Custom Request Header (custom HTTP headers) when calling the rest service using spring resttemplate)

In Spring 3.0, you can use the HttpEntity object to customize request header information, such:

private static final String APPLICATION_PDF = "application/pdf"; RestTemplate restTemplate = new RestTemplate(); @Testpublic void acceptHeaderUsingHttpEntity() throws Exception {  HttpHeaders headers = new HttpHeaders();  headers.setAccept(singletonList(MediaType.valueOf(APPLICATION_PDF)));   ResponseEntity<byte[]> response = restTemplate.exchange("http://example.com/file/123",      GET,      new HttpEntity<byte[]>(headers),      byte[].class);   String responseText = PdfTextExtractor.getTextFromPage(new PdfReader(response.getBody()), 1);  assertEquals("Some text in PDF file", responseText);}

In Spring 3.1, there is a more powerful alternative interface ClientHttpRequestInterceptor, which has only one method:Intercept (HttpRequest
Request, byte [] body, ClientHttpRequestExecution execution ),The following is an example:

private static final String APPLICATION_PDF = "application/pdf"; RestTemplate restTemplate = new RestTemplate(); @Testpublic void acceptHeaderUsingHttpRequestInterceptors() throws Exception {  ClientHttpRequestInterceptor acceptHeaderPdf = new AcceptHeaderHttpRequestInterceptor(      APPLICATION_PDF);   restTemplate.setInterceptors(singletonList(acceptHeaderPdf));   byte[] response = restTemplate.getForObject("http://example.com/file/123", byte[].class);   String responseText = PdfTextExtractor.getTextFromPage(new PdfReader(response), 1);  assertEquals("Some text in PDF file", responseText);} class AcceptHeaderHttpRequestInterceptor implements ClientHttpRequestInterceptor {  private final String headerValue;   public AcceptHeaderHttpRequestInterceptor(String headerValue) {    this.headerValue = headerValue;  }   @Override  public ClientHttpResponse intercept(HttpRequest request, byte[] body,      ClientHttpRequestExecution execution) throws IOException {     HttpRequestWrapper requestWrapper = new HttpRequestWrapper(request);    requestWrapper.getHeaders().setAccept(singletonList(MediaType.valueOf(headerValue)));     return execution.execute(requestWrapper, body);  }}

Original article: http://svenfila.wordpress.com/2012/01/05/resttemplate-with-custom-http-headers/