Service Tomcat seemingly does not support gradle

In the java web application using "runtime.getruntime.exec ("gradle")" call the server-side gradle implementation of the script, no problem in the use of local procedures, but web procedures deployed tomcat8.5 read errorStream get "java.rmi. Server.exportExpecetion: port already in use: 1099; netsted exception is java.net.bindexception "gradle can not run

No use of the framework, the most basic servlet inside the implementation of the use of java gradle command, (tomcat8.5.7) can not be implemented, for help

servlet code:

 try {
            ProcessBuilder processBuilder = new ProcessBuilder("gradle");
            Process process = processBuilder.start();

            String s=null;
            BufferedReader stdInput = new BufferedReader(new InputStreamReader(process.getInputStream()));
            BufferedReader stdError = new BufferedReader(new InputStreamReader(process.getErrorStream()));
            while ((s = stdInput.readLine()) != null) {
                System.out.println("stdInput"+s);
            }
            while ((s = stdError.readLine()) != null) {
                System.out.println("stdError"+s);
            }
            process.waitFor();

            InputStream inputStream = process.getInputStream();


            byte[] buffer = new byte[2048];
            int readBytes = 0;

            while ((readBytes = inputStream.read(buffer)) > 0) {
                StringBuilder stringBuilder = new StringBuilder();

                stringBuilder.append(new String(buffer, 0, readBytes));
                System.out.println(stringBuilder);

            }
        } catch (Exception e) {
            e.printStackTrace();
        }

I want to use the web to build a apk in gradle commond ,but the Tomcat seemingly does not support gradle