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try with resources in a method used by another one

I have the following java code with try with resources:
public static CloseableHttpResponse getHttpResponse()
{
try (CloseableHttpClient client = HttpClientBuilder.create().build()) {
try (CloseableHttpResponse response = client.execute(request)) {
return response;
}
}
}
in another method will use the response returned by getHttpResponse:
public void test() {
CloseableHttpResponse response = getHttpResponse();
if (response) {
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == HttpStatus.SC_OK) {
// do something
}
}
}
Looks like after CloseableHttpResponse response = getHttpResponse();, the client and response already closed, and I can not put this two methods into one, are there any ways that still use the try with resources in another method?

The best approach is the Execute Around idiom. Instead of getHttpResponse returning a CloseableHttpResponse pass in a lambda (typically) to be executed. The resource can then be closed in a try-with-resource statement cleanly.
/*** NICE ***/
// Function instead of Consumer would allow the method to return a value.
private void httpResponse(
Consumer<CloseableHttpResponse> op
) /* throws IOException */ {
try (CloseableHttpClient client = HttpClientBuilder.create().build()) {
try (CloseableHttpResponse response = client.execute(request)) {
if (response != null) { // Really?
op.accept(response);
}
}
}
}
Used as:
httpResponse(response -> {
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == HttpStatus.SC_OK) {
// do something
}
});
The hacky alternative is to include a try statement within getHttpResponse that only closed in error conditions.
/*** HACKY ***/
private CloseableHttpResponse httpResponse() /* throws IOException */ {
boolean success = false;
CloseableHttpClient client = HttpClientBuilder.create().build();
try {
CloseableHttpResponse response = client.execute(request);
try {
success = true;
return response;
} finally {
if (!success) {
response.close();
}
}
} finally {
if (!success) {
client.close();
}
}
}

client will be closed as soon as the program leaves the scope of the try-with-resources. Can you try building the try with resources around the getHttpResponse method? For example:
public static CloseableHttpResponse getHttpResponse() {
try (CloseableHttpClient client = HttpClientBuilder.create().build()) {
CloseableHttpResponse response = client.execute(request)
return response;
}
}
And then you can rewrite your test method() like this:
public void test() {
try(CloseableHttpResponse response = getHttpResponse()) {
if (response) {
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == HttpStatus.SC_OK) {
// do something
}
}
}
}

How to correctly handling HTTP request errors?

I have a simple http client that passes every request to ExecutorService and applies them with a delay.
protected static final int RETRY_ATTEMPTS = 5;
private static final int GROUP_REQUEST_DELAY_MS = 55;
private static final ScheduledExecutorService REQUEST_FROM_USER_EXECUTOR =
Executors.newSingleThreadScheduledExecutor();
public RequestResponse post(String url) throws IOException {
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = call(httpPost);
return new RequestResponse(
httpResponse.getStatusLine().getStatusCode(),
EntityUtils.toString(httpResponse.getEntity()),
headers(httpResponse.getAllHeaders())
);
}
private HttpResponse call(HttpRequestBase request) throws IOException {
int attempts = 0;
HttpResponse httpResponse = null;
SocketException socketException = null;
do {
try {
httpResponse = client.execute(request);
} catch(SocketException e) {
socketException = e;
}
if(httpResponse != null)
break;
attempts++;
log.debug("Attempt: {}, SocEx: {}", attempts, socketException != null);
}while(attempts < RETRY_ATTEMPTS);
if(httpResponse == null)
// TODO
if(socketException != null) {
log.error("Network problem");
logRequest(request, httpResponse);
throw socketException;
}
return httpResponse;
}
public synchronized Future<RequestResponse> sendAsGroup(String url) {
return REQUEST_FROM_GROUP_EXECUTOR.schedule(() -> post(url), GROUP_REQUEST_DELAY_MS, TimeUnit.MILLISECONDS);
}
Sometimes the server throws an http 504 error or so. I want to process this error and resubmit this request. How can I do this correctly without exceeding the limit for server requests?

You should be using HttpRequestRetryHandler to recover from transport level (TCP) errors and ServiceUnavailableRetryStrategy to retry the request execution in case of a protocol level (HTTP) error.

