Java tutorial
/* * Copyright (C) 2015 Strand Life Sciences. * * 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 com.strandls.alchemy.rest.client; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.util.ArrayList; import java.util.Arrays; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import java.util.Set; import javax.inject.Singleton; import javax.ws.rs.Consumes; import javax.ws.rs.DELETE; import javax.ws.rs.GET; import javax.ws.rs.HttpMethod; import javax.ws.rs.POST; import javax.ws.rs.PUT; import javax.ws.rs.Path; import javax.ws.rs.Produces; import org.apache.commons.lang3.StringUtils; import org.reflections.ReflectionUtils; import com.google.common.base.Predicate; import com.google.common.cache.CacheBuilder; import com.google.common.cache.CacheLoader; import com.google.common.cache.LoadingCache; /** * Analyzes {@link Class} to extract {@link RestInterfaceMetadata}. * * @author Ashish Shinde * */ @Singleton public class RestInterfaceAnalyzer { /** * The cache from class to rest metadata. */ private final LoadingCache<Class<?>, RestInterfaceMetadata> metadataCache; /** * Creates a new instance. */ public RestInterfaceAnalyzer() { metadataCache = CacheBuilder.newBuilder().build(new CacheLoader<Class<?>, RestInterfaceMetadata>() { @Override public RestInterfaceMetadata load(final Class<?> klass) throws Exception { return doAnalyze(klass); } }); } /** * Analyze the class and build the meta information. * * @param klass * the class. * @return analyzed metadata. */ public RestInterfaceMetadata analyze(final Class<?> klass) throws NotRestInterfaceException { try { return metadataCache.getUnchecked(klass); } catch (final Exception e) { final Throwable cause = e.getCause(); if (cause != null && cause instanceof NotRestInterfaceException) { throw (NotRestInterfaceException) cause; } throw e; } } /** * Get rest meta data for the method. * * @param method * the method to analyze. * @return the metadata for a method. */ private RestMethodMetadata analyzeMethod(final Method method) { String path = ""; String httpMethod = null; final List<String> produced = new ArrayList<String>(); final List<String> consumed = new ArrayList<String>(); final Annotation[] annotations = method.getDeclaredAnnotations(); for (final Annotation annotation : annotations) { if (annotation instanceof Path) { path = ((Path) annotation).value(); } else if (annotation instanceof GET) { httpMethod = HttpMethod.GET; } else if (annotation instanceof PUT) { httpMethod = HttpMethod.PUT; } else if (annotation instanceof POST) { httpMethod = HttpMethod.POST; } else if (annotation instanceof DELETE) { httpMethod = HttpMethod.DELETE; } else if (annotation instanceof Produces) { final Produces produces = (Produces) annotation; produced.addAll(Arrays.asList(produces.value())); } else if (annotation instanceof Consumes) { final Consumes consumes = (Consumes) annotation; consumed.addAll(Arrays.asList(consumes.value())); } } if (StringUtils.isBlank(httpMethod)) { // no http method specified. return null; } return new RestMethodMetadata(path, httpMethod, produced, consumed, method.getParameterAnnotations()); } /** * Analyze the class and build the meta information. * * @param klass * the class. * @return analyzed metadata. * @throws NotRestInterfaceException * if the class analyzed is not a rest interface. */ protected RestInterfaceMetadata doAnalyze(final Class<?> klass) throws NotRestInterfaceException { final List<String> produced = new ArrayList<String>(); final List<String> consumed = new ArrayList<String>(); String path = null; @SuppressWarnings("unchecked") final Set<Annotation> declaredAnnotationList = ReflectionUtils.getAllAnnotations(klass); for (final Annotation annotation : declaredAnnotationList) { if (annotation instanceof Path) { path = ((Path) annotation).value(); } else if (annotation instanceof Produces) { final Produces produces = (Produces) annotation; final String[] values = produces.value(); produced.addAll(Arrays.asList(values)); } else if (annotation instanceof Consumes) { final Consumes consumes = (Consumes) annotation; final String[] values = consumes.value(); consumed.addAll(Arrays.asList(values)); } } final Map<Method, RestMethodMetadata> methodMetadataMap = new LinkedHashMap<Method, RestMethodMetadata>(); @SuppressWarnings("unchecked") final Set<Method> methods = ReflectionUtils.getAllMethods(klass, new Predicate<Method>() { @Override public boolean apply(final Method input) { // return only public methods return Modifier.isPublic(input.getModifiers()); } }); for (final Method method : methods) { final RestMethodMetadata methodMetadata = analyzeMethod(method); if (methodMetadata != null) { methodMetadataMap.put(method, methodMetadata); } } if (methodMetadataMap.isEmpty()) { // not a valid rest interface. throw new NotRestInterfaceException(klass); } return new RestInterfaceMetadata(path, produced, consumed, methodMetadataMap); } }