Read error response body in Java

Dan_Fabulich_54829 0
Viewed 90551

In Java, this code throws an exception when the HTTP result is 404 range:

URL url = new URL("http://stackoverflow.com/asdf404notfound");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.getInputStream(); // throws!

In my case, I happen to know that the content is 404, but I'd still like to read the body of the response anyway.

(In my actual case the response code is 403, but the body of the response explains the reason for rejection, and I'd like to display that to the user.)

How can I access the response body?

httpurlconnection http java
8 Answers

Here is the bug report (close, will not fix, not a bug).

Their advice there is to code like this:

HttpURLConnection httpConn = (HttpURLConnection)_urlConnection;
InputStream _is;
if (httpConn.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
    _is = httpConn.getInputStream();
} else {
     /* error from server */
    _is = httpConn.getErrorStream();
}
TofuBeer_658680

I know that this doesn't answer the question directly, but instead of using the HTTP connection library provided by Sun, you might want to take a look at Commons HttpClient, which (in my opinion) has a far easier API to work with.

user_42490

First check the response code and then use HttpURLConnection.getErrorStream()

user_147830 
InputStream is = null;
if (httpConn.getResponseCode() !=200) {
    is = httpConn.getErrorStream();
} else {
     /* error from server */
    is = httpConn.getInputStream();
}
Admin1

My running code.

  HttpURLConnection httpConn = (HttpURLConnection) urlConn;    
 if (httpConn.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
                        in = new InputStreamReader(urlConn.getInputStream());
                        BufferedReader bufferedReader = new BufferedReader(in);
                        if (bufferedReader != null) {
                            int cp;
                            while ((cp = bufferedReader.read()) != -1) {
                                sb.append((char) cp);
                            }
                            bufferedReader.close();
                        }
                            in.close();

                    } else {
                        /* error from server */
                        in = new InputStreamReader(httpConn.getErrorStream());
                    BufferedReader bufferedReader = new BufferedReader(in);
                    if (bufferedReader != null) {
                        int cp;
                        while ((cp = bufferedReader.read()) != -1) {
                            sb.append((char) cp);
                        }
                        bufferedReader.close();
                    }    
                    in.close();
                    }
                    System.out.println("sb="+sb);
user_15059690

How to read 404 response body in java:

Use Apache library - https://hc.apache.org/httpcomponents-client-4.5.x/httpclient/apidocs/

or Java 11 - https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html

Snippet given below uses Apache:

import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.util.EntityUtils;

CloseableHttpClient client = HttpClients.createDefault();
CloseableHttpResponse resp = client.execute(new HttpGet(domainName + "/blablablabla.html"));
String response = EntityUtils.toString(resp.getEntity());
user_51354930
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