Java tutorial
/* * Copyright 2015 Open mHealth * * 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.openmhealth.schema.service; import org.openmhealth.schema.domain.omh.SchemaId; import org.openmhealth.schema.domain.omh.SchemaSupport; import org.reflections.Reflections; import org.springframework.stereotype.Service; import javax.annotation.PostConstruct; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Modifier; import java.util.HashSet; import java.util.Set; /** * A schema identifier service that uses reflection at load-time to determine which schema classes are available on the * classpath. * * @author Emerson Farrugia */ @Service public class SchemaClassServiceImpl implements SchemaClassService { public static final String SCHEMA_CLASS_PACKAGE = "org.openmhealth.schema.domain"; private Set<SchemaId> schemaIds = new HashSet<>(); @PostConstruct public void initializeSchemaIds() throws IllegalAccessException, InvocationTargetException, InstantiationException, NoSuchMethodException { Reflections reflections = new Reflections(SCHEMA_CLASS_PACKAGE); for (Class<? extends SchemaSupport> schemaClass : reflections.getSubTypesOf(SchemaSupport.class)) { if (schemaClass.isInterface() || Modifier.isAbstract(schemaClass.getModifiers())) { continue; } SchemaId schemaId; if (schemaClass.isEnum()) { schemaId = schemaClass.getEnumConstants()[0].getSchemaId(); } else { Constructor<? extends SchemaSupport> constructor = schemaClass.getDeclaredConstructor(); constructor.setAccessible(true); schemaId = constructor.newInstance().getSchemaId(); } schemaIds.add(schemaId); } } @Override public Set<SchemaId> getSchemaIds() { return this.schemaIds; } }