001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.component;
018    
019    import java.io.ByteArrayInputStream;
020    import java.io.IOException;
021    import java.io.InputStream;
022    
023    import org.apache.camel.Component;
024    import org.apache.camel.api.management.ManagedAttribute;
025    import org.apache.camel.api.management.ManagedOperation;
026    import org.apache.camel.api.management.ManagedResource;
027    import org.apache.camel.api.management.mbean.ManagedResourceEndpointMBean;
028    import org.apache.camel.converter.IOConverter;
029    import org.apache.camel.impl.ProcessorEndpoint;
030    import org.apache.camel.util.IOHelper;
031    import org.apache.camel.util.ResourceHelper;
032    import org.slf4j.Logger;
033    import org.slf4j.LoggerFactory;
034    
035    /**
036     * A useful base class for endpoints which depend on a resource
037     * such as things like Velocity or XQuery based components.
038     */
039    @ManagedResource(description = "Managed ResourceEndpoint")
040    public abstract class ResourceEndpoint extends ProcessorEndpoint implements ManagedResourceEndpointMBean {
041        protected final transient Logger log = LoggerFactory.getLogger(getClass());
042        private String resourceUri;
043        private boolean contentCache;
044        private volatile byte[] buffer;
045    
046        public ResourceEndpoint() {
047        }
048    
049        public ResourceEndpoint(String endpointUri, Component component, String resourceUri) {
050            super(endpointUri, component);
051            this.resourceUri = resourceUri;
052        }
053    
054        /**
055         * Gets the resource as an input stream considering the cache flag as well.
056         * <p/>
057         * If cache is enabled then the resource content is cached in an internal buffer and this content is
058         * returned to avoid loading the resource over and over again.
059         *
060         * @return the input stream
061         * @throws IOException is thrown if error loading the content of the resource to the local cache buffer
062         */
063        public InputStream getResourceAsInputStream() throws IOException {
064            // try to get the resource input stream
065            InputStream is;
066            if (isContentCache()) {
067                synchronized (this) {
068                    if (buffer == null) {
069                        log.debug("Reading resource: {} into the content cache", resourceUri);
070                        is = getResourceAsInputStreamWithoutCache();
071                        buffer = IOConverter.toBytes(is);
072                        IOHelper.close(is, resourceUri, log);
073                    }
074                }
075                log.debug("Using resource: {} from the content cache", resourceUri);
076                return new ByteArrayInputStream(buffer);
077            }
078    
079            return getResourceAsInputStreamWithoutCache();
080        }
081    
082        protected InputStream getResourceAsInputStreamWithoutCache() throws IOException {
083            return loadResource(resourceUri);
084        }
085    
086        /**
087         * Loads the given resource.
088         *
089         * @param uri uri of the resource.
090         * @return the loaded resource
091         * @throws IOException is thrown if resource is not found or cannot be loaded
092         */
093        protected InputStream loadResource(String uri) throws IOException {
094            return ResourceHelper.resolveMandatoryResourceAsInputStream(getCamelContext().getClassResolver(), uri);
095        }
096    
097        @ManagedAttribute(description = "Whether the resource is cached")
098        public boolean isContentCache() {
099            return contentCache;
100        }
101    
102        @ManagedOperation(description = "Clears the cached resource, forcing to re-load the resource on next request")
103        public void clearContentCache() {
104            log.debug("Clearing resource: {} from the content cache", resourceUri);
105            buffer = null;
106        }
107    
108        public boolean isContentCacheCleared() {
109            return buffer == null;
110        }
111    
112        /**
113         * Sets whether to use resource content cache or not - default is <tt>false</tt>.
114         *
115         * @see #getResourceAsInputStream()
116         */
117        public void setContentCache(boolean contentCache) {
118            this.contentCache = contentCache;
119        }
120    
121        public String getResourceUri() {
122            return resourceUri;
123        }
124    
125        public void setResourceUri(String resourceUri) {
126            this.resourceUri = resourceUri;
127        }
128    }