Get the content from a HttpResponse (or any InputStream) as a String

6 votes · 6 comments

This snippet reads all of the InputStream into a String. Useful for any kind of InputStream, including the content of a HttpResponse after a HttpClient request. See also this answer on SO. Essentially StringBuilder is a lot faster, and can be converted to a normal String with the .toString() method.

For reading the content of a HttpResponse use inputStreamToString(response.getEntity().getContent()).

raw · 
copy
 · download// Fast Implementation
private StringBuilder inputStreamToString(InputStream is) {
    String line = "";
    StringBuilder total = new StringBuilder();
    
    // Wrap a BufferedReader around the InputStream
    BufferedReader rd = new BufferedReader(new InputStreamReader(is));

    // Read response until the end
    while ((line = rd.readLine()) != null) { 
        total.append(line); 
    }
    
    // Return full string
    return total;
}

// Slow Implementation
private String inputStreamToString(InputStream is) {
    String s = "";
    String line = "";
    
    // Wrap a BufferedReader around the InputStream
    BufferedReader rd = new BufferedReader(new InputStreamReader(is));
    
    // Read response until the end
    while ((line = rd.readLine()) != null) { s += line; }
    
    // Return full string
    return s;
}

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6 Comments

ulrich.scheller

You can also use the EasyHttpClient for downloading Web-URLs as a String.

EasyHttpClient client = new EasyHttpClient();
System.out.println(client.get("https://encrypted.google.com/"));

Reply · April 5, 2011, 11:48 a.m.

axx3andspace

EasyHttpClient must be a 3rd-party lib? It's not being recognized via a simple copy-and-paste...

Reply · May 1, 2014, 9:11 p.m.

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Reply · March 19, 2012, 11:52 a.m.

app.minf

Actually, you have a very very minor issue in this solution. Your read 'line' is outside the loop.

String is immutable. As we all know. In any case, you wont be reading anything larger that 128K in this kind of solution. (This is still the maximum size of a String, right?...or is it larger now?). But just because (and only 'just because') String is immutable, you might want to do the following just to allow a bit of garbage collection within the loop (although it really doesn't matter) And who knows, GC may never occur within this time anyway:

rd = new BufferedReader(new InputStreamReader(is));

while (true) {
    String line = rd.readLine();
    if (line == null)
        break;
    sb.append(line);
}

Enjoy.

Reply · March 21, 2014, 6:39 a.m.

app.minf

Oh...and if you want to retain your line endings, be sure to do

sb.append(line).append("\n");

Don't forget!

Reply · March 21, 2014, 6:40 a.m.

app.minf

Re: String length...sorry, I was thinking of something else. Perhaps there is only an MAX_INT limit.

So if you are going to read a 200MB text file with this loop, you really might want to consider allow some GC.

Reply · March 21, 2014, 6:49 a.m.