How can I get an http response body as a string in Java?

Question

I know there used to be a way to get it with apache commons as documented here: http://hc.apache.org/httpclient-legacy/apidocs/org/apache/commons/httpclient/HttpMethod.html and an example here:

http://www.kodejava.org/examples/416.html

but i believe this is deprecated. Is there any other way to make an http get request in java and get the response body as a string and not a stream?

Answer 1

Every library I can think of returns a stream. You could use IOUtils.toString() from Apache Commons IO to read an InputStream into a String in one method call. E.g.:

URL url = new URL("http://www.example.com/");
URLConnection con = url.openConnection();
InputStream in = con.getInputStream();
String encoding = con.getContentEncoding();
encoding = encoding == null ? "UTF-8" : encoding;
String body = IOUtils.toString(in, encoding);
System.out.println(body);

Update: I changed the example above to use the content encoding from the response if available. Otherwise it'll default to UTF-8 as a best guess, instead of using the local system default.

Answer 2

Here are two examples from my working project.

1. Using EntityUtils and HttpEntity

   HttpResponse response = httpClient.execute(new HttpGet(URL));
   HttpEntity entity = response.getEntity();
   String responseString = EntityUtils.toString(entity, "UTF-8");
   System.out.println(responseString);
   

2. Using BasicResponseHandler

   HttpResponse response = httpClient.execute(new HttpGet(URL));
   String responseString = new BasicResponseHandler().handleResponse(response);
   System.out.println(responseString);
   

Answer 3

Here's an example from another simple project I was working on using the httpclient library from Apache:

String response = new String();
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
nameValuePairs.add(new BasicNameValuePair("j", request));
HttpEntity requestEntity = new UrlEncodedFormEntity(nameValuePairs);

HttpPost httpPost = new HttpPost(mURI);
httpPost.setEntity(requestEntity);
HttpResponse httpResponse = mHttpClient.execute(httpPost);
HttpEntity responseEntity = httpResponse.getEntity();
if(responseEntity!=null) {
    response = EntityUtils.toString(responseEntity);
}

just use EntityUtils to grab the response body as a String. very simple.

Answer 4

This is relatively simple in the specific case, but quite tricky in the general case.

HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet("http://stackoverflow.com/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
System.out.println(EntityUtils.getContentMimeType(entity));
System.out.println(EntityUtils.getContentCharSet(entity));

The answer depends on the Content-Type HTTP response header.

This header contains information about the payload and might define the encoding of textual data. Even if you assume text types, you may need to inspect the content itself in order to determine the correct character encoding. E.g. see the HTML 4 spec for details on how to do that for that particular format.

Once the encoding is known, an InputStreamReader can be used to decode the data.

This answer depends on the server doing the right thing - if you want to handle cases where the response headers don't match the document, or the document declarations don't match the encoding used, that's another kettle of fish.

Answer 5

Below is a simple way of accessing the response as a String using Apache HTTP Client library.

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.BasicResponseHandler;

//... 

HttpGet get;
HttpClient httpClient;

// initialize variables above

ResponseHandler<String> responseHandler = new BasicResponseHandler();
String responseBody = httpClient.execute(get, responseHandler);

Answer 6

How about just this?

org.apache.commons.io.IOUtils.toString(new URL("http://www.someurl.com/"));

Answer 7

The Answer by McDowell is correct one. However if you try other suggestion in few of the posts above.

HttpEntity responseEntity = httpResponse.getEntity();
if(responseEntity!=null) {
   response = EntityUtils.toString(responseEntity);
   S.O.P (response);
}

Then it will give you illegalStateException stating that content is already consumed.

Answer 8

We can use the below code also to get the HTML Response in java

import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.HttpResponse;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import org.apache.log4j.Logger;

public static void main(String[] args) throws Exception {
    HttpClient client = new DefaultHttpClient();
    //  args[0] :-  http://hostname:8080/abc/xyz/CheckResponse
    HttpGet request1 = new HttpGet(args[0]);
    HttpResponse response1 = client.execute(request1);
    int code = response1.getStatusLine().getStatusCode();

    try (BufferedReader br = new BufferedReader(new InputStreamReader((response1.getEntity().getContent())));) {
        // Read in all of the post results into a String.
        String output = "";
        Boolean keepGoing = true;
        while (keepGoing) {
            String currentLine = br.readLine();

            if (currentLine == null) {
                keepGoing = false;
            } else {
                output += currentLine;
            }
        }

        System.out.println("Response-->" + output);
    } catch (Exception e) {
        System.out.println("Exception" + e);

    }
}

Answer 9

Here's a lightweight way to do so:

String responseString = "";
for (int i = 0; i < response.getEntity().getContentLength(); i++) { 
    responseString +=
    Character.toString((char)response.getEntity().getContent().read()); 
}

With of course responseString containing website's response and response being type of HttpResponse, returned by HttpClient.execute(request)

Answer 10

Following is the code snippet which shows better way to handle the response body as a String whether it's a valid response or error response for the HTTP POST request:

BufferedReader reader = null;
OutputStream os = null;
String payload = "";
try {
    URL url1 = new URL("YOUR_URL");
    HttpURLConnection postConnection = (HttpURLConnection) url1.openConnection();
    postConnection.setRequestMethod("POST");
    postConnection.setRequestProperty("Content-Type", "application/json");
    postConnection.setDoOutput(true);
    os = postConnection.getOutputStream();
    os.write(eventContext.getMessage().getPayloadAsString().getBytes());
    os.flush();

    String line;
    try{
        reader = new BufferedReader(new InputStreamReader(postConnection.getInputStream()));
    }
    catch(IOException e){
        if(reader == null)
            reader = new BufferedReader(new InputStreamReader(postConnection.getErrorStream()));
    }
    while ((line = reader.readLine()) != null)
        payload += line.toString();
}       
catch (Exception ex) {
            log.error("Post request Failed with message: " + ex.getMessage(), ex);
} finally {
    try {
        reader.close();
        os.close();
    } catch (IOException e) {
        log.error(e.getMessage(), e);
        return null;
    }
}

Answer 11

You can use a 3-d party library that sends Http request and handles the response. One of the well-known products would be Apache commons HTTPClient: HttpClient javadoc, HttpClient Maven artifact. There is by far less known but much simpler HTTPClient (part of an open source MgntUtils library written by me): MgntUtils HttpClient javadoc, MgntUtils maven artifact, MgntUtils Github. Using either of those libraries you can send your REST request and receive response independently from Spring as part of your business logic

Answer 12

If you are using Jackson to deserialize the response body, one very simple solution is to use request.getResponseBodyAsStream() instead of request.getResponseBodyAsString()