org.nebulaframework.util.io.IOSupport.java Source code

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Here is the source code for org.nebulaframework.util.io.IOSupport.java

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/*
 * Copyright (C) 2008 Yohan Liyanage. 
 * 
 * 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.nebulaframework.util.io;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.springframework.util.Assert;

/**
 * Provides support for utility IO operations.
 * 
 * @author Yohan Liyanage
 * @version 1.0
 */
public class IOSupport {

    /**
     * Reads from the given {@codeInputStream} until end of stream
     * and returns the data read as a {@code byte[]}
     * 
     * @param is InputStream
     * 
     * @return bytes read as {@code byte[]} 
     * 
     * @throws IOException If IO error occurs during operation
     * @throws IllegalArgumentException if {@code InputStream} is {@code null}
     */
    public static byte[] readBytes(InputStream is) throws IOException, IllegalArgumentException {

        Assert.notNull(is);

        int byteRead = -1;
        List<Byte> list = new ArrayList<Byte>();

        // Read all bytes
        while ((byteRead = is.read()) != -1) {
            list.add((byte) byteRead);
        }

        // Convert to byte[] and return
        return tobyteArray(list);
    }

    /**
     * Overloaded version reads from the given {@codeInputStream} until end of stream
     * occurs or until a specified number of bytes is read (whichever occurs first). 
     * Returns the data read as a {@code byte[]}
     * 
     * @param is InputStream
     * 
     * @return bytes read as {@code byte[]} 
     * 
     * @throws IOException If IO error occurs during operation
     * @throws IllegalArgumentException if {@code InputStream} is {@code null}
     */
    public static byte[] readBytes(InputStream is, long len) throws IOException, IllegalArgumentException {

        Assert.notNull(is);
        Assert.isTrue(len > 0);

        int byteRead = -1;
        List<Byte> list = new ArrayList<Byte>();

        // Read all bytes until specified 'len' bytes are read
        while (((byteRead = is.read()) != -1) || (len > 0)) {
            list.add((byte) byteRead);
            len--;
        }

        // Convert to byte[] and return
        return tobyteArray(list);
    }

    /**
     * Support method which converts a given List of Bytes to
     * an array of primitive bytes.
     * 
     * @param list {@code List<Byte>}
     * @return A {@code byte[]} representation of given list
     * @throws IllegalArgumentException if {@code list} is {@code null}
     */
    private static byte[] tobyteArray(List<Byte> list) throws IllegalArgumentException {

        Assert.notNull(list);

        // Convert List<Byte> to byte[] and return
        byte[] bytes = new byte[list.size()];
        for (int i = 0; i < list.size(); i++) {
            bytes[i] = list.get(i);
        }

        return bytes;
    }

    /**
     * Serializes the given object and returns a byte[] representation of
     * the serialized data.
     * 
     * @param obj Object to Serialize
     * 
     * @return byte[] of serialized data
     * 
     * @throws IOException if thrown during serialization
     */
    public static <T extends Serializable> byte[] serializeToBytes(T obj) throws IOException {

        Assert.notNull(obj);

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bos);
        oos.writeObject(obj);

        return bos.toByteArray();
    }

    /**
     * Deserializes an object instance from the given byte[] 
     * of serial data.
     * 
     * @param bytes Byte[] containing serialized data
     * 
     * @return Deserialized object
     * 
     * @throws IOException if thrown during serialization
     */
    @SuppressWarnings("unchecked") // Ignore type casting Warnings
    public static <T extends Serializable> T deserializeFromBytes(byte[] bytes)
            throws IOException, ClassNotFoundException {

        Assert.notNull(bytes);

        ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(bytes));
        return (T) ois.readObject();
    }

    /**
     * Deserializes an object instance from the given byte[] 
     * of serial data, and uses the specified ClassLoader 
     * during process.
     * 
     * @param bytes Byte[] containing serialized data
     * @param classLoader ClassLoader to be used to resolve classes
     * 
     * @return Deserialized object
     * 
     * @throws IOException if thrown during serialization
     */
    @SuppressWarnings("unchecked") // Ignore type casting Warnings
    public static <T extends Serializable> T deserializeFromBytes(byte[] bytes, ClassLoader classLoader)
            throws IOException, ClassNotFoundException {

        Assert.notNull(bytes);

        // Use NebulaObjectInputStream, which allows using a specified ClassLoader
        // to resolve classes
        NebulaObjectInputStream ois = new NebulaObjectInputStream(new ByteArrayInputStream(bytes));
        ois.setClassLoader(classLoader);

        return (T) ois.readObject();
    }
}