Java (HttpPost, HttpGet, HttpPut, HttpPatch) methods in C#

Following is the code snippet in JAVA.
I want to do the similar thing in C#, Metro apps.
public static String callWebservice(String paramJson) throws Exception {
...
...
DefaultHttpClient httpclient = new DefaultHttpClient();
...
if (requestType.equals("POST") ) {
HttpPost httpPostReq = new HttpPost(url);
StringEntity se = new StringEntity(jsonParam.toString());
se.setContentType("application/json;charset=UTF-8");
se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json;charset=UTF-8"));
httpPostReq.setEntity(se);
httpresponse = httpclient.execute(httpPostReq);
}
else if (requestType.equals("GET") ) {
HttpGet httpGetReq = new HttpGet(url);
...
}
else if (requestType.equals("PUT") ) {
HttpPut httpPutReq = new HttpPut(url);
....
}
else if (requestType.equals("PATCH") ) {
HttpPatch httpPatchReq = new HttpPatch(url);
...
}
responseText = EntityUtils.toString(httpresponse.getEntity());
return responseText;
}
I wonder if there are separate methods of Java: ("HttpPost", "HttpGet", "HttpPut", "HttpPatch" ) in C# also.
I tried to accomplish the task using HttpClient but I'm facing errors while adding headers "Accept", "Content-Type", "X-Security-AuthKey" and throws error like:
Misued header ...
But somehow I managed to add header using "TryAddWithoutValidation".
In my C# code, I have the code snippet like following:
private async Task<string> CallHttpServiceHelper(string json)
{
try
{
...
HttpModel model = JsonConvert.DeserializeObject<HttpModel>(json);
try
{
JsonObject jsonObject = new JsonObject();
jsonObject["userName"] = JsonValue.CreateStringValue(model.paramss.userName);
jsonObject["password"] = JsonValue.CreateStringValue(model.paramss.password);
jsonObject["domain"] = JsonValue.CreateStringValue(model.paramss.domain);
jsonObject["accessKey"] = JsonValue.CreateStringValue(model.paramss.accessKey);
inputParams = jsonObject.Stringify();
}
catch (Exception ex)
{
}
url = model.url;
requestType = model.requesttype;
try
{
authenticationKey = model.authenticationKey;
}
catch (Exception ex)
{
}
if (requestType == "POST")
{
uri = new Uri(url);
data = new StringContent(inputParams, Encoding.UTF8, "application/json");
if (authenticationKey != null && authenticationKey != "")
{
data.Headers.Add("X-Security-AuthKey", authenticationKey);
}
httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.Add("Accept", "application/json");
httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json");
httpClient.Timeout = TimeSpan.FromMinutes(10);
var response = await httpClient.PostAsync(uri, data);
content = await response.Content.ReadAsStringAsync();
httpClient.Dispose();
}
else if (requestType == "GET")
{
uri = new Uri(url);
httpClient = new HttpClient();
if (authenticationKey != null && authenticationKey != "")
{
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("X-Security-AuthKey", authenticationKey);
}
httpClient.DefaultRequestHeaders.Add("Accept", "application/json");
httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json");
httpClient.Timeout = TimeSpan.FromMinutes(10);
var response = await httpClient.GetAsync(uri);
content = await response.Content.ReadAsStringAsync();
httpClient.Dispose();
}
else if (requestType == "PUT")
{
...
}
else if (requestType == "PATCH")
{
...
}
return content;
}
catch (Exception ex)
{
return "fail";
}
}
This code in C#, Windows RT Apps works fine for POST method. But I'm not getting the required response from webservice in GET method. In GET method I have to call WebService by passing three Headers only "Accept", "Content-Type", "X-Security-AuthKey".
I don't know what I'm doing wrong.

grails receive file via MultipartEntity

I use this httpclient to post a image to my grails as follows. How do I receive the file in grails?
public static String webPost(String method, File data, Context c) throws Exception {
String json = "";
if (isOnline(c) == true) {
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response;
HttpPost httppost ;
try {
httppost = new HttpPost(method);
MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
entity.addPart("image", new FileBody(data));
httppost.setEntity(entity);
response = httpclient.execute(httppost);
if (response != null) {
HttpEntity r_entity = response.getEntity();
json = EntityUtils.toString(r_entity);
Log.i("ja", json);
}
} catch (Exception e) {
throw new RuntimeException(e.getLocalizedMessage());
} finally {
httpclient = null;
response = null;
httpclient = null;
}
} else {
throw new RuntimeException("No internet connection");
}
return json;
}
My grails:
def image = request.getFile('image')
image.transferTo(new File('c:/p.png') )
Error:
groovy.lang.MissingMethodException: No signature of method: org.apache.catalina.core.ApplicationHttpRequest.getFile() is applicable for argument types: (java.lang.String) values: [image]
Possible solutions: getXML(), getAt(java.lang.String), getAt(java.lang.String), getLocale(), getInfo(), recycle()
at mclient.TestController$_closure1.doCall(TestController.groovy:10)
at mclient.TestController$_closure1.doCall(TestController.groovy)
at java.lang.Thread.run(Thread.java:662)

DefaultClientConnection automatically gets shutdown

I am new to HttpClient. I am using DefaultHttpClient (which is said to be thread-safe).
In my app I have created two threads which have been scheduled to execute every 10 minutes simultaneously. Sometimes I found that the DefaultClientConnection automatically gets shutdown.
What could be the possible reasons?
Though DefaultHttpClient is thread-safe, shall I need to use PoolingClientConnectionManager in this scenario ?

