Given a Url for an image, I want to downoload it and paste it onto my canvas in android. How do I retrieve the image into my app ?
Please help.
Thanks,
de costo.
Dont forget to give the app the permission to connect to the Web,
in the AndroidManifest.xml:
<uses-permission android:name="android.permission.INTERNET" />
You can use the following code to download an image:
URLConnection connection = uri.toURL().openConnection();
connection.connect();
InputStream is = connection.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is, 8 * 1024);
Bitmap bmp = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
Requires the following permission in AndroidManifest.xml:
<uses-permission android:name="android.permission.INTERNET" />
There is a an HTTP client library that might be supported in Android now, but for any fine grain control you can use URL & HttpURLConnection. the code will look something like this:
URL connectURL = new URL(<your URL goes here>);
HttpURLConnection conn = (HttpURLConnection)connectURL.openConnection();
// do some setup
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("GET");
// connect and flush the request out
conn.connect();
conn.getOutputStream().flush();
// now fetch the results
String response = getResponse(conn);
where getResponse() looks something like this, in your case you are getting
a pile of binary data back you might want to change the StringBuffer to a byte array
and chunk the reads by a larger increment.
private String getResponseOrig(HttpURLConnection conn)
{
InputStream is = null;
try
{
is = conn.getInputStream();
// scoop up the reply from the server
int ch;
StringBuffer sb = new StringBuffer();
while( ( ch = is.read() ) != -1 ) {
sb.append( (char)ch );
}
return sb.toString();
}
catch(Exception e)
{
Log.e(TAG, "biffed it getting HTTPResponse");
}
finally
{
try {
if (is != null)
is.close();
} catch (Exception e) {}
}
return "";
}
As you are talking about image data which can be large, other things you need to be assiduous about in Android is making sure you release your memory as soon as you can, you've only got 16mb of heap to play with for all apps and it runs out fast and the GC will drive you nuts if you aren't really good about giving back memory resources
Related
String thisurl ="http://songolum.com/file/ppdVkTxqhwcJu-CAzCgtNeICMi8mHZnKQBgnksb5o2Q/Ed%2BSheeran%2B-%2BPerfect.mp3?r=idz&dl=311&ref=ed-sheran-perfect";
url = null;
try {
url = new URL(thisurl);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
// urlConnection.setRequestProperty("Transfer-Encoding", "chunked");
urlConnection.setRequestProperty("Accept-Encoding", "identity");
urlConnection.setDoOutput(true);
urlConnection.setChunkedStreamingMode(0);
int l=0;
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
while(in.read()!=-1)
{
l=l+in.read();
}
System.out.println("Content-length" +l);
**I checked with other software and I found it's gzip compressed file and its with 10mb and I'm getting almost 1mb **
To answer your question directly, you were going wrong because you were calling read() twice, and also because you were adding together the values of each byte read, instead of counting them. InputStream.read() reads one byte and returns its value, or -1 on EOF. You need to read a number of bytes into a buffer and count how many bytes each read() call returned:
InputStream in = urlConnection.getInputStream();
byte[] buffer = new byte[4096];
int countBytesRead;
while((countBytesRead = in.read(buffer)) != -1) {
l += countBytesRead;
}
System.out.println("Content-length: " + l);
However, I suspect that this is not really what you need to do. The above code will simply return the size of all content in the response, including the HTTP headers and the content. Perhaps what you are looking for is the length of the document (or the file to be downloaded). You can use the Content-length HTTP header for that purpose (see other SO questions for how to get HTTP headers).
Also, note that the content may or may not be gzip-compressed. It depends on what the HTTP request says it accepts.
Please try this one hope so it will be helpful for you.
Using a HEAD request, i got my webserver to reply with the correct content-length field which otherwise was wrong. I don't know if this works in general but in my case it does:
private int tryGetFileSize(URL url) {
HttpURLConnection conn = null;
try {
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("HEAD");
conn.getInputStream();
return conn.getContentLength();
} catch (IOException e) {
return -1;
} finally {
conn.disconnect();
}
}
I have a trouble with my HttpsConnection on android.
First of all, no it is not a duplicate. I try almost all the solutions on SO, like changing the keep-alive option or the timeout ( and some of them indeed optimized a part of my code a little bit ) but it is still 5 to 10 times ( probably more ) slower on android than on iOS.
Sending a request to my server takes several seconds on android while it's almost instant on iOS and from a browser. I am sure that the server is not in cause. But it seems that getting the inputstream is terribly slow!
This line:
in=conn.getInputStream();
is the most delaying one, taking several seconds by itself.
My aim is to get a JSON from my server. My code is supposed to be technically as optimized as possible ( and it can probably help some people with HttpsConnection on the same time ):
protected String getContentUrl(String apiURL)
{
StringBuilder builder = new StringBuilder();
String line=null;
String result="";
HttpsURLConnection conn= null;
InputStream in= null;
try {
URL url;
// get URL content
url = new URL(apiURL);
System.setProperty("http.keepAlive", "false");
trustAllHosts();
conn = (HttpsURLConnection) url.openConnection();
conn.setHostnameVerifier(DO_NOT_VERIFY);
conn.setRequestMethod("GET");
conn.setRequestProperty(MainActivity.API_TOKEN, MainActivity.ENCRYPTED_TOKEN);
conn.setRequestProperty("Connection", "close");
conn.setConnectTimeout(1000);
in=conn.getInputStream();
// open the stream and put it into BufferedReader
BufferedReader br = new BufferedReader(new InputStreamReader(in));
while ((line=br.readLine())!= null) {
builder.append(line);
}
result=builder.toString();
//System.out.print(result);
br.close();
} catch (MalformedURLException e) {
result=null;
} catch (IOException e) {
result=null;
} catch (Exception e) {
result=null;
}
finally {
try {
in.close();
}catch(Exception e){}
try {
conn.disconnect();
}catch(Exception e){}
return result;
}
}
However, it keeps taking several seconds.
