Add utility method for getting Reader contents as String

Needed in future recompilation avoidance for hash calculation.
TODO: Move to a utility class?

Signed-off-by: Squareys <Squareys@googlemail.com>

Author: Squareys

src/main/java/org/scijava/plugins/scripting/java/JavaEngine.java

@@ -46,6 +46,7 @@
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.nio.CharBuffer;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.jar.JarFile;
@@ -755,4 +756,26 @@ private static void getSurefireBooterURLs(final File file, final URL baseURL,
 		}
 	}
 
+	/**
+	 * Read complete contents of a Reader and return as String.
+	 *
+	 * @param reader {@link Reader} whose output should be returned as String.
+	 * @return contents of reader as String.
+	 */
+	private static String getReaderContentsAsString(Reader reader) throws IOException {
+		if (reader == null) {
+			return null;
+		}
+
+		CharBuffer buffer = CharBuffer.allocate(1024);
+		StringBuilder builder = new StringBuilder();
+
+		int read;
+		while ((read = reader.read(buffer)) != -1) {
+			builder.append(buffer, 0, read);
+		}
+
+		return builder.toString();
+	}
+
 }