You should use PoolingClientConnectionManager.
Also you must use IdleConnectionMonitorThread for monitor idle connection.
some code from my source :
private final PoolingClientConnectionManager connectionManager;
private final IdleConnectionMonitorThread connectionMonitorThread = null;
private final DefaultHttpClient httpclient;
initialization:
final HttpParams params = new BasicHttpParams();
final HttpProtocolParamBean paramsBean = new HttpProtocolParamBean(params);
paramsBean.setVersion(HttpVersion.HTTP_1_1);
paramsBean.setContentCharset("UTF-8");
paramsBean.setUseExpectContinue(false);
params.setBooleanParameter(HttpConnectionParams.STALE_CONNECTION_CHECK, false);
params.setIntParameter("http.socket.timeout", 20000);
params.setIntParameter("http.connection.timeout", 30000);
params.setBooleanParameter("http.protocol.handle-redirects", true);
params.setBooleanParameter(HttpConnectionParams.TCP_NODELAY, true);
params.setIntParameter(HttpConnectionParams.SOCKET_BUFFER_SIZE, 32 * 1024);
params.setParameter("http.protocol.cookie-policy", CookiePolicy.BROWSER_COMPATIBILITY);
// params.setParameter("http.useragent", "Crawler Airupt(http://www.airupt.com/)");
params.setParameter("http.useragent",
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_4) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.79 Safari/537.1");
params.setParameter("http.language.Accept-Language", "en-us");
params.setParameter("http.protocol.content-charset", "UTF-8");
params.setParameter("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
params.setParameter("Cache-Control", "max-age=0");
final SSLSocketFactory socketFactory = SSLSocketFactory.getSocketFactory();
final SchemeRegistry schemeRegistry = new SchemeRegistry();
schemeRegistry.register(new Scheme("http", 80, PlainSocketFactory.getSocketFactory()));
schemeRegistry.register(new Scheme("https", 443, socketFactory/* SSLSocketFactory.getSocketFactory() */));
connectionManager = new PoolingClientConnectionManager(schemeRegistry);
connectionManager.setDefaultMaxPerRoute(500000);
connectionManager.setMaxTotal(2000000);
httpclient = new DefaultHttpClient(connectionManager, params);
httpclient.setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
#Override
public long getKeepAliveDuration(final HttpResponse response, final HttpContext context) {
final HeaderElementIterator it = new BasicHeaderElementIterator(response
.headerIterator(HTTP.CONN_KEEP_ALIVE));
while (it.hasNext()) {
final HeaderElement he = it.nextElement();
final String param = he.getName();
final String value = he.getValue();
if (value != null && param.equalsIgnoreCase("timeout")) {
try {
return Long.parseLong(value) * 1000;
} catch (final NumberFormatException ignore) {
}
}
}
return 30 * 1000;
}
});
httpclient.setRedirectStrategy(new DefaultRedirectStrategy());
httpclient.addRequestInterceptor(new HttpRequestInterceptor() {
#Override
public void process(final HttpRequest request, final HttpContext context) throws HttpException, IOException {
if (!request.containsHeader("Accept-Encoding")) {
request.addHeader("Accept-Encoding", "gzip");
}
}
});
httpclient.addResponseInterceptor(new HttpResponseInterceptor() {
#Override
public void process(final HttpResponse response, final HttpContext context) throws HttpException, IOException {
response.setEntity(new BufferedHttpEntity(response.getEntity()));
final HttpEntity entity = response.getEntity();
final Header ceheader = entity.getContentEncoding();
if (ceheader != null) {
final HeaderElement[] codecs = ceheader.getElements();
for (int i = 0; i < codecs.length; i++) {
if (codecs[i].getName().equalsIgnoreCase("gzip")) {
response.setEntity(new GzipDecompressingEntity(response.getEntity()));
return;
}
}
}
}
});
startConnectionMonitorThread();
few addition methods:
private synchronized void startConnectionMonitorThread() {
if (connectionMonitorThread == null) {
connectionMonitorThread = new IdleConnectionMonitorThread(connectionManager);
}
connectionMonitorThread.start();
}
private synchronized void stopConnectionMonitorThread() {
if (connectionMonitorThread != null) {
connectionMonitorThread.shutdown();
connectionManager.shutdown();
}
}
public void shutdown() {
stopConnectionMonitorThread();
final ClientConnectionManager cm = httpclient.getConnectionManager();
if (cm != null) {
httpclient.getConnectionManager().shutdown();
}
}
Using:
final HttpGet httpGet = new HttpGet(url);
final HttpResponse response = httpclient.execute(httpGet);
final StatusLine statusLine = response.getStatusLine();
final int responseCode = statusLine.getStatusCode();
if (responseCode >= 300) {
logger.error(" {}. Received statusCode {}", url, responseCode);
httpGet.abort();
//throw some exception;
}
final HttpEntity entity = response.getEntity();
if (entity == null) {
//throw some exception or ignore;
}
responseBody = EntityUtils.toString(entity);
This code/params optimized for Crawler. to fast receive a lot of pages. with using gzip(if possible) and https if require without using cookies. For addition cookies you need to add cookieStore like httpclient.setCookieStore();