org.ngrinder.common.util.FileUtil.java Source code

Introduction

Here is the source code for org.ngrinder.common.util.FileUtil.java

Source

/* 
 * 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.ngrinder.common.util;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.channels.FileLock;

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * File utilities.
 * 
 * @author JunHo Yoon
 * @since 3.1
 */
public abstract class FileUtil {
    private static final Logger LOGGER = LoggerFactory.getLogger(FileUtil.class);

    /**
     * Write object into file.
     * 
     * @param file
     *            file
     * @param obj
     *            obj to be written.
     */
    public static void writeObjectToFile(File file, Object obj) {
        FileOutputStream fout = null;
        ObjectOutputStream oout = null;
        ByteArrayOutputStream bout = null;
        FileLock lock = null;
        try {
            bout = new ByteArrayOutputStream();
            oout = new ObjectOutputStream(bout);
            oout.writeObject(obj);
            oout.flush();
            byte[] byteArray = bout.toByteArray();
            fout = new FileOutputStream(file, false);
            lock = fout.getChannel().lock();
            fout.write(byteArray);
        } catch (Exception e) {
            LOGGER.error("IO error for file {} : {}", file, e.getMessage());
            LOGGER.debug("Details : ", e);
        } finally {
            if (lock != null) {
                try {
                    lock.release();
                } catch (Exception e) {
                    LOGGER.error("unlocking is failed for file {}", file, e);
                }
            }
            IOUtils.closeQuietly(bout);
            IOUtils.closeQuietly(fout);
            IOUtils.closeQuietly(oout);
        }
    }

    /**
     * Read object from file.
     * 
     * @param file
     *            file
     * @param defaultValue
     *            default value
     * @param <T>
     *            type of object
     * @return read object
     */
    @SuppressWarnings("unchecked")
    public static <T> T readObjectFromFile(File file, T defaultValue) {
        if (!file.exists()) {
            return defaultValue;
        }
        FileInputStream fin = null;
        ObjectInputStream oin = null;
        ByteArrayInputStream bin = null;
        try {
            byte[] byteArray = null;
            for (int i = 0; i < 3; i++) {
                try {
                    fin = new FileInputStream(file);
                    byteArray = IOUtils.toByteArray(fin);
                    break;
                } catch (Exception e) {
                    continue;
                } finally {
                    IOUtils.closeQuietly(fin);
                }
            }
            if (byteArray == null) {
                return defaultValue;
            }
            bin = new ByteArrayInputStream(byteArray);
            oin = new ObjectInputStream(bin);
            Object readObject = oin.readObject();
            return (readObject == null) ? defaultValue : (T) readObject;

        } catch (Exception e) {
            LOGGER.error("IO error for file {} : {}", file, e.getMessage());
            LOGGER.debug("Details : ", e);
        } finally {
            IOUtils.closeQuietly(bin);
            IOUtils.closeQuietly(oin);
        }
        return defaultValue;
    }
}