getStatusCode() {
return statusCode;
}
#Override
public String toString() {
return "Response(statusCode=" + statusCode + ", message=" + message + ")";
}
}
Driver application with two methods to be intercepted:
As you can see, both methods randomly throw exceptions which ought to be caught by an aspect later.
package de.scrum_master.app;
import java.util.Random;
public class RestService {
private static final Random RANDOM = new Random();
public Response someRequest() {
Response response = new Response(RANDOM.nextBoolean() ? 200 : 401);
if (response.getStatusCode() != 200)
throw new RuntimeException("request failed: " + response);
return response;
}
public Response anotherRequest(String argument) {
Response response = new Response(RANDOM.nextBoolean() ? 200 : 401);
if (response.getStatusCode() != 200)
throw new RuntimeException("request failed: " + response);
return response;
}
public static void main(String[] args) {
RestService restService = new RestService();
for (int i = 0; i < 3; i++) {
System.out.println(restService.someRequest());
System.out.println(restService.anotherRequest("foo"));
}
}
}
Exception handling aspect:
package de.scrum_master.aspect;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import de.scrum_master.app.Response;
#Aspect
public class ResponseErrorHandler {
#Around("execution(de.scrum_master.app.Response *(..))")
public Response handleError(ProceedingJoinPoint thisJoinPoint) {
System.out.println("\n" + thisJoinPoint);
try {
return (Response) thisJoinPoint.proceed();
}
catch (Exception e) {
System.out.println(" Handling exception: " + e.getMessage());
return new Response(202);
}
}
}
Console log:
execution(Response de.scrum_master.app.RestService.someRequest())
Response(statusCode=200, message=OK)
execution(Response de.scrum_master.app.RestService.anotherRequest(String))
Response(statusCode=200, message=OK)
execution(Response de.scrum_master.app.RestService.someRequest())
Response(statusCode=200, message=OK)
execution(Response de.scrum_master.app.RestService.anotherRequest(String))
Handling exception: request failed: Response(statusCode=401, message=Unauthorized)
Response(statusCode=202, message=Accepted)
execution(Response de.scrum_master.app.RestService.someRequest())
Response(statusCode=200, message=OK)
execution(Response de.scrum_master.app.RestService.anotherRequest(String))
Handling exception: request failed: Response(statusCode=401, message=Unauthorized)
Response(statusCode=202, message=Accepted)
Feel free to ask follow-up questions if you do not understand the answer.
In my Jax-Rs(Jersey + Jetty) application, I've added some custom headers to the response so that I can use those at the client side. I'm using ResponseBuilder to achieve this.
#Provider
public class CustomExceptionMapper implements ExceptionMapper<CustomException> {
private static final Logger LOGGER = LoggerFactory.getLogger(CustomExceptionMapper.class);
#Context
private HttpHeaders headers;
#Override
public Response toResponse(CustomException exception) {
String errorKey = null;
String errorArgs[] = null;
// log stack trace
LOGGER.error("An error occurred during the operation.", exception);
if (exception instanceof MetadataServerException) {
errorKey = ExceptionMapperUtil.checkForDBException(exception.getCause());
if (errorKey != null) {
return Response.status(Response.Status.INTERNAL_SERVER_ERROR)
.entity(MessageSourceUtils.getMessage(errorKey, errorArgs, ExceptionMapperUtil.getLocale(headers))).type(MediaType.TEXT_PLAIN).build();
}
}
if(ErrorCodes.INTERNAL_SERVER_ERROR.equals(exception.getMessageKey()) &&
(exception.getMessageArguments() == null || exception.getMessageArguments().length==0) ){
exception.setMessageArguments(new Object[]{"while executing the operation"});
}
// prepare response to be sent to client
return Response.status(ResponseCodeMapper.mapToStatusCode(exception)).
entity(exception.getMessage(ExceptionMapperUtil.getLocale(headers))).
type(MediaType.TEXT_PLAIN).header("errorCode", exception.getMessageKey()).
build();
}
}
And also, I've confirmed that that the response object is getting built properly. However, for some reason, the returned response doesn't contain my custom header. Any clues as to to what is going wrong ?
I am starting to use the new client API library in JAX-RS and really loving it so far. I have found one thing I cannot figure out however. The API I am using has a custom error message format that looks like this for example:
{
"code": 400,
"message": "This is a message which describes why there was a code 400."
}
It returns 400 as the status code but also includes a descriptive error message to tell you what you did wrong.
However the JAX-RS 2.0 client is re-mapping the 400 status into something generic and I lose the good error message. It correctly maps it to a BadRequestException, but with a generic "HTTP 400 Bad Request" message.
javax.ws.rs.BadRequestException: HTTP 400 Bad Request
at org.glassfish.jersey.client.JerseyInvocation.convertToException(JerseyInvocation.java:908)
at org.glassfish.jersey.client.JerseyInvocation.translate(JerseyInvocation.java:770)
at org.glassfish.jersey.client.JerseyInvocation.access$500(JerseyInvocation.java:90)
at org.glassfish.jersey.client.JerseyInvocation$2.call(JerseyInvocation.java:671)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:228)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:424)
at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:667)
at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:396)
at org.glassfish.jersey.client.JerseyInvocation$Builder.get(JerseyInvocation.java:296)
Is there some sort of interceptor or custom error handler that can be injected so that I get access to the real error message. I've been looking through documentation but can't see any way of doing it.
