JAX-RS (Reasteasy) Response.readEntity throws: IllegalStateException: RESTEASY003290: Entity is not backed by an input stream
Solution 1
Response
is an abstract class and RESTEasy has different sub classes for client and server, see BuiltResponse
and ClientResponse
. Not all methods are supported in each sub class.
Response#readEntity
needs to be backed by an input stream:
Method throws an
ProcessingException
if the content of the message cannot be mapped to an entity of the requested type andIllegalStateException
in case the entity is not backed by an input stream or if the original entity input stream has already been consumed withoutbuffering
the entity data prior consuming.
A BuiltResponse
is never backed by an input stream and therefore you get a IllegalStateException
.
You can use Response#getEntity
, it doesn't need an input stream.
Solution 2
Thanks for the hint.
I ended up with the following that worked for me. Simply return a new instance of the class below.
class MockResponse extends BuiltResponse {
private Object entity;
public MockResponse() {
}
public MockResponse(Object entity) {
this.entity = entity;
}
@Override
public <T> T readEntity(Class<T> type) {
return (T) entity;
}
@Override
public <T> T readEntity(Class<T> type, Type genericType, Annotation[] anns) {
return (T) entity;
}
}
Solution 3
Today I went through the same situation. Finally I have the below solution. Just mock the readEntity method in BuiltResponse to return whatever response you need. It worked for me.
Niels
Updated on June 14, 2022Comments
-
Niels almost 2 years
I have JUnit test of a method which send a JAX-RS
POST
call. To be independent from external resources I have mocked the REST client and said that a dummy response should be returned. Works great, no problem. But:When calling
myResponse.readEntity(String.class)
I always get the following Exception:java.lang.IllegalStateException: RESTEASY003290: Entity is not backed by an input stream
Here is my code snippet which fails:
import com.google.gson.JsonObject; import com.google.gson.JsonPrimitive; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; import static org.hamcrest.CoreMatchers.is; import static org.hamcrest.MatcherAssert.assertThat; import org.junit.Test; public class SimpleTest { @Test public void testReadResponse() { final JsonObject responseContent = new JsonObject(); responseContent.add("field", new JsonPrimitive("This is a JSON for testing.")); final String expected = responseContent.toString(); final Response.ResponseBuilder builder = Response.ok() .entity(responseContent.toString()) .header("Content-Type", MediaType.APPLICATION_JSON); final Response dummyResponse = builder.build(); final String result = dummyResponse.readEntity(String.class); // <-- Exception is thrown here! assertThat("JSON Strings are not identical.", result, is(expected)); } }
and the Stacktrace:
java.lang.IllegalStateException: RESTEASY003290: Entity is not backed by an input stream at org.jboss.resteasy.specimpl.BuiltResponse.readEntity(BuiltResponse.java:230) at org.jboss.resteasy.specimpl.BuiltResponse.readEntity(BuiltResponse.java:219) at de.me.myproject.SimpleTest.testReadResponse(SimpleTest.java:43)
In my production code, which calls a not mocked REST API, it returns a automatically build response, where the
.readEntity(String.class)
method works fine. -
Pang about 7 years
-
SSK over 6 yearsCreating a mockResponse like above is not helping me. Not sure where am I going wrong :(
-
timekeeper over 5 yearsgetEntity() does solve the problem. Adding to getEntity(), one can typecast the getEntity() response into custom POJO and then use the usual getXXX() to perform
assertEquals(typecastedResponse.getXXX(), expected)