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Basic types, algorithms and utilities for Metafacture
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/*
* Copyright 2016 Christoph Böhme
*
* 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.metafacture.commons;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.util.List;
import java.util.Properties;
import java.util.function.Consumer;
/**
* Various utility methods for working with files, resources and streams.
*
* @author Christoph Böhme
* @author Markus Michael Geipel
*
*/
public final class ResourceUtil { // checkstyle-disable-line ClassDataAbstractionCoupling
static final int BUFFER_SIZE = 4096;
private ResourceUtil() {
throw new AssertionError("No instances allowed");
}
/**
* First attempts to open a file with the provided name. On fail attempts to
* open a resource identified by the name. On fail attempts to open a URL
* identified by the name.
*
* @param name name of the file, resource or the URL to open
* @return an input stream for reading the opened file, resource or URL
* @throws FileNotFoundException if all attempts fail
*/
public static InputStream getStream(final String name)
throws FileNotFoundException {
if (name == null) {
throw new IllegalArgumentException("'name' must not be null");
}
final File file = new File(name);
if (file.exists()) {
return getStream(file);
}
InputStream stream = Thread.currentThread().getContextClassLoader()
.getResourceAsStream(name);
if (stream == null) {
try {
stream = new URL(name).openStream();
}
catch (final IOException e) {
throwFileNotFoundException(name, e);
}
if (stream == null) {
throwFileNotFoundException(name, null);
}
}
return stream;
}
/**
* Gets an InputStream of a File.
*
* @param file the File.
* @return the InputStream
* @throws FileNotFoundException if the File couldn't be found
*/
public static InputStream getStream(final File file)
throws FileNotFoundException {
return new FileInputStream(file);
}
private static void throwFileNotFoundException(final String name,
final Throwable t) throws FileNotFoundException {
final FileNotFoundException e = new FileNotFoundException(
"No file, resource or URL found: " + name);
if (t != null) {
e.initCause(t);
}
throw e;
}
/**
* Gets a Reader. First attempts to open a file. On fail attempts to open the
* resource with name. On fail attempts to open name as a URL.
*
* @param name the name of the resource
* @return the Reader
* @throws FileNotFoundException if the File couldn't be found
*/
public static Reader getReader(final String name)
throws FileNotFoundException {
return new InputStreamReader(getStream(name));
}
/**
* Gets a Reader from a File.
*
* @param file the File
* @return the Reader
* @throws FileNotFoundException if the File couldn't be found
*/
public static Reader getReader(final File file) throws FileNotFoundException {
return new InputStreamReader(getStream(file));
}
/**
* Gets a Reader. First attempts to open a file. On fail attempts to open the
* resource with name. On fail attempts to open name as a URL. Uses the given
* {@link java.nio.charset.Charset charset} as encoding.
*
* @param name the name of the resource
* @param encoding the Charset
* @return the Reader
* @throws IOException if an I/O error occurs
*/
public static Reader getReader(final String name, final String encoding)
throws IOException {
return new InputStreamReader(getStream(name), encoding);
}
/**
* Gets a Reader from a File using {@link java.nio.charset.Charset charset}.
*
* @param file the File
* @param encoding the Charset
* @return the Reader
* @throws IOException if an I/O error occurs
*/
public static Reader getReader(final File file, final String encoding)
throws IOException {
return new InputStreamReader(getStream(file), encoding);
}
/**
* Attempts to return a URL for a file or resource. First, it is
* checked whether {@code name} refers to an existing local file.
* If not, the context class loader of the current thread is asked
* if {@code name} refers to a resource. Finally, the method
* attempts to interpret {@code name} as a URL.
*
* @param name reference to a file or resource maybe a URL
* @return a URL referring to a file or resource
* @throws MalformedURLException if the name is a failed URL
*/
public static URL getUrl(final String name) throws MalformedURLException {
final File file = new File(name);
if (file.exists()) {
return getUrl(file);
}
final URL resourceUrl =
Thread.currentThread().getContextClassLoader().getResource(name);
return resourceUrl != null ? resourceUrl : new URL(name);
}
/**
* Gets an URL of a File.
*
* @param file the File
* @return the URL
* @throws MalformedURLException if malformed URL has occurred
*/
public static URL getUrl(final File file) throws MalformedURLException {
return file.toURI().toURL();
}
/**
* Creates Properties based upon a location. First attempts to open a file. On
* fail attempts to open the resource with name. On fail attempts to open name
* as a URL.
*
* @param location the location of the resource
* @return the Properties
* @throws IOException if an I/O error occurs
*/
public static Properties loadProperties(final String location)
throws IOException {
try (InputStream stream = getStream(location)) {
return loadProperties(stream);
}
}
/**
* Loads properties from an InputStream.
*
* @param stream properties as InputStream
* @return the Properties
* @throws IOException if an I/O error occurs
*/
public static Properties loadProperties(final InputStream stream)
throws IOException {
final Properties properties;
properties = new Properties();
properