Java example source code file (ResourceResolver.java)

This example Java source code file (ResourceResolver.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

attr, class, classnotfoundexception, dom, error, list, object, resolverdirecthttp, resolverlocalfilesystem, resourceresolver, resourceresolvercontext, resourceresolverexception, resourceresolverspi, string, util, xmlsignatureinput

The ResourceResolver.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/**
 * 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 com.sun.org.apache.xml.internal.security.utils.resolver;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;
import com.sun.org.apache.xml.internal.security.utils.resolver.implementations.ResolverDirectHTTP;
import com.sun.org.apache.xml.internal.security.utils.resolver.implementations.ResolverFragment;
import com.sun.org.apache.xml.internal.security.utils.resolver.implementations.ResolverLocalFilesystem;
import com.sun.org.apache.xml.internal.security.utils.resolver.implementations.ResolverXPointer;
import org.w3c.dom.Attr;

/**
 * During reference validation, we have to retrieve resources from somewhere.
 * This is done by retrieving a Resolver. The resolver needs two arguments: The
 * URI in which the link to the new resource is defined and the baseURI of the
 * file/entity in which the URI occurs (the baseURI is the same as the SystemId).
 */
public class ResourceResolver {

    /** {@link org.apache.commons.logging} logging facility */
    private static java.util.logging.Logger log =
        java.util.logging.Logger.getLogger(ResourceResolver.class.getName());

    /** these are the system-wide resolvers */
    private static List<ResourceResolver> resolverList = new ArrayList();

    /** Field resolverSpi */
    private final ResourceResolverSpi resolverSpi;

    /**
     * Constructor ResourceResolver
     *
     * @param resourceResolver
     */
    public ResourceResolver(ResourceResolverSpi resourceResolver) {
        this.resolverSpi = resourceResolver;
    }

    /**
     * Method getInstance
     *
     * @param uri
     * @param baseURI
     * @return the instance
     *
     * @throws ResourceResolverException
     */
    public static final ResourceResolver getInstance(Attr uri, String baseURI)
        throws ResourceResolverException {
        return getInstance(uri, baseURI, false);
    }

    /**
     * Method getInstance
     *
     * @param uri
     * @param baseURI
     * @param secureValidation
     * @return the instance
     *
     * @throws ResourceResolverException
     */
    public static final ResourceResolver getInstance(
        Attr uriAttr, String baseURI, boolean secureValidation
    ) throws ResourceResolverException {
        ResourceResolverContext context = new ResourceResolverContext(uriAttr, baseURI, secureValidation);
        return internalGetInstance(context);
    }

    private static <N> ResourceResolver internalGetInstance(ResourceResolverContext context)
            throws ResourceResolverException {
        synchronized (resolverList) {
            for (ResourceResolver resolver : resolverList) {
                ResourceResolver resolverTmp = resolver;
                if (!resolver.resolverSpi.engineIsThreadSafe()) {
                    try {
                        resolverTmp =
                            new ResourceResolver(resolver.resolverSpi.getClass().newInstance());
                    } catch (InstantiationException e) {
                        throw new ResourceResolverException("", e, context.attr, context.baseUri);
                    } catch (IllegalAccessException e) {
                        throw new ResourceResolverException("", e, context.attr, context.baseUri);
                    }
                }

                if (log.isLoggable(java.util.logging.Level.FINE)) {
                    log.log(java.util.logging.Level.FINE,
                        "check resolvability by class " + resolverTmp.getClass().getName()
                    );
                }

                if ((resolverTmp != null) && resolverTmp.canResolve(context)) {
                    // Check to see whether the Resolver is allowed
                    if (context.secureValidation
                        && (resolverTmp.resolverSpi instanceof ResolverLocalFilesystem
                            || resolverTmp.resolverSpi instanceof ResolverDirectHTTP)) {
                        Object exArgs[] = { resolverTmp.resolverSpi.getClass().getName() };
                        throw new ResourceResolverException(
                            "signature.Reference.ForbiddenResolver", exArgs, context.attr, context.baseUri
                        );
                    }
                    return resolverTmp;
                }
            }
        }

        Object exArgs[] = { ((context.uriToResolve != null)
                ? context.uriToResolve : "null"), context.baseUri };

        throw new ResourceResolverException("utils.resolver.noClass", exArgs, context.attr, context.baseUri);
    }

    /**
     * Method getInstance
     *
     * @param uri
     * @param baseURI
     * @param individualResolvers
     * @return the instance
     *
     * @throws ResourceResolverException
     */
    public static ResourceResolver getInstance(
        Attr uri, String baseURI, List<ResourceResolver> individualResolvers
    ) throws ResourceResolverException {
        return getInstance(uri, baseURI, individualResolvers, false);
    }

    /**
     * Method getInstance
     *
     * @param uri
     * @param baseURI
     * @param individualResolvers
     * @param secureValidation
     * @return the instance
     *
     * @throws ResourceResolverException
     */
    public static ResourceResolver getInstance(
        Attr uri, String baseURI, List<ResourceResolver> individualResolvers, boolean secureValidation
    ) throws ResourceResolverException {
        if (log.isLoggable(java.util.logging.Level.FINE)) {
            log.log(java.util.logging.Level.FINE,
                "I was asked to create a ResourceResolver and got "
                + (individualResolvers == null ? 0 : individualResolvers.size())
            );
        }

        ResourceResolverContext context = new ResourceResolverContext(uri, baseURI, secureValidation);

        // first check the individual Resolvers
        if (individualResolvers != null) {
            for (int i = 0; i < individualResolvers.size(); i++) {
                ResourceResolver resolver = individualResolvers.get(i);

                if (resolver != null) {
                    if (log.isLoggable(java.util.logging.Level.FINE)) {
                        String currentClass = resolver.resolverSpi.getClass().getName();
                        log.log(java.util.logging.Level.FINE, "check resolvability by class " + currentClass);
                    }

                    if (resolver.canResolve(context)) {
                        return resolver;
                    }
                }
            }
        }

        return internalGetInstance(context);
    }

    /**
     * Registers a ResourceResolverSpi class. This method logs a warning if
     * the class cannot be registered.
     *
     * @param className the name of the ResourceResolverSpi class to be registered
     */
    @SuppressWarnings("unchecked")
    public static void register(String className) {
        try {
            Class<ResourceResolverSpi> resourceResolverClass =
                (Class<ResourceResolverSpi>) Class.forName(className);
            register(resourceResolverClass, false);
        } catch (ClassNotFoundException e) {
            log.log(java.util.logging.Level.WARNING, "Error loading resolver " + className + " disabling it");
        }
    }

    /**
     * Registers a ResourceResolverSpi class at the beginning of the provider
     * list. This method logs a warning if the class cannot be registered.
     *
     * @param className the name of the ResourceResolverSpi class to be registered
     */
    @SuppressWarnings("unchecked")
    public static void registerAtStart(String className) {
        try {
            Class<ResourceResolverSpi> resourceResolverClass =
                (Class<ResourceResolverSpi>) Class.forName(className);
            register(resourceResolverClass, true);
        } catch (ClassNotFoundException e) {
            log.log(java.util.logging.Level.WARNING, "Error loading resolver " + className + " disabling it");
        }
    }

    /**
     * Registers a ResourceResolverSpi class. This method logs a warning if the class
     * cannot be registered.
     * @param className
     * @param start
     */
    public static void register(Class<? extends ResourceResolverSpi> className, boolean start) {
        try {
            ResourceResolverSpi resourceResolverSpi = className.newInstance();
            register(resourceResolverSpi, start);
        } catch (IllegalAccessException e) {
            log.log(java.util.logging.Level.WARNING, "Error loading resolver " + className + " disabling it");
        } catch (InstantiationException e) {
            log.log(java.util.logging.Level.WARNING, "Error loading resolver " + className + " disabling it");
        }
    }

    /**
     * Registers a ResourceResolverSpi instance. This method logs a warning if the class
     * cannot be registered.
     * @param resourceResolverSpi
     * @param start
     */
    public static void register(ResourceResolverSpi resourceResolverSpi, boolean start) {
        synchronized(resolverList) {
            if (start) {
                resolverList.add(0, new ResourceResolver(resourceResolverSpi));
            } else {
                resolverList.add(new ResourceResolver(resourceResolverSpi));
            }
        }
        if (log.isLoggable(java.util.logging.Level.FINE)) {
            log.log(java.util.logging.Level.FINE, "Registered resolver: " + resourceResolverSpi.toString());
        }
    }

    /**
     * This method registers the default resolvers.
     */
    public static void registerDefaultResolvers() {
        synchronized(resolverList) {
            resolverList.add(new ResourceResolver(new ResolverFragment()));
            resolverList.add(new ResourceResolver(new ResolverLocalFilesystem()));
            resolverList.add(new ResourceResolver(new ResolverXPointer()));
            resolverList.add(new ResourceResolver(new ResolverDirectHTTP()));
        }
    }

    /**
     * @deprecated New clients should use {@link #resolve(Attr, String, boolean)}
     */
    @Deprecated
    public XMLSignatureInput resolve(Attr uri, String baseURI)
        throws ResourceResolverException {
        return resolve(uri, baseURI, true);
    }

    /**
     * Method resolve
     *
     * @param uri
     * @param baseURI
     * @return the resource
     *
     * @throws ResourceResolverException
     */
    public XMLSignatureInput resolve(Attr uri, String baseURI, boolean secureValidation)
        throws ResourceResolverException {
        ResourceResolverContext context = new ResourceResolverContext(uri, baseURI, secureValidation);
        return resolverSpi.engineResolveURI(context);
    }

    /**
     * Method setProperty
     *
     * @param key
     * @param value
     */
    public void setProperty(String key, String value) {
        resolverSpi.engineSetProperty(key, value);
    }

    /**
     * Method getProperty
     *
     * @param key
     * @return the value of the property
     */
    public String getProperty(String key) {
        return resolverSpi.engineGetProperty(key);
    }

    /**
     * Method addProperties
     *
     * @param properties
     */
    public void addProperties(Map<String, String> properties) {
        resolverSpi.engineAddProperies(properties);
    }

    /**
     * Method getPropertyKeys
     *
     * @return all property keys.
     */
    public String[] getPropertyKeys() {
        return resolverSpi.engineGetPropertyKeys();
    }

    /**
     * Method understandsProperty
     *
     * @param propertyToTest
     * @return true if the resolver understands the property
     */
    public boolean understandsProperty(String propertyToTest) {
        return resolverSpi.understandsProperty(propertyToTest);
    }

    /**
     * Method canResolve
     *
     * @param uri
     * @param baseURI
     * @return true if it can resolve the uri
     */
    private boolean canResolve(ResourceResolverContext context) {
        return this.resolverSpi.engineCanResolveURI(context);
    }
}