So I would like to know: is there a way to improve the speed of this API call? The problem is not the server or the JSON parsing but for sure the function above. Thanks a lot.
I'm trying to create an android application which depends on JSON responses. Sometimes it takes a lot of time for the server to respond and ends in a time out exception. Therefore I would like to add a restriction like my webservice call should abort after 20seconds if there is no response. Can you please help me achieving this idea.
Thanks in Advance.
You're not giving much details on the actual implementation that you have.
However, messing with the timeout seems like it may be an emergency fix to an underlying problem that should be fixed.
However, using websockets for transport could be a possible (and probably more elegant) solution. They provide a persistent connection between client and server once created.
Using websockets on Android and IOS
There are several ways to achieve the goal.
We can using HttpURLConnection to do the http request.
public String doPost() {
if (!mIsNetworkAvailable) {
return null;
}
try {
URL url = new URL(mURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setDoOutput(true);
conn.setDoInput(true);
for (String key : mHeadersMap.keySet()) {
conn.setRequestProperty(key, mHeadersMap.get(key));
}
conn.setRequestProperty("User-Agent", "Android");
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setRequestProperty("Content-Type", "application/json");
conn.getOutputStream().write(mContent);
conn.getOutputStream().flush();
int rspCode = conn.getResponseCode();
if (rspCode >= 400) {
return null;
}
byte[] buffer = new byte[8 * 1024];
BufferedInputStream bis = new BufferedInputStream(conn.getInputStream());
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int len;
while ((len = bis.read(buffer)) > 0) {
baos.write(buffer, 0, len);
}
baos.flush();
final String result = new String(baos.toByteArray());
baos.close();
return result;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
setConnectTimeout :Sets the maximum time in milliseconds to wait while connecting.
setReadTimeout:Sets the maximum time to wait for an input stream read to complete before giving up.
Reference: http://developer.android.com/reference/java/net/URLConnection.html
I have a REST service I can't alter, with methods for uploading an image, encoded as a Base64 string.
The problem is that the images can go up to sizes of 5-10MB, perhaps more. When I try to construct a Base64 representation of an image of this size on the device, I get an OutOfMemory exception.
I can however encode chunks of bytes at a time (3000 let's say), but this is useless as I would need the whole string to create a HttpGet/HttpPost object:
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet("www.server.com/longString");
HttpResponse response = client.execute(httpGet);
Is there a way of going around this?
Edit: trying to use Heiko Rupp's suggestions + the android doc, I get an exception ("java.io.FileNotFoundException: http://www.google.com") at the following line: InputStream in = urlConnection.getInputStream();
try {
URL url = new URL("http://www.google.com");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setDoOutput(true);
urlConnection.setChunkedStreamingMode(0);
OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
out.write("/translate".getBytes());
InputStream in = urlConnection.getInputStream();
BufferedReader r = new BufferedReader(new InputStreamReader(in));
StringBuilder total = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
total.append(line);
}
System.out.println("response:" + total);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Am I missing something? The GET request that I need to execute looks like this:
"http://myRESTService.com/myMethod?params=LOOONG-String", so the idea was to connect to http://myRESTService.com/myMethod and then output a few characters of the long string at a time. Is this correct?
You should try to use the URLConnection instead of the apache http client, as this does not require you to hold the object to send in memory, but instead you can do something like:
pseudocode!
HttpUrlConnection con = restUrl.getConnection();
while (!done) {
byte[] part = base64encode(partOfImage);
con.write (part);
partOfImage = nextPartOfImage();
}
con.flush();
con.close();
Also in Android after 2.2 Google recommends the URLConnection over the http client. See the description of DefaultHttpClient.
The other thing you may want to look into is the amount of data to be sent. 10 MB + base64 will take quite a while to transfer (even with gzip compression, which the URLConnection transparently enables if the server side accepts it) over a mobile network.
You must read docs for this REST service, no such service will require you to send such long data in GET. Images are always sent as POST. POST data is always at the end of request and allows to be added iteratively.
I'm using the following code to grab images from the web. It uses Gridview and depending on position, picks a URL from an array. It works but the loading of images is often hit or miss. Almost every time I start the app, a different number of images load.
It also has issues when changing from portrait to landscape view, 5 out of 10 images may be displayed then I'll turn the device and usually lose all the images. Sometimes a few do show up though.
Any ideas on making this more robust?
try {
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
Bitmap bm = BitmapFactory.decodeStream(bis);
bis.close();
return bm;
} catch (IOException e) {
Log.d("DEBUGTAG", "error...");
}
return null;
One thing I read is that there's a known bug with decoding Bitmaps from an InputStream, and the suggested fix from Google was to use a FlushedInputStream (example in below URL):
http://android-developers.blogspot.com/2010/07/multithreading-for-performance.html
Also, I'd put the download code into an AsyncTask. Here's what I currently use for mine:
public static Bitmap loadImageFromUri(URI uri)
{
URL url;
try {
url = uri.toURL();
} catch (MalformedURLException e) {
Log.v("URL Exception", "MalformedURLException");
return null;
}
try
{
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
return BitmapFactory.decodeStream(new FlushedInputStream(input));
}
catch (IOException e)
{
e.printStackTrace();
return null;
}
}
I just pass in a URI due to the way I've got the rest of my code set up, you could pass in a URL instead and skip the first part. This will keep the download from tying up your UI thread.