使用MockRestServiceServer进行Gzip压缩

Question

I have a Java application built on Spring 3.2.0 performing an external call to a REST api serving JSON data.

The call is performed by the Spring RestTemplate class, with Jackson 2.2.3 as serializer/deserializer.

The call is functionnal and supports both plain and gzipped responses.

In order to Junit test the call, I use MockRestServiceServer . Everything works well, until I try to introduce gzip compression. I was unable to find in the offical doc how to activate gzip compression in MockRestServiceServer, so I went the manual route :

• manually gzip the String content of the response

• set the "Content-Encoding" to "gzip" in the headers

Unfortunately, I get the same error again and again, thrown by Jackson when deserializing the response body :

 org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\\r, \\n, \\t) is allowed between tokens at [Source: java.io.ByteArrayInputStream@110d68a; line: 1, column: 2]; nested exception is com.fasterxml.jackson.core.JsonParseException: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\\r, \\n, \\t) is allowed between tokens 

Here is the current code (reworked due to corporate data...)

Test class

 public class ImportRefCliCSTest { @Autowired private MyService myService; private MockRestServiceServer mockServer; @Before public void before() { mockServer = MockRestServiceServer.createServer(myService.getRestTemplate()); } @Test public void testExternalCall() throws IOException { String jsonData = "[{\\"testing\\":\\"Hurray!\\"}]"; HttpHeaders headers = new HttpHeaders(); headers.add( "Content-Encoding", "gzip" ); DefaultResponseCreator drc = withSuccess( gzip( jsonData ), MediaType.APPLICATION_JSON ).headers( headers ); mockServer.expect( requestTo( myService.EXTERNAL_CALL_URL ) ) .andExpect( method( HttpMethod.GET ) ).andRespond(drc); myService.performCall(); } private static String gzip(String str) throws IOException { if (str == null || str.length() == 0) { return str; } ByteArrayOutputStream out = new ByteArrayOutputStream(); GZIPOutputStream gzip = new GZIPOutputStream(out); gzip.write(str.getBytes()); gzip.close(); String outStr = out.toString(); return outStr; } } 

Service class

 @Service public class MyService { public static final String EXTERNAL_CALL_URL = "<myURL>"; private RestTemplate restTemplate; { restTemplate = new RestTemplate(new HttpComponentsClientHttpRequestFactory( HttpClientBuilder.create().build())); } public void performCall() { try { HttpHeaders requestHeaders = new HttpHeaders(); requestHeaders.add("Accept-Encoding", "gzip"); HttpEntity<MyObject[]> requestEntity = new HttpEntity<MyObject[]>(requestHeaders); ResponseEntity<MyObject[]> responseEntity = restTemplate.exchange( EXTERNAL_CALL_URL, HttpMethod.GET, requestEntity, MyObject[].class); MyObject[] array = responseEntity.getBody(); if (array == null || array.length == 0) { return null; } return null; } catch (RestClientException e) { return null; } } public RestTemplate getRestTemplate(){ return restTemplate; } } 

I feel I am missing something. The manual gzip compression seems rather suspicious.

Does anyone have an idea on this ?

Thanks in advance for your answers !

Answer 1

When program convert gzip content to string, some bytes are collapsed. So client cannot decompress it and throw Exception. A solution is return byte[] :

private static byte[] gzip(String str) throws IOException {
    if (str == null || str.length() == 0) {
        return new byte[0];
    }
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(out);
    gzip.write(str.getBytes());//consider to use str.getBytes("UTF-8")
    gzip.close();
    return out.toByteArray();
}