Include HTTP response body in error messages

build.gradle

@@ -16,8 +16,8 @@ allprojects {
 
 // We compile the library using Java 1.7 compatibility
 // in order to ensure interoperability with older Android platforms.
-sourceCompatibility = 1.8
-targetCompatibility = 1.8
+sourceCompatibility = 1.9
+targetCompatibility = 1.9
 
 // load version number from file
 def config = new ConfigSlurper().parse(new File("${projectDir}/src/main/resources/tus-java-client-version/version.properties").toURI().toURL())

src/main/java/io/tus/java/client/ProtocolException.java

@@ -1,7 +1,9 @@
 package io.tus.java.client;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.HttpURLConnection;
+import java.nio.charset.StandardCharsets;
 
 /**
  * This exception is thrown if the server sends a request with an unexpected status code or
@@ -19,7 +21,7 @@ public ProtocolException(String message) {
     }
 
     /**
-     Instantiates a new Object of type {@link ProtocolException}.
+     * Instantiates a new Object of type {@link ProtocolException}.
      * @param message Message to be thrown with the exception.
      * @param connection {@link HttpURLConnection}, where the error occurred.
      */
@@ -29,7 +31,26 @@ public ProtocolException(String message, HttpURLConnection connection) {
     }
 
     /**
-     * Returns the {@link HttpURLConnection} instances, which caused the error.
+     * Create a new {@link ProtocolException} instance caused by an unexpected status code.
+     * @param connection {@link HttpURLConnection}, where the error occurred.
+     * @param action Description of the action when the error occurred.
+     * @return {@link HttpURLConnection}
+     */
+    static ProtocolException unexpectedStatusCode(HttpURLConnection connection, String action) throws IOException {
+        int code = connection.getResponseCode();
+        String response = "n/a";
+        //System.out.println(connection.getInputStream());
+        InputStream responseStream = connection.getErrorStream();
+        if (responseStream != null) {
+            response = new String(responseStream.readAllBytes(), StandardCharsets.UTF_8).trim();
+        }
+
+        return new ProtocolException(
+                "unexpected status code (" + code + ") while " + action + "; response is: " + response, connection);
+    }
+
+    /**
+     * Returns the {@link HttpURLConnection} instance which caused the error.
      * @return {@link HttpURLConnection}
      */
     public HttpURLConnection getCausingConnection() {

src/main/java/io/tus/java/client/TusClient.java

@@ -208,8 +208,7 @@ public TusUploader createUpload(@NotNull TusUpload upload) throws ProtocolExcept
 
         int responseCode = connection.getResponseCode();
         if (!(responseCode >= 200 && responseCode < 300)) {
-            throw new ProtocolException(
-                    "unexpected status code (" + responseCode + ") while creating upload", connection);
+            throw ProtocolException.unexpectedStatusCode(connection, "creating upload");
         }
 
         String urlStr = connection.getHeaderField("Location");
@@ -303,8 +302,7 @@ public TusUploader beginOrResumeUploadFromURL(@NotNull TusUpload upload, @NotNul
 
         int responseCode = connection.getResponseCode();
         if (!(responseCode >= 200 && responseCode < 300)) {
-            throw new ProtocolException(
-                    "unexpected status code (" + responseCode + ") while resuming upload", connection);
+            throw ProtocolException.unexpectedStatusCode(connection, "resuming upload");
         }
 
         String offsetStr = connection.getHeaderField("Upload-Offset");

src/main/java/io/tus/java/client/TusUploader.java

@@ -337,11 +337,8 @@ private void finishConnection() throws ProtocolException, IOException {
 
         if (connection != null) {
             int responseCode = connection.getResponseCode();
-            connection.disconnect();
-
             if (!(responseCode >= 200 && responseCode < 300)) {
-                throw new ProtocolException("unexpected status code (" + responseCode + ") while uploading chunk",
-                        connection);
+                throw ProtocolException.unexpectedStatusCode(connection, "uploading chunk");
             }
 
             // TODO detect changes and seek accordingly
@@ -358,6 +355,7 @@ private void finishConnection() throws ProtocolException, IOException {
                         connection);
             }
 
+            connection.disconnect();
             connection = null;
         }
     }