org.springframework.integration.aws.s3.DefaultFileNameGenerationStrategy.java Source code

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Here is the source code for org.springframework.integration.aws.s3.DefaultFileNameGenerationStrategy.java

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/*
 * Copyright 2002-2013 the original author or authors.
 *
 * 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.springframework.integration.aws.s3;

import java.io.File;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.integration.Message;
import org.springframework.integration.util.AbstractExpressionEvaluator;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * The Default file name generation strategy. The strategy does the below steps for file name
 * generation
 * 1. The expression provided for generation of the file name, it is evaluated and
 * if a value is obtained, it is used. By default it used the value present in the
 * file_name header.
 * 2. Else, if the provided payload is of type {@link File}, then the name of the file is used.
 * if the file name ends with the temporary file suffix, the suffix is removed and the
 * remainder of the file is used as the name.
 * 3. If none of the above two are provided, the file name is the <Message Id>.ext
 *
 * @author Amol Nayak
 *
 * @since 0.5
 *
 */
public class DefaultFileNameGenerationStrategy extends AbstractExpressionEvaluator
        implements FileNameGenerationStrategy {

    private final Log logger = LogFactory.getLog(DefaultFileNameGenerationStrategy.class);

    private volatile String temporarySuffix = ".writing";

    private volatile String fileNameExpression = "headers['" + AmazonS3MessageHeaders.FILE_NAME + "']";

    /* (non-Javadoc)
     * @see org.springframework.integration.aws.s3.FileNameGenerationStrategy#generateFileName(org.springframework.integration.Message)
     */
    public String generateFileName(Message<?> message) {
        String generatedFileName;
        try {
            String fileName = evaluateExpression(fileNameExpression, message, String.class);
            if (StringUtils.hasText(fileName)) {
                return fileName;
            }
        } catch (Exception e) {
            //Some exception while evaluating using expression, continue to the file Name
            //Ignore
            logger.warn("Exception while evaluating the expression '" + fileNameExpression + "' on the message", e);
        }
        Object payload = message.getPayload();
        if (payload instanceof File) {
            String fileName = ((File) payload).getName();
            if (fileName.endsWith(temporarySuffix)) {
                //chop off the temp suffix
                generatedFileName = fileName.substring(0, fileName.indexOf(temporarySuffix));
            } else {
                generatedFileName = fileName;
            }
        } else {
            //use the default name generated
            generatedFileName = message.getHeaders().getId() + ".ext";
        }
        if (logger.isInfoEnabled()) {
            logger.info("Generated file name is " + generatedFileName);
        }

        return generatedFileName;

    }

    public void setTemporarySuffix(String temporarySuffix) {
        Assert.hasText(temporarySuffix, "Temporary directory suffix should be non null, non empty");
        this.temporarySuffix = temporarySuffix;
    }

    public void setFileNameExpression(String fileNameExpression) {
        Assert.hasText(fileNameExpression,
                "Remote name generation expression should be non null, non empty string");
        this.fileNameExpression = fileNameExpression;
    }
}