I have application which connects to server via RestClient. And I want to implement right error handling approach there, specifically, ConnectException and HttpHostConnectException if user lost internet connection.
I implemented AsyncTask class in RestClient with all PUT,GET,POST,DELETE methods and handling the result there. And I want to throw my own exception, for example NoInternetConnection if user get exception matching above. And handle my own exception, reloading current Activity and showing message “No Internet” message.
I tried to handle HttpHostConnectException in RestClient and throw my NoInternetConnection and catch it in my Activity but I got
Unreachable catch block for NoInternetException. This exception is never thrown from the try statement body
That’s mean that I should throw my exception from the try statement of Activity. I tried to use static variable of error and throw the exception from Activity if this variable is true from RestClient. But I don’t think it is the best approach.
One more thought was to hanle all the errors in RestClient class, but it is not an Activity and I should use Handler or somethink like that to determine the current Activity and show my Toast message of internet losing.
Tell me please what is the best approach.
My RestClient class:
public class RestClient
{
class AsyncExecute extends AsyncTask<RequestMethod, InputStream, Object>
{
protected InputStream doInBackground(RequestMethod... param) {
HttpUriRequest request;
HttpResponse httpResponse;
DefaultHttpClient client = getNewHttpClient();
InputStream instream = null;
RestClient.this.AddHeader(CoreProtocolPNames.USER_AGENT, "Android-AEApp,ID=2435743");
RestClient.this.AddHeader(ClientPNames.COOKIE_POLICY, CookiePolicy.RFC_2109);
RestClient.this.AddHeader("User-Agent", "Android-AEApp,ID=2435743");
RestClient.this.AddHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
if (CookieStorage.getInstance().getArrayList().isEmpty())
CookieStorage.getInstance().getArrayList().add("PHPSESSID=lc89a2uu0rj6t2p219gc2cq4i2");
RestClient.this.AddHeader("Cookie", CookieStorage.getInstance().getArrayList().get(0).toString());
switch(param[0]) {
case GET:
{
//add parameters
String combinedParams = "";
if(!params.isEmpty()){
combinedParams += "?";
for(NameValuePair p : params)
{
String paramString = null;
try {
paramString = p.getName() + "=" + URLEncoder.encode(p.getValue(),"UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(combinedParams.length() > 1)
{
combinedParams += "&" + paramString;
}
else
{
combinedParams += paramString;
}
}
}
request = new HttpGet(url + combinedParams);
//add headers
for(NameValuePair h : headers)
{
request.addHeader(h.getName(), h.getValue());
}
// executeRequest(request, url);
break;
}
case POST:
{
request = new HttpPost(url);
//add headers
for(NameValuePair h : headers)
{
request.addHeader(h.getName(), h.getValue());
}
if(!params.isEmpty()){
try {
((HttpEntityEnclosingRequestBase) request).setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
break;
}
case PUT:
{
request = new HttpPut(url);
//add headers
for(NameValuePair h : headers)
{
request.addHeader(h.getName(), h.getValue());
}
if(!params.isEmpty()){
try {
((HttpEntityEnclosingRequestBase) request).setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
break;
}
case DELETE:
{
request = new HttpDelete(url);
//add headers
for(NameValuePair h : headers)
{
request.addHeader(h.getName(), h.getValue());
}
if(!params.isEmpty()){
try {
((HttpEntityEnclosingRequestBase) request).setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//executeRequest(request, url);
break;
}
default:
request = null;
}
try {
httpResponse = client.execute(request);
if (httpResponse.getLastHeader("Set-Cookie")!=null)
{
CookieStorage.getInstance().getArrayList().remove(0);
CookieStorage.getInstance().getArrayList().add(httpResponse.getLastHeader("Set-Cookie").getValue());
}
responseCode = httpResponse.getStatusLine().getStatusCode();
message = httpResponse.getStatusLine().getReasonPhrase();
Header[] headers = httpResponse.getAllHeaders();
for(Header head : headers)
{
Log.i("RestClient headers", head.toString());
}
Log.i("RestClient response status code", Integer.toString(responseCode));
if (responseCode == 401)
{
Intent i = new Intent(context,
LoginActivity.class);
i.putExtra("relogin", true);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
}
HttpEntity entity = httpResponse.getEntity();
if (entity != null) {
instream = entity.getContent();
}
} catch (ClientProtocolException e) {
client.getConnectionManager().shutdown();
e.printStackTrace();
}
catch (IOException e) {
client.getConnectionManager().shutdown();
publishProgress();
e.printStackTrace();
}
return instream;
}
protected void onProgressUpdate(Void... progress) {
Toast.makeText(context, "You've lost internet connection. You should try later.",Toast.LENGTH_LONG)
.show();
}
protected void onPostExecute(Object result) {
if(result instanceof Exception) {
try {
throw new NoInternetException();
} catch (NoInternetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else{
super.onPostExecute((InputStream) result);
}
}
}
public InputStream Execute(RequestMethod method) throws Exception
{
AsyncExecute mt = new AsyncExecute();
mt.execute(method);
InputStream stream = (InputStream) mt.get();
return stream;
}
}
I think that if you have errors (or success to report you should do it from RestClient – as you say you will need a way to address the UI thread using the standard handler techniques.
Using a static singleton is generally considered an anti-pattern and is probably a bad idea.