I am using several layers of classes to fetch data from internet and display in Android app.
Activity - ViewModel - Repository - NetworkDataSource ----// Internet
I handle HTTP error messages in NetworkDataSource, where I have try/catch block. However, I would like to propagate this error message to Activity, where I would display a Toast.
How to fire an event in the Activity from NetworkDataSource class?
static String getResponseFromHttpUrl(URL url) throws IOException {
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
String response = "";
try {
urlConnection.setConnectTimeout(5000);
int responseCode = urlConnection.getResponseCode();
switch (responseCode) {
case HttpURLConnection.HTTP_OK:
response = getPayload(urlConnection);
break;
case HttpURLConnection.HTTP_UNAVAILABLE:
throw new IOException("HTTP_UNAVAILABLE");
case HttpURLConnection.HTTP_NOT_FOUND:
throw new IOException("HTTP_NOT_FOUND");
case HttpURLConnection.HTTP_GATEWAY_TIMEOUT:
throw new IOException("HTTP_GATEWAY_TIMEOUT");
}
} catch (IOException e) {
Log.v(TAG, e.getMessage());
throw new IOException(e.getMessage());
} finally {
urlConnection.disconnect();
}
return response;
}
You can use the eventbus. BY eventbus you can send event and can receive ay anyplace you want in the app on whichever thread you want.
https://github.com/greenrobot/EventBus
You can use Interface callbacks/RxJava in addition to EventBus as pointed out by Kirtan.
Related
I am trying to throw a timeout exception in the code below. I tried a simple condition but it's not the proper way.
My question is how can I distinct the timeout exception from SOAPException?
URL endpoint = new URL(null,
urlStr,
new URLStreamHandler() {
// The url is the parent of this stream handler, so must create clone
protected URLConnection openConnection(URL url) throws IOException {
URL cloneURL = new URL(url.toString());
HttpURLConnection cloneURLConnection = (HttpURLConnection) cloneURL.openConnection();
// TimeOut settings
cloneURLConnection.setConnectTimeout(10000);
cloneURLConnection.setReadTimeout(10000);
return cloneURLConnection;
}
});
try {
response = connection.call(request, endpoint);
} catch (SOAPException soapEx) {
if(soapEx.getMessage().contains("Message send failed")) {
throw new TimeoutExpirationException();
} else {
throw soapEx;
}
}
The following lines are from open jdk source code of call method. In the code they are only catching with Exception (also with chaining? comment). I don't think there is other way unless Oracle jdk handles this differently.
You can still try something like if(soapEx.getCause() instanceof SomeTimeoutException) (not sure if this will work)
try {
SOAPMessage response = post(message, (URL)endPoint);
return response;
} catch (Exception ex) {
// TBD -- chaining?
throw new SOAPExceptionImpl(ex);
}
If you want to check the source code HttpSoapConnection
After some hours of testing I found the proper way to distict the SOAPException from Timeout related exceptions. So the solution is to take the parent cause field of the exception and check if it's an instance of SocketTimeoutException.
try {
response = connection.call(request, endpoint);
} catch (SOAPException soapEx) {
if(soapEx.getCause().getCause() instanceof SocketTimeoutException) {
throw new TimeoutExpirationException(); //custom exception
} else {
throw soapEx;
}
}
I am trying to run an Espresso test for my android app, but there is a problem that has been troubling me. In MainActivity, some views' visibility depends on data loaded from net, but in MainActivityTest, I can't manipulate the process of loading data, so I don't know the real data and which view should show and which view should not show. As a result, I don't know how to continue my test. Anyone can tell me how to handle this situation? Thanks!
