Java tutorial
/* * $Id: ClasspathConfigurationProvider.java 501717 2007-01-31 03:51:11Z mrdon $ * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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.apache.struts2.config; import java.lang.annotation.Annotation; import java.lang.reflect.Modifier; import java.net.URL; import java.util.HashMap; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.opensymphony.xwork2.Action; import com.opensymphony.xwork2.config.Configuration; import com.opensymphony.xwork2.config.ConfigurationException; import com.opensymphony.xwork2.config.ConfigurationProvider; import com.opensymphony.xwork2.config.entities.ActionConfig; import com.opensymphony.xwork2.config.entities.PackageConfig; import com.opensymphony.xwork2.config.entities.ResultConfig; import com.opensymphony.xwork2.config.entities.ResultTypeConfig; import com.opensymphony.xwork2.inject.ContainerBuilder; import com.opensymphony.xwork2.inject.Inject; import com.opensymphony.xwork2.util.ClassLoaderUtil; import com.opensymphony.xwork2.util.ResolverUtil; import com.opensymphony.xwork2.util.TextUtils; import com.opensymphony.xwork2.util.ResolverUtil.Test; import com.opensymphony.xwork2.util.location.LocatableProperties; /** * ClasspathConfigurationProvider loads the configuration * by scanning the classpath or selected packages for Action classes. * <p> * This provider is only invoked if one or more action packages are passed to the dispatcher, * usually from the web.xml. * Configurations are created for objects that either implement Action or have classnames that end with "Action". */ public class ClasspathConfigurationProvider implements ConfigurationProvider { /** * The default page prefix (or "path"). * Some applications may place pages under "/WEB-INF" as an extreme security precaution. */ private static final String DEFAULT_PAGE_PREFIX = "struts.configuration.classpath.defaultPagePrefix"; /** * The default page prefix (none). */ private String defaultPagePrefix = ""; /** * The default page extension, to use in place of ".jsp". */ private static final String DEFAULT_PAGE_EXTENSION = "struts.configuration.classpath.defaultPageExtension"; /** * The defacto default page extension, usually associated with JavaServer Pages. */ private String defaultPageExtension = ".jsp"; /** * A setting to indicate a custom default parent package, * to use in place of "struts-default". */ private static final String DEFAULT_PARENT_PACKAGE = "struts.configuration.classpath.defaultParentPackage"; /** * Name of the framework's default configuration package, * that application configuration packages automatically inherit. */ private String defaultParentPackage = "struts-default"; /** * The default page prefix (or "path"). * Some applications may place pages under "/WEB-INF" as an extreme security precaution. */ private static final String FORCE_LOWER_CASE = "struts.configuration.classpath.forceLowerCase"; /** * Whether to use a lowercase letter as the initial letter of an action. * If false, actions will retain the initial uppercase letter from the Action class. * (<code>view.action</code> (true) versus <code>View.action</code> (false)). */ private boolean forceLowerCase = true; /** * Default suffix that can be used to indicate POJO "Action" classes. */ private static final String ACTION = "Action"; /** * Helper class to scan class path for server pages. */ private PageLocator pageLocator = new ClasspathPageLocator(); /** * Flag to indicate the packages have been loaded. * * @see #loadPackages * @see #needsReload */ private boolean initialized = false; /** * The list of packages to scan for Action classes. */ private String[] packages; /** * The package configurations for scanned Actions. * * @see #loadPackageConfig */ private Map<String, PackageConfig> loadedPackageConfigs = new HashMap<String, PackageConfig>(); /** * Logging instance for this class. */ private static final Log LOG = LogFactory.getLog(ClasspathConfigurationProvider.class); /** * The XWork Configuration for this application. * * @see #init */ private Configuration configuration; /** * Create instance utilizing a list of packages to scan for Action classes. * * @param pkgs List of pacaktges to scan for Action Classes. */ public ClasspathConfigurationProvider(String[] pkgs) { this.packages = pkgs; } /** * PageLocator defines a locate method that can be used to discover server pages. */ public static interface PageLocator { public URL locate(String path); } /** * ClasspathPathLocator searches the classpath for server pages. */ public static class ClasspathPageLocator implements PageLocator { public URL locate(String path) { return ClassLoaderUtil.getResource(path, getClass()); } } /** * Register a default parent package for the actions. * * @param defaultParentPackage the new defaultParentPackage */ @Inject(value = DEFAULT_PARENT_PACKAGE, required = false) public void setDefaultParentPackage(String defaultParentPackage) { this.defaultParentPackage = defaultParentPackage; } /** * Register a default page extension to use when locating pages. * * @param defaultPageExtension the new defaultPageExtension */ @Inject(value = DEFAULT_PAGE_EXTENSION, required = false) public void setDefaultPageExtension(String defaultPageExtension) { this.defaultPageExtension = defaultPageExtension; } /** * Reigster a default page prefix to use when locating pages. * * @param defaultPagePrefix the defaultPagePrefix to set */ @Inject(value = DEFAULT_PAGE_PREFIX, required = false) public void setDefaultPagePrefix(String defaultPagePrefix) { this.defaultPagePrefix = defaultPagePrefix; } /** * Whether to use a lowercase letter as the initial letter of an action. * * @param force If false, actions will retain the initial uppercase letter from the Action class. * (<code>view.action</code> (true) versus <code>View.action</code> (false)). */ @Inject(value = FORCE_LOWER_CASE, required = false) public void setForceLowerCase(String force) { this.forceLowerCase = "true".equals(force); } /** * Register a PageLocation to use to scan for server pages. * * @param locator */ public void setPageLocator(PageLocator locator) { this.pageLocator = locator; } /** * Scan a list of packages for Action classes. * * This method loads classes that implement the Action interface * or have a class name that ends with the letters "Action". * * @param pkgs A list of packages to load * @see #processActionClass */ protected void loadPackages(String[] pkgs) { ResolverUtil<Class> resolver = new ResolverUtil<Class>(); resolver.find(new Test() { // Match Action implementations and classes ending with "Action" public boolean matches(Class type) { // TODO: should also find annotated classes return (Action.class.isAssignableFrom(type) || type.getSimpleName().endsWith("Action")); } }, pkgs); Set<? extends Class<? extends Class>> actionClasses = resolver.getClasses(); for (Object obj : actionClasses) { Class cls = (Class) obj; if (!Modifier.isAbstract(cls.getModifiers())) { processActionClass(cls, pkgs); } } for (String key : loadedPackageConfigs.keySet()) { configuration.addPackageConfig(key, loadedPackageConfigs.get(key)); } } /** * Create a default action mapping for a class instance. * * The namespace annotation is honored, if found, otherwise * the Java package is converted into the namespace * by changing the dots (".") to slashes ("/"). * * @param cls Action or POJO instance to process * @param pkgs List of packages that were scanned for Actions */ protected void processActionClass(Class cls, String[] pkgs) { String name = cls.getName(); String actionPackage = cls.getPackage().getName(); String actionNamespace = null; String actionName = null; for (String pkg : pkgs) { if (name.startsWith(pkg)) { if (LOG.isDebugEnabled()) { LOG.debug("ClasspathConfigurationProvider: Processing class " + name); } name = name.substring(pkg.length() + 1); actionNamespace = ""; actionName = name; int pos = name.lastIndexOf('.'); if (pos > -1) { actionNamespace = "/" + name.substring(0, pos).replace('.', '/'); actionName = name.substring(pos + 1); } break; } } PackageConfig pkgConfig = loadPackageConfig(actionNamespace, actionPackage, cls); // In case the package changed due to namespace annotation processing if (!actionPackage.equals(pkgConfig.getName())) { actionPackage = pkgConfig.getName(); } Annotation annotation = cls.getAnnotation(ParentPackage.class); if (annotation != null) { String parent = ((ParentPackage) annotation).value(); PackageConfig parentPkg = configuration.getPackageConfig(parent); if (parentPkg == null) { throw new ConfigurationException( "ClasspathConfigurationProvider: Unable to locate parent package " + parent, annotation); } pkgConfig.addParent(parentPkg); if (!TextUtils.stringSet(pkgConfig.getNamespace()) && TextUtils.stringSet(parentPkg.getNamespace())) { pkgConfig.setNamespace(parentPkg.getNamespace()); } } // Truncate Action suffix if found if (actionName.endsWith(ACTION)) { actionName = actionName.substring(0, actionName.length() - ACTION.length()); } // Force initial letter of action to lowercase, if desired if ((forceLowerCase) && (actionName.length() > 1)) { int lowerPos = actionName.lastIndexOf('/') + 1; StringBuilder sb = new StringBuilder(); sb.append(actionName.substring(0, lowerPos)); sb.append(Character.toLowerCase(actionName.charAt(lowerPos))); sb.append(actionName.substring(lowerPos + 1)); actionName = sb.toString(); } ActionConfig actionConfig = new ActionConfig(); actionConfig.setClassName(cls.getName()); actionConfig.setPackageName(actionPackage); actionConfig.setResults(new ResultMap<String, ResultConfig>(cls, actionName, pkgConfig)); pkgConfig.addActionConfig(actionName, actionConfig); } /** * Finds or creates the package configuration for an Action class. * * The namespace annotation is honored, if found, * and the namespace is checked for a parent configuration. * * @param actionNamespace The configuration namespace * @param actionPackage The Java package containing our Action classes * @param actionClass The Action class instance * @return PackageConfig object for the Action class */ protected PackageConfig loadPackageConfig(String actionNamespace, String actionPackage, Class actionClass) { PackageConfig parent = null; if (actionClass != null) { Namespace