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/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* 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. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire.internal.util;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import com.gemstone.gemfire.internal.lang.ObjectUtils;
import com.gemstone.gemfire.internal.lang.StringUtils;
/**
* Reusable Input/Output operation utility methods.
*
* @author John Blum
* @since 6.6
*/
@SuppressWarnings("unused")
public abstract class IOUtils {
public static final int BUFFER_SIZE = 4096;
/**
* Gets a fully qualified path with the path elements appended to the specified pathname using the File.separator
* character. If the pathname is unspecified (null, empty or blank) then path elements are considered relative to
* file system root, beginning with File.separator. If array of path elements are null, then the pathname is
* returned as is.
*
* @param pathname a String value indicating the base pathname.
* @param pathElements the path elements to append to pathname.
* @return the path elements appended to the pathname.
* @see java.io.File#separator
*/
public static String appendToPath(String pathname, final String... pathElements) {
if (pathElements != null) {
pathname = StringUtils.defaultIfBlank(pathname, File.separator);
for (final String pathElement : pathElements) {
pathname += (pathname.endsWith(File.separator) ? "" : File.separator);
pathname += pathElement;
}
}
return pathname;
}
/**
* Invokes the close method on any class instance implementing the Closeable interface, such as InputStreams
* and OutputStreams. Note, this method silently ignores the possible IOException resulting from the close
* invocation.
*
* @param obj an Object implementing the Closeable interface who's close method will be invoked.
*/
public static void close(final Closeable obj) {
if (obj != null) {
try {
obj.close();
}
catch (IOException ignore) {
}
}
}
/**
* Creates a path with the given path elements delimited with File.separator.
*
* @param pathElements an array of Strings constituting elements of the path.
* @return a fully constructed pathname containing the elements from the given array as path elements separated
* by File.separator.
* @see java.io.File#separator
*/
public static String createPath(final String... pathElements) {
return createPath(pathElements, File.separator);
}
/**
* Creates a path with the given path elements delimited with separator.
*
* @param pathElements an array of Strings constituting elements of the path.
* @param separator a String specifying the separator of the path. If the given String is null, then separator
* defaults to File.separator
* @return a fully constructor pathname containing the elements of the path from the given array separated
* by separator.
* @throws NullPointerException if the pathElements is null.
* @see java.io.File#separator
*/
public static String createPath(final String[] pathElements, String separator) {
separator = ObjectUtils.defaultIfNull(separator, File.separator);
final StringBuilder buffer = new StringBuilder();
for (String pathElement : pathElements) {
buffer.append(separator).append(pathElement);
}
return buffer.toString();
}
/**
* Convenience method to de-serialize a byte array back into Object form.
*
* @param objBytes an array of bytes constituting the serialized form of the Object.
* @return a Serializable Object from the array of bytes.
* @throws ClassNotFoundException if the Class type of the serialized Object cannot be resolved.
* @throws IOException if an I/O error occurs during the de-serialization process.
* @see #deserializeObject(byte[], ClassLoader)
* @see #serializeObject(Object)
* @see java.io.ByteArrayInputStream
* @see java.io.ObjectInputStream
* @see java.io.Serializable
*/
public static Object deserializeObject(final byte[] objBytes) throws IOException, ClassNotFoundException {
ObjectInputStream objIn = null;
try {
objIn = new ObjectInputStream(new ByteArrayInputStream(objBytes));
return objIn.readObject();
}
finally {
close(objIn);
}
}
/**
* Convenience method to de-serialize a byte array back into an Object who's Class type is resolved by the specific
* ClassLoader.
*
* @param objBytes an array of bytes constituting the serialized form of the Object.
* @param loader the ClassLoader used to resolve the Class type of the serialized Object.
* @return a Serializable Object from the array of bytes.
* @throws ClassNotFoundException if the Class type of the serialized Object cannot be resolved by the specified
* ClassLoader.
* @throws IOException if an I/O error occurs while de-serializing the Object from the array of bytes.
* @see #deserializeObject(byte[])
* @see #serializeObject(Object)
* @see IOUtils.ClassLoaderObjectInputStream
* @see java.io.ByteArrayInputStream
* @see java.io.Serializable
* @see java.lang.ClassLoader
*/
public static Object deserializeObject(final byte[] objBytes, final ClassLoader loader) throws IOException, ClassNotFoundException {
ObjectInputStream objIn = null;
try {
objIn = new ClassLoaderObjectInputStream(new ByteArrayInputStream(objBytes), loader);
return objIn.readObject();
}
finally {
close(objIn);
}
}
/**
* Extracts the filename from the pathname of a file system resource (file).
*
* @param pathname a String indicating the path, or location of the file system resource.
* @return a String value containing only the filename of the file system resource (file).
