Here's a code excerpt we're using in our app to set request headers. You'll note we set the CONTENT_TYPE header only on a POST or PUT, but the general method of adding headers (via a request interceptor) is used for GET as well.
/**
* HTTP request types
*/
public static final int POST_TYPE = 1;
public static final int GET_TYPE = 2;
public static final int PUT_TYPE = 3;
public static final int DELETE_TYPE = 4;
/**
* HTTP request header constants
*/
public static final String CONTENT_TYPE = "Content-Type";
public static final String ACCEPT_ENCODING = "Accept-Encoding";
public static final String CONTENT_ENCODING = "Content-Encoding";
public static final String ENCODING_GZIP = "gzip";
public static final String MIME_FORM_ENCODED = "application/x-www-form-urlencoded";
public static final String MIME_TEXT_PLAIN = "text/plain";
private InputStream performRequest(final String contentType, final String url, final String user, final String pass,
final Map<String, String> headers, final Map<String, String> params, final int requestType)
throws IOException {
DefaultHttpClient client = HTTPClientFactory.newClient();
client.getParams().setParameter(HttpProtocolParams.USER_AGENT, mUserAgent);
// add user and pass to client credentials if present
if ((user != null) && (pass != null)) {
client.getCredentialsProvider().setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(user, pass));
}
// process headers using request interceptor
final Map<String, String> sendHeaders = new HashMap<String, String>();
if ((headers != null) && (headers.size() > 0)) {
sendHeaders.putAll(headers);
}
if (requestType == HTTPRequestHelper.POST_TYPE || requestType == HTTPRequestHelper.PUT_TYPE ) {
sendHeaders.put(HTTPRequestHelper.CONTENT_TYPE, contentType);
}
// request gzip encoding for response
sendHeaders.put(HTTPRequestHelper.ACCEPT_ENCODING, HTTPRequestHelper.ENCODING_GZIP);
if (sendHeaders.size() > 0) {
client.addRequestInterceptor(new HttpRequestInterceptor() {
public void process(final HttpRequest request, final HttpContext context) throws HttpException,
IOException {
for (String key : sendHeaders.keySet()) {
if (!request.containsHeader(key)) {
request.addHeader(key, sendHeaders.get(key));
}
}
}
});
}
//.... code omitted ....//
}