I am using Jersey right now, but I tried this using CXF and got the same result. Here is what the code looks like.
Client client = ClientBuilder.newClient().register(JacksonFeature.class).register(GzipInterceptor.class);
WebTarget target = client.target("https://somesite.com").path("/api/test");
Invocation.Builder builder = target.request()
.header("some_header", value)
.accept(MediaType.APPLICATION_JSON_TYPE)
.acceptEncoding("gzip");
MyEntity entity = builder.get(MyEntity.class);
UPDATE:
I implemented the solution listed in the comment below. It is slightly different since the classes have changed a bit in the JAX-RS 2.0 client API. I still think it is wrong that the default behavior is to give a generic error message and discard the real one. I understand why it wouldn't parse my error object, but the un-parsed version should have been returned. I end up having the replicate exception mapping that the library already does.
Thanks for the help.
Here is my filter class:
#Provider
public class ErrorResponseFilter implements ClientResponseFilter {
private static ObjectMapper _MAPPER = new ObjectMapper();
#Override
public void filter(ClientRequestContext requestContext, ClientResponseContext responseContext) throws IOException {
// for non-200 response, deal with the custom error messages
if (responseContext.getStatus() != Response.Status.OK.getStatusCode()) {
if (responseContext.hasEntity()) {
// get the "real" error message
ErrorResponse error = _MAPPER.readValue(responseContext.getEntityStream(), ErrorResponse.class);
String message = error.getMessage();
Response.Status status = Response.Status.fromStatusCode(responseContext.getStatus());
WebApplicationException webAppException;
switch (status) {
case BAD_REQUEST:
webAppException = new BadRequestException(message);
break;
case UNAUTHORIZED:
webAppException = new NotAuthorizedException(message);
break;
case FORBIDDEN:
webAppException = new ForbiddenException(message);
break;
case NOT_FOUND:
webAppException = new NotFoundException(message);
break;
case METHOD_NOT_ALLOWED:
webAppException = new NotAllowedException(message);
break;
case NOT_ACCEPTABLE:
webAppException = new NotAcceptableException(message);
break;
case UNSUPPORTED_MEDIA_TYPE:
webAppException = new NotSupportedException(message);
break;
case INTERNAL_SERVER_ERROR:
webAppException = new InternalServerErrorException(message);
break;
case SERVICE_UNAVAILABLE:
webAppException = new ServiceUnavailableException(message);
break;
default:
webAppException = new WebApplicationException(message);
}
throw webAppException;
}
}
}
}
I believe you want to do something like this:
Response response = builder.get( Response.class );
if ( response.getStatusCode() != Response.Status.OK.getStatusCode() ) {
System.out.println( response.getStatusType() );
return null;
}
return response.readEntity( MyEntity.class );
Another thing you can try (since I don't know where this API puts stuff -- i.e. in the header or entity or what) is:
Response response = builder.get( Response.class );
if ( response.getStatusCode() != Response.Status.OK.getStatusCode() ) {
// if they put the custom error stuff in the entity
System.out.println( response.readEntity( String.class ) );
return null;
}
return response.readEntity( MyEntity.class );
If you would like to generally map REST response codes to Java exception you can add a client filter to do that:
class ClientResponseLoggingFilter implements ClientResponseFilter {
#Override
public void filter(final ClientRequestContext reqCtx,
final ClientResponseContext resCtx) throws IOException {
if ( resCtx.getStatus() == Response.Status.BAD_REQUEST.getStatusCode() ) {
throw new MyClientException( resCtx.getStatusInfo() );
}
...
In the above filter you can create specific exceptions for each code or create one generic exception type that wraps the Response code and entity.
There are other ways to getting a custom error message to the Jersey client besides writing a custom filter. (although the filter is an excellent solution)
1) Pass error message in an HTTP header field.
The detail error message could be in the JSON response and in an additional header field, such as "x-error-message".
The Server adds the HTTP error header.
ResponseBuilder rb = Response.status(respCode.getCode()).entity(resp);
if (!StringUtils.isEmpty(errMsg)){
rb.header("x-error-message", errMsg);
}
return rb.build();
The Client catches the exception, NotFoundException in my case, and reads the response header.
try {
Integer accountId = 2222;
Client client = ClientBuilder.newClient();
WebTarget webTarget = client.target("http://localhost:8080/rest-jersey/rest");
webTarget = webTarget.path("/accounts/"+ accountId);
Invocation.Builder ib = webTarget.request(MediaType.APPLICATION_JSON);
Account resp = ib.get(new GenericType<Account>() {
});
} catch (NotFoundException e) {
String errorMsg = e.getResponse().getHeaderString("x-error-message");
// do whatever ...
return;
}
2) Another solution is to catch the exception and read the response content.
try {
// same as above ...
