Reading responses
editReading responses
editThe Response
object, either returned by the synchronous performRequest
methods or
received as an argument in ResponseListener#onSuccess(Response)
, wraps the
response object returned by the http client and exposes some additional information.
Response response = restClient.performRequest(new Request("GET", "/")); RequestLine requestLine = response.getRequestLine(); HttpHost host = response.getHost(); int statusCode = response.getStatusLine().getStatusCode(); Header[] headers = response.getHeaders(); String responseBody = EntityUtils.toString(response.getEntity());
Information about the performed request |
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The host that returned the response |
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The response status line, from which you can for instance retrieve the status code |
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The response headers, which can also be retrieved by name though |
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The response body enclosed in an |
When performing a request, an exception is thrown (or received as an argument
in ResponseListener#onFailure(Exception)
in the following scenarios:
-
IOException
- communication problem (e.g. SocketTimeoutException)
-
ResponseException
-
a response was returned, but its status code indicated
an error (not
2xx
). AResponseException
originates from a valid http response, hence it exposes its correspondingResponse
object which gives access to the returned response.
A ResponseException
is not thrown for HEAD
requests that return
a 404
status code because it is an expected HEAD
response that simply
denotes that the resource is not found. All other HTTP methods (e.g., GET
)
throw a ResponseException
for 404
responses unless the ignore
parameter
contains 404
. ignore
is a special client parameter that doesn’t get sent
to Elasticsearch and contains a comma separated list of error status codes.
It allows to control whether some error status code should be treated as an
expected response rather than as an exception. This is useful for instance
with the get api as it can return 404
when the document is missing, in which
case the response body will not contain an error but rather the usual get api
response, just without the document as it was not found.
Note that the low-level client doesn’t expose any helper for json marshalling and un-marshalling. Users are free to use the library that they prefer for that purpose.
The underlying Apache Async Http Client ships with different
org.apache.http.HttpEntity
implementations that allow to provide the request body in different formats
(stream, byte array, string etc.). As for reading the response body, the
HttpEntity#getContent
method comes handy which returns an InputStream
reading from the previously buffered response body. As an alternative, it is
possible to provide a custom
org.apache.http.nio.protocol.HttpAsyncResponseConsumer
that controls how bytes are read and buffered.