Try using the MockWebServer library. It lets you mock http responses in your tests, like this:
/**
* Constructor for the test. Set up the mock web server here, so that the base
* URL for the application can be changed before the application loads
*/
public MyActivityTest() {
MockWebServer server = new MockWebServer();
try {
server.start();
} catch (IOException e) {
e.printStackTrace();
}
//Set the base URL for the application
MyApplication.sBaseUrl = server.url("/").toString();
//Create a dispatcher to handle requests to the mock web server
Dispatcher dispatcher = new Dispatcher() {
#Override
public MockResponse dispatch(RecordedRequest recordedRequest) throws InterruptedException {
try {
//When the activity requests the profile data, send it this
if(recordedRequest.getPath().startsWith("/users/self")) {
String fileName = "profile_200.json";
InputStream in = this.getClass().getClassLoader().getResourceAsStream(fileName);
String jsonString = new String(ByteStreams.toByteArray(in));
return new MockResponse().setResponseCode(200).setBody(jsonString);
}
//When the activity requests the image data, send it this
if(recordedRequest.getPath().startsWith("/users/self/media/recent")) {
String fileName = "media_collection_model_test.json";
InputStream in = this.getClass().getClassLoader().getResourceAsStream(fileName);
String jsonString = new String(ByteStreams.toByteArray(in));
return new MockResponse().setResponseCode(200).setBody(jsonString);
}
} catch (IOException e) {
e.printStackTrace();
}
return new MockResponse().setResponseCode(404);
}
};
server.setDispatcher(dispatcher);
}
I am creating a very basic webserver using netty and java. I will have basic functionality. It's main responsibilities would be to serve responses for API calls done from a client (e.g a browser, or a console app I am building) in JSON form or send a zip file. For that reason I have created the HttpServerHanddler class which is responsible for getting the request, parsing it to find the command and call the appropriate api call.It extends SimpleChannelInboundHandler
and overrides the following functions;
#Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
LOG.debug("channelActive");
}
#Override
public void channelReadComplete(ChannelHandlerContext ctx) {
LOG.debug("In channelComplete()");
ctx.flush();
}
#Override
public void channelRead0(ChannelHandlerContext ctx, Object msg)
throws IOException {
ctx = processMessage(ctx, msg);
if (!HttpHeaders.isKeepAlive(request)) {
// If keep-alive is off, close the connection once the content is
// fully written.
ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(
ChannelFutureListener.CLOSE);
}
}
private ChannelHandlerContext processMessage(ChannelHandlerContext ctx, Object msg){
if (msg instanceof HttpRequest) {
HttpRequest request = this.request = (HttpRequest) msg;
if (HttpHeaders.is100ContinueExpected(request)) {
send100Continue(ctx);
}
//parse message to find command, parameters and cookies
ctx = executeCommand(command, parameters, cookies)
}
if (msg instanceof LastHttpContent) {
LOG.debug("msg is of LastHttpContent");
if (!HttpHeaders.isKeepAlive(request)) {
// If keep-alive is off, close the connection once the content is
// fully written.
ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(
ChannelFutureListener.CLOSE);
}
}
return ctx;
}
private ChanndelHandlerContext executeCommand(String command, HashMap<String, List<String>>> parameters, Set<Cookie> cookies>){
//switch case to see which command has to be invoked
switch(command){
//many cases
case "/report":
ctx = myApi.getReport(parameters, cookies); //This is a member var of ServerHandler
break;
//many more cases
}
return ctx;
}
In my Api class that has the getReport function.
getReport
public ChannelHandlerContext getReportFile(Map<String, List<String>> parameters,
Set<Cookie> cookies) {
//some initiliazations. Actual file handing happens bellow
File file = new File(fixedReportPath);
RandomAccessFile raf = null;
long fileLength = 0L;
try {
raf = new RandomAccessFile(file, "r");
fileLength = raf.length();
LOG.debug("creating response for file");
this.response = Response.createFileResponse(fileLength);
this.ctx.write(response);
this.ctx.write(new HttpChunkedInput(new ChunkedFile(raf, 0,
fileLength,
8192)),
this.ctx.newProgressivePromise());
} catch (FileNotFoundException fnfe) {
LOG.debug("File was not found", fnfe);
this.response = Response.createStringResponse("failure");
this.ctx.write(response);
} catch (IOException ioe) {
LOG.debug("Error getting file size", ioe);
this.response = Response.createStringResponse("failure");
this.ctx.write(response);
} finally {
try {
raf.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return this.ctx;
}
Response class is responsible for handling various types of response creations (JsonString JsonArray JsonInteger File, etc)
public static FullHttpResponse createFileResponse(long fileLength) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
HttpHeaders.setContentLength(response, fileLength);
response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "application/octet-stream");
return response;
}
My Api works great for my Json responses(easier to achieve) but It won't work well with my json responses, but not with my file response. When making a request from e.g chrome it only hangs and does not download the file. Should I do something else when downloading a file using netty? I know its not the best wittern code, I still think I have some bits and pieces missing from totally understanding the code, but I would like your advice on how to handle download on my code. For my code I took under consideration this and this
First, some remarks on your code...