} catch (NotFoundException e) {
String respString = e.getResponse().readEntity(String.class);
// you can convert to JSON or search for error message in String ...
return;
}
The class WebApplicationException was designed for that but for some reason it ignores and overwrites what you specify as parameter for the message.
For that reason I created my own extension WebAppException that honors the parameters. It is a single class and it doesn't require any response filter or a mapper.
I prefer exceptions than creating a Response as it can be thrown from anywhere while processing.
Simple usage:
throw new WebAppException(Status.BAD_REQUEST, "Field 'name' is missing.");
The class:
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.core.Response.Status.Family;
import javax.ws.rs.core.Response.StatusType;
public class WebAppException extends WebApplicationException {
private static final long serialVersionUID = -9079411854450419091L;
public static class MyStatus implements StatusType {
final int statusCode;
final String reasonPhrase;
public MyStatus(int statusCode, String reasonPhrase) {
this.statusCode = statusCode;
this.reasonPhrase = reasonPhrase;
}
#Override
public int getStatusCode() {
return statusCode;
}
#Override
public Family getFamily() {
return Family.familyOf(statusCode);
}
#Override
public String getReasonPhrase() {
return reasonPhrase;
}
}
public WebAppException() {
}
public WebAppException(int status) {
super(status);
}
public WebAppException(Response response) {
super(response);
}
public WebAppException(Status status) {
super(status);
}
public WebAppException(String message, Response response) {
super(message, response);
}
public WebAppException(int status, String message) {
super(message, Response.status(new MyStatus(status, message)). build());
}
public WebAppException(Status status, String message) {
this(status.getStatusCode(), message);
}
public WebAppException(String message) {
this(500, message);
}
}
A much more concise solution for anyone stumbling on this:
Calling .get(Class<T> responseType) or any of the other methods that take the result type as an argument Invocation.Builder will return a value of the desired type instead of a Response. As a side effect, these methods will check if the received status code is in the 2xx range and throw an appropriate WebApplicationException otherwise.
From the documentation:
Throws: WebApplicationException in case the response status code of
the response returned by the server is not successful and the
specified response type is not Response.
This allows to catch the WebApplicationException, retrieve the actual Response, process the contained entity as exception details (ApiExceptionInfo) and throw an appropriate exception (ApiException).
public <Result> Result get(String path, Class<Result> resultType) {
return perform("GET", path, null, resultType);
}
public <Result> Result post(String path, Object content, Class<Result> resultType) {
return perform("POST", path, content, resultType);
}
private <Result> Result perform(String method, String path, Object content, Class<Result> resultType) {
try {
Entity<Object> entity = null == content ? null : Entity.entity(content, MediaType.APPLICATION_JSON);
return client.target(uri).path(path).request(MediaType.APPLICATION_JSON).method(method, entity, resultType);
} catch (WebApplicationException webApplicationException) {
Response response = webApplicationException.getResponse();
if (response.getMediaType().equals(MediaType.APPLICATION_JSON_TYPE)) {
throw new ApiException(response.readEntity(ApiExceptionInfo.class), webApplicationException);
} else {
throw webApplicationException;
}
}
}
ApiExceptionInfo is custom data type in my application:
import lombok.Data;
#Data
public class ApiExceptionInfo {
private int code;
private String message;
}
ApiException is custom exception type in my application:
import lombok.Getter;
public class ApiException extends RuntimeException {
#Getter
private final ApiExceptionInfo info;
public ApiException(ApiExceptionInfo info, Exception cause) {
super(info.toString(), cause);
this.info = info;
}
}
[At least with Resteasy] there is one big disadvantage with the solution offered by #Chuck M and based on ClientResponseFilter.
When you use it based on ClientResponseFilter, your BadRequestException, NotAuthorizedException, ... exceptions are wrapped by javax.ws.rs.ProcessingException.
Clients of your proxy must not be forced to catch this javax.ws.rs.ResponseProcessingException exception.
Without filter, we get an original rest exception. If we catch and handle by default, it does not give us much:
catch (WebApplicationException e) {
//does not return response body:
e.toString();
// returns null:
e.getCause();
}
The problem can be solved on another level, when you extract a description from the error. WebApplicationException exception, which is a parent for all rest exceptions, contains javax.ws.rs.core.Response. Just write a helper method, that in case the exception is of WebApplicationException type, it will also check the response body. Here is a code in Scala, but the idea should be clear. The methord returns a clear description of the rest exception:
private def descriptiveWebException2String(t: WebApplicationException): String = {
if (t.getResponse.hasEntity)
s"${t.toString}. Response: ${t.getResponse.readEntity(classOf[String])}"
else t.toString
}
Now we move a responsibility to show exact error, on the client. Just use a shared exception handler to minimize effort for clients.
The following works for me
Response.status(Response.Status.BAD_REQUEST).entity(e.getMessage()).build();