*/
public static String getFilename(final String pathname) {
String filename = pathname;
if (!StringUtils.isBlank(filename)) {
final int index = filename.lastIndexOf(File.separator);
filename = (index == -1 ? filename : filename.substring(index + 1));
}
return filename;
}
/**
* Determines whether the path represented by name exists in the file system of the localhost.
*
* @param pathname a String indicating the name of the path.
* @return a boolean indicating whether the path represented by name (pathname) actually exists in the file system
* of the localhost (system).
* @see com.gemstone.gemfire.internal.lang.StringUtils#isBlank(String)
* @see java.io.File#exists()
*/
public static boolean isExistingPathname(final String pathname) {
return (!StringUtils.isBlank(pathname) && new File(pathname).exists());
}
/**
* Convenience method to serialize a Serializable Object into a byte array.
*
* @param obj the Serializable Object to serialize into an array of bytes.
* @return a byte array of the serialized Object.
* @throws IOException if an I/O error occurs during the serialization process.
* @see #deserializeObject(byte[])
* @see java.io.ByteArrayOutputStream
* @see java.io.ObjectOutputStream
* @see java.io.Serializable
*/
public static byte[] serializeObject(final Object obj) throws IOException {
final ByteArrayOutputStream out = new ByteArrayOutputStream();
ObjectOutputStream objOut = null;
try {
objOut = new ObjectOutputStream(out);
objOut.writeObject(obj);
objOut.flush();
return out.toByteArray();
}
finally {
close(objOut);
}
}
/**
* Reads the contents of the specified InputStream into a byte array.
*
* @param in the InputStream to read content from.
* @return a byte array containing the content of the specified InputStream.
* @throws IOException if an I/O error occurs while reading the InputStream.
* @see java.io.ByteArrayOutputStream
* @see java.io.InputStream
*/
public static byte[] toByteArray(final InputStream in) throws IOException {
assert in != null : "The input stream to read bytes from cannot be null!";
final ByteArrayOutputStream out = new ByteArrayOutputStream();
final byte[] buffer = new byte[BUFFER_SIZE];
int bytesRead;
try {
while ((bytesRead = in.read(buffer)) != -1) {
out.write(buffer, 0, bytesRead);
out.flush();
}
}
finally {
IOUtils.close(in);
IOUtils.close(out);
}
return out.toByteArray();
}
/**
* This method attempts to get the canonical form of the specified file otherwise returns it's absolute form.
*
* @param file the java.io.File object who's canonical representation is attempted to be returned.
* @return the canonical form of the specified File or the absolute form if an IOException occurs during the
* File.getCanonicalFile call.
* @see java.io.File#getCanonicalFile()
* @see java.io.File#getAbsoluteFile()
*/
public static File tryGetCanonicalFileElseGetAbsoluteFile(final File file) {
try {
return file.getCanonicalFile();
}
catch (IOException e) {
return file.getAbsoluteFile();
}
}
/**
* This method attempts to get the canonical path of the specified file otherwise returns it's absolute path.
*
* @param file the java.io.File object who's canonical path is attempted to be returned.
* @return the canonical path of the specified File or the absolute path if an IOException occurs during the
* File.getCanonicalPath call.
* @see java.io.File#getCanonicalPath()
* @see java.io.File#getAbsolutePath()
*/
public static String tryGetCanonicalPathElseGetAbsolutePath(final File file) {
try {
return file.getCanonicalPath();
}
catch (IOException e) {
return file.getAbsolutePath();
}
}
/**
* Verifies that the specified pathname is valid and actually exists in the file system in localhost. The pathname
* is considered valid if it is not null, empty or blank and exists in the file system as a file path (which could
* represent a file or a directory).
*
* @param pathname a String indicating the file path in the file system on localhost.
* @return the pathname if valid and it exits.
* @throws FileNotFoundException if the pathname is invalid or does not exist in the file system on localhost.
* @see java.io.File#exists()
*/
public static String verifyPathnameExists(final String pathname) throws FileNotFoundException {
if (isExistingPathname(pathname)) {
return pathname;
}
throw new FileNotFoundException(String.format("Pathname (%1$s) could not be found!", pathname));
}
/**
* The ClassLoaderObjectInputStream class is a ObjectInputStream implementation that resolves the Class type of
* the Object being de-serialized with the specified ClassLoader.
*
* @see java.io.ObjectInputStream
* @see java.lang.ClassLoader
*/
protected static class ClassLoaderObjectInputStream extends ObjectInputStream {
private final ClassLoader loader;
public ClassLoaderObjectInputStream(final InputStream in, final ClassLoader loader) throws IOException {
super(in);
if (loader == null) {
throw new NullPointerException("The ClassLoader used by this ObjectInputStream to resolve Class types for serialized Objects cannot be null!");
}
this.loader = loader;
}
protected ClassLoader getClassLoader() {
return loader;
}
@Override
protected Class resolveClass(final ObjectStreamClass descriptor) throws IOException, ClassNotFoundException {
return Class.forName(descriptor.getName(), false, getClassLoader());
}
}
}