org.springframework.integration.xquery.support.XQueryUtils.java Source code

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Here is the source code for org.springframework.integration.xquery.support.XQueryUtils.java

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/*
 * Copyright 2002-2012 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.xquery.support;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.io.Resource;
import org.springframework.integration.MessagingException;
import org.springframework.util.Assert;

/**
 * The common utility class that is used to perform all common operations
 * amongst XQuery modules. To contain all common operations that would be used
 * by the router, transformer etc along with all the parsers for these components
 *
 * @author Amol Nayak
 *
 * @since 1.0
 *
 */
public final class XQueryUtils {

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

    private XQueryUtils() {
        //prevent instantiation
        throw new AssertionError("Cannot instantiate a utility class");
    }

    /**
     * Reads the XQuery string from the resource file specified
     *
     * @param resource the {@link Resource} instance of the file that contains the XQuery
     *          currently only classpath and file resources are supported
     *
     * @return the XQuery string from the resource specified
     */
    public static String readXQueryFromResource(Resource resource) {
        Assert.notNull(resource, "null resource provided");
        Assert.isTrue(resource.exists(), "Provided XQuery resource does not exist");
        Assert.isTrue(resource.isReadable(), "Provided XQuery resource is not readable");
        BufferedReader reader = null;
        try {
            URL url = resource.getURL();
            InputStream inStream = url.openStream();
            reader = new BufferedReader(new InputStreamReader(inStream));
            String line = reader.readLine();
            StringBuilder builder = new StringBuilder();
            while (line != null) {
                builder.append(line).append("\n");
                line = reader.readLine();
            }
            String xQuery = builder.toString();
            reader.close();
            return xQuery;
        } catch (IOException e) {
            throw new MessagingException("Error while reading the xQuery resource", e);
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    logger.error("Exception while closing reader", e);
                }
            }
        }
    }
}