ns = (Namespace) actionClass.getAnnotation(Namespace.class); if (ns != null) { parent = loadPackageConfig(actionNamespace, actionPackage, null); actionNamespace = ns.value(); actionPackage = actionClass.getName(); } } PackageConfig pkgConfig = loadedPackageConfigs.get(actionPackage); if (pkgConfig == null) { pkgConfig = new PackageConfig(); pkgConfig.setName(actionPackage); if (parent == null) { parent = configuration.getPackageConfig(defaultParentPackage); } if (parent == null) { throw new ConfigurationException( "ClasspathConfigurationProvider: Unable to locate default parent package: " + defaultParentPackage); } pkgConfig.addParent(parent); pkgConfig.setNamespace(actionNamespace); loadedPackageConfigs.put(actionPackage, pkgConfig); } return pkgConfig; } /** * Default destructor. Override to provide behavior. */ public void destroy() { } /** * Register this application's configuration. * * @param config The configuration for this application. */ public void init(Configuration config) { this.configuration = config; } /** * Clears and loads the list of packages registered at construction. * * @throws ConfigurationException */ public void loadPackages() throws ConfigurationException { loadedPackageConfigs.clear(); loadPackages(packages); initialized = true; } /** * Indicates whether the packages have been initialized. * * @return True if the packages have been initialized */ public boolean needsReload() { return !initialized; } /** * Creates ResultConfig objects from result annotations, * and if a result isn't found, creates it on the fly. */ class ResultMap<K, V> extends HashMap<K, V> { private Class actionClass; private String actionName; private PackageConfig pkgConfig; public ResultMap(Class actionClass, String actionName, PackageConfig pkgConfig) { this.actionClass = actionClass; this.actionName = actionName; this.pkgConfig = pkgConfig; // check if any annotations are around while (!actionClass.getName().equals(Object.class.getName())) { //noinspection unchecked Results results = (Results) actionClass.getAnnotation(Results.class); if (results != null) { // first check here... for (int i = 0; i < results.value().length; i++) { Result result = results.value()[i]; ResultConfig config = createResultConfig(result); put((K) config.getName(), (V) config); } } // what about a single Result annotation? Result result = (Result) actionClass.getAnnotation(Result.class); if (result != null) { ResultConfig config = createResultConfig(result); put((K) config.getName(), (V) config); } actionClass = actionClass.getSuperclass(); } } /** * Extracts result name and value and calls {@link #createResultConfig}. * * @param result Result annotation reference representing result type to create * @return New or cached ResultConfig object for result */ protected ResultConfig createResultConfig(Result result) { Class<? extends Object> cls = result.type(); if (cls == NullResult.class) { cls = null; } return createResultConfig(result.name(), cls, result.value(), createParameterMap(result.params())); } protected Map<String, String> createParameterMap(String[] parms) { Map<String, String> map = new HashMap<String, String>(); int subtract = parms.length % 2; if (subtract != 0) { LOG.warn("Odd number of result parameters key/values specified. The final one will be ignored."); } for (int i = 0; i < parms.length - subtract; i++) { String key = parms[i++]; String value = parms[i]; map.put(key, value); if (LOG.isDebugEnabled()) { LOG.debug("Adding parmeter[" + key + ":" + value + "] to result."); } } return map; } /** * Creates a default ResultConfig, * using either the resultClass or the default ResultType for configuration package * associated this ResultMap class. * * @param key The result type name * @param resultClass The class for the result type * @param location Path to the resource represented by this type * @return A ResultConfig for key mapped to location */ private ResultConfig createResultConfig(Object key, Class<? extends Object> resultClass, String location, Map<? extends Object, ? extends Object> configParams) { if (resultClass == null) { String defaultResultType = pkgConfig.getFullDefaultResultType(); ResultTypeConfig resultType = pkgConfig.getAllResultTypeConfigs().get(defaultResultType); configParams = resultType.getParams(); String className = resultType.getClazz(); try { resultClass = ClassLoaderUtil.loadClass(className, getClass()); } catch (ClassNotFoundException ex) { throw new ConfigurationException( "ClasspathConfigurationProvider: Unable to locate result class " + className, actionClass); } } String defaultParam; try { defaultParam = (String) resultClass.getField("DEFAULT_PARAM").get(null); } catch (Exception e) { // not sure why this happened, but let's just use a sensible choice defaultParam = "location"; } HashMap params = new HashMap(); if (configParams != null) { params.putAll(configParams); } params.put(defaultParam, location); return new ResultConfig((String) key, resultClass.getName(), params); } } // See superclass for Javadoc public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { // Override to provide functionality } }