[LIB-9] Rename chesshog-dbetude module

[chesshog.git] / chesshog-dbetude / src / main / java / org / hedgecode / chess / service / ServiceRegistry.java

diff --git a/chesshog-dbetude/src/main/java/org/hedgecode/chess/service/ServiceRegistry.java b/chesshog-dbetude/src/main/java/org/hedgecode/chess/service/ServiceRegistry.java
new file mode 100644 (file)
index 0000000..a892bb9
--- /dev/null
+++ b/chesshog-dbetude/src/main/java/org/hedgecode/chess/service/ServiceRegistry.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2018. Developed by Hedgecode.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.hedgecode.chess.service;
+
+import java.util.Iterator;
+import java.util.ServiceLoader;
+
+import org.hedgecode.chess.domain.Adapter;
+import org.hedgecode.chess.domain.EtudeAdapter;
+import org.hedgecode.chess.dto.EtudeDTO;
+import org.hedgecode.chess.persistence.PersistenceManager;
+
+/**
+ * Service Provider Interface (SPI) Registry.
+ *
+ * @author Dmitry Samoshin aka gotty
+ */
+public final class ServiceRegistry {
+
+    private ServiceRegistry() {
+    }
+
+    public static <ServiceType> Iterator<ServiceType> providers(Class<ServiceType> serviceClass) {
+        final Iterator<ServiceType> providers = ServiceLoader.load(serviceClass).iterator();
+
+        if (!providers.hasNext()) {
+            throw new ServiceRegistryException("service.provider.not.found", serviceClass.getName());
+        }
+
+        return providers;
+    }
+
+    public static <ServiceType> ServiceType singleProvider(Class<ServiceType> serviceClass) {
+        final Iterator<ServiceType> providers = providers(serviceClass);
+
+        ServiceType provider = providers.next();
+        if (providers.hasNext()) {
+            throw new ServiceRegistryException("service.too.many.providers", serviceClass.getName());
+        }
+
+        return provider;
+    }
+
+    public static <AdapterType extends Adapter, TargetType> AdapterType singleAdapter(
+            Class<AdapterType> adapterClass,
+            Class<TargetType> targetClass)
+    {
+        AdapterType targetAdapter = null;
+
+        final Iterator<AdapterType> providers = providers(adapterClass);
+
+        while (providers.hasNext()) {
+            AdapterType adapter = providers.next();
+            if (adapter.getTargetClass().equals(targetClass)) {
+                if (targetAdapter != null)
+                    throw new ServiceRegistryException(
+                            "service.too.many.adapters", adapterClass.getName(), targetClass.getName()
+                    );
+                targetAdapter = adapter;
+            }
+        }
+        if (targetAdapter == null)
+            throw new ServiceRegistryException(
+                    "service.adapter.not.found", adapterClass.getName(), targetClass.getName()
+            );
+
+        return targetAdapter;
+    }
+
+
+    public static void main(String... args) {
+
+        AuthorService as = ServiceRegistry.singleProvider(AuthorService.class);
+        System.out.println(as);
+        PersistenceManager pm = ServiceRegistry.singleProvider(PersistenceManager.class);
+        System.out.println(pm);
+        EtudeAdapter ea = ServiceRegistry.singleAdapter(EtudeAdapter.class, EtudeDTO.class);
+        System.out.println(ea);
+
+    }
+
+}