Is this JAX-WS client call thread safe?

Question

Since initialization of the WS client service and port takes ages I like to initialize them once at startup and reuse the same instance of the port. Initalization would look

Answer 1

A general solution for this is to use multiple client objects in a pool, then to use proxy that acts as a facade.

import org.apache.commons.pool2.BasePooledObjectFactory;
import org.apache.commons.pool2.PooledObject;
import org.apache.commons.pool2.impl.DefaultPooledObject;
import org.apache.commons.pool2.impl.GenericObjectPool;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

class ServiceObjectPool extends GenericObjectPool {
        public ServiceObjectPool(java.util.function.Supplier factory) {
            super(new BasePooledObjectFactory() {
                @Override
                public T create() throws Exception {
                    return factory.get();
                }
            @Override
            public PooledObject wrap(T obj) {
                return new DefaultPooledObject<>(obj);
            }
        });
    }

    public static class PooledServiceProxy implements InvocationHandler {
        private ServiceObjectPool pool;

        public PooledServiceProxy(ServiceObjectPool pool) {
            this.pool = pool;
        }


        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            T t = null;
            try {
                t = this.pool.borrowObject();
                return method.invoke(t, args);
            } finally {
                if (t != null)
                    this.pool.returnObject(t);
            }
        }
    }

    @SuppressWarnings("unchecked")
    public T getProxy(Class interfaceType) {
        PooledServiceProxy handler = new PooledServiceProxy<>(this);
        return (T) Proxy.newProxyInstance(interfaceType.getClassLoader(),
                                          new Class[]{interfaceType}, handler);
    }
}

To use the proxy:

ServiceObjectPool servicePool = new ServiceObjectPool<>(createSomeNonThreadSafeService);
nowSafeService = servicePool .getProxy(SomeNonThreadSafeService.class);