Instead of returning ctx, I would prefer to return the last Future for the last command, such that your last event (no keep alive on) could use it directly.
public void channelRead0(ChannelHandlerContext ctx, Object msg)
throws IOException {
ChannelFuture future = processMessage(ctx, msg);
if (future != null && !HttpHeaders.isKeepAlive(request)) {
// If keep-alive is off, close the connection once the content is
// fully written.
future.addListener(ChannelFutureListener.CLOSE);
}
}
Doing this way will allow to directly close without having any "pseudo" send, even empty.
Important: Note that in Http, the response is managed such that there are chunk send for all data after the first HttpResponse item, until the last one which is empty (LastHttpContent). Sending another empty one (Empty chunk but not LastHttpContent) could break the internal logic.
Moreover, you're doing the work twice (once in read0, once in processMessage), which could lead to some issues perhaps.
Also, since you check for KeepAlive, you should ensure to set it back in the response:
if (HttpHeaders.isKeepAlive(request)) {
response.headers().set(CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
}
On your send, you have 2 choices (depending on the usage of SSL or not): you've selected only the second one, which is more general, so of course valid in all cases but less efficient.
// Write the content.
ChannelFuture sendFileFuture;
ChannelFuture lastContentFuture;
if (ctx.pipeline().get(SslHandler.class) == null) {
sendFileFuture =
ctx.write(new DefaultFileRegion(raf.getChannel(), 0, fileLength), ctx.newProgressivePromise());
// Write the end marker.
lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT); // <= last writeAndFlush
} else {
sendFileFuture =
ctx.writeAndFlush(new HttpChunkedInput(new ChunkedFile(raf, 0, fileLength, 8192)),
ctx.newProgressivePromise()); // <= last writeAndFlush
// HttpChunkedInput will write the end marker (LastHttpContent) for us.
lastContentFuture = sendFileFuture;
}
This is this lastContentFuture that you can get back to the caller to check the KeepAlive.
Note however that you didn't include a single flush there (except with your EMPTY_BUFFER but which can be the main reason of your issue there!), contrary to the example (from which I copied the source).
Note that both use a writeAndFlush for the last call (or the unique one).
My app is crashing unpredictably and I don't understand why. I'm using HttpURLConnection to retrieve a json file and I'm trying to use the JsonReader class to read from, and use that file. The trouble is that the application crashes after reading or doing anything to the instance of JsonReader.
I've read the input stream with scanner but that causes a similar problem. However when reading with the scanner I can print small amounts of json from the server. So the data from the server is probably making it into the JsonReader as well.
This is my code:
public class ConnectToServer implements Runnable {
private URL connectionUrl;
private MainActivity output;
public ConnectToServer(URL url, MainActivity mainActivity) {
connectionUrl = url;
output = mainActivity;
}
public void printError(String errorMessage){
output.output(errorMessage);
}
public InputStream GetInputStream(){
try {
HttpURLConnection connection = (HttpURLConnection)connectionUrl.openConnection();
InputStream inputStream = new BufferedInputStream(connection.getInputStream());
if (inputStream == null){
printError("Input stream is null");
}
return inputStream;
} catch (IOException ex){
printError("IO exception has been thrown");
} catch (Exception ex){
printError("Normal exception thrown: " + ex.getClass().getSimpleName());
}
return null;
}
#Override
public void run() {
InputStream inputStream = GetInputStream();
try {
if (inputStream == null){
printError("Input stream not initiated");
} else {
JsonReader reader = new JsonReader(new InputStreamReader(inputStream, "UTF-8"));
printError(reader.toString());
reader.close();
}
} catch (Exception ex){
printError("Exception while printing input stream: " + ex.getClass().getSimpleName());
}
printError("Thread finished");
}
This gets run on a thread created in the main UI thread.
public void connect(){
output("connect started");
boolean success = true;
try {
URL url = new URL("http://geonews.azurewebsites.net/api/Location");
serverConnection = new ConnectToServer(url,this);
Thread thread = new Thread(serverConnection);
thread.start();
} catch (MalformedURLException ex){
output("Messed up the URL");
success = false;
}
if (success){
output("Thread has been started");
} else {
output("exception was thrown while trying to run thread");
}
}
Does anybody know why this code would be causing my app to crash? Even if it gets to "Thread finished" it will crash soon after.
Btw I realise I should be using AsyncTask but I've already gone down this track and I'd rather get this going first.
Logcat:
06-14 22:45:00.058 4032-4052/com.tomsapps.thomas.jsonreadertestapp E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-314
Process: com.tomsapps.thomas.jsonreadertestapp, PID: 4032
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6247)
at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:867)
at android.view.View.requestLayout(View.java:17364)
at android.view.View.requestLayout(View.java:17364)
at android.view.View.requestLayout(View.java:17364)
at android.view.View.requestLayout(View.java:17364)
at android.view.View.requestLayout(View.java:17364)
at android.view.View.requestLayout(View.java:17364)
at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:360)
at android.view.View.requestLayout(View.java:17364)
at android.widget.TextView.checkForResize(TextView.java:6798)
at android.widget.TextView.updateAfterEdit(TextView.java:7693)
at android.widget.TextView.handleTextChanged(TextView.java:7709)
at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:9440)
at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:964)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:515)
at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:272)
at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:33)
at android.widget.TextView.append(TextView.java:3616)
at android.widget.TextView.append(TextView.java:3603)
at com.tomsapps.thomas.jsonreadertestapp.MainActivity.output(MainActivity.java:63)
at com.tomsapps.thomas.jsonreadertestapp.ConnectToServer.printError(ConnectToServer.java:26)
at com.tomsapps.thomas.jsonreadertestapp.ConnectToServer.run(ConnectToServer.java:74)
at java.lang.Thread.run(Thread.java:818)
I believe your output method from MainActivity modifies a TextView, therefore triggering the exception.
A view hierarchy can only be changed from the "Main" thread, in this case, you might want to try looking into runOnUiThread , some resources on StackOverflow :
how to use runOnUiThread
Android runOnUiThread explanation
Android Java runOnUiThread()
Hope this helps, good luck :)
Edit :
You might also want to use android Log instead of using TextView to display the errors.
I am taking some data from a database via a servlet and a db handler java class and hosting it at a url. Since the database is changing I'm taking care only to host the changes rather than the entire db data.
I'm getting the required functionality by a browser i.e after every (manual) reload, I'm getting the data as required by me,
1. at the first page load, entire data gets displayed.
2. at subsequent reloads, I get either null data if there is no change in the database, or the appended rows if the database extends. (the database can only extend).
But then in a java program, I'm not getting the same functionality. The java program using HttpUrlConnection.
This is the code for the java client for servlet...
public class HTTPClient implements Runnable {
private CallbackInterface callbackinterface;
private URL url;
private HttpURLConnection http;
private InputStream response;
private String previousMessage = "";
public HTTPClient() {
try {
url = new URL("http://localhost:8080/RESTful-Server/index.jsp");
http = (HttpURLConnection) url.openConnection();
http.connect();
} catch (IOException e) {
}
}
#Override
public void run() {
while (true) {
try {
String currentmessage = "";
response = http.getInputStream();
if (http.getResponseCode() == HttpURLConnection.HTTP_OK) {
BufferedReader buffread = new BufferedReader(new InputStreamReader(response));
String line;
for (; (line = buffread.readLine()) != null;) {
currentmessage += line;
}
if ((!currentmessage.equals(previousMessage)
|| !previousMessage.equals(""))
&& !currentmessage.equals("")) {
//this.callbackinterface.event(currentmessage);\
System.out.println(currentmessage + "\t" + previousMessage);
}
previousMessage = currentmessage;
Thread.sleep(2500);
} else {
throw new IOException();
}
} catch (IOException | InterruptedException e) {
System.err.println("Exception" + e);
}
}
}
The shown class is a thread which read the connections every 2.5 s. If it gets something significant in the getline(), it will issue a callback to a worker method, which takes care of remaining things.
I am thinking the issues is because of the class variable conn, and that reload as in the browser is not getting replicated..
Any idea how to do this?
You're basically connecting (requesting) only once and trying to read the response multiple times, while it can be read only once. You basically need to create a new connection (request) everytime. You need to move the creation of the connection by url.openConnection() to inside the loop. The line http.connect() is by the way superfluous. You can safely omit it. The http.getInputStream() will already implicitly do it.
See also:
Using java.net.URLConnection to fire and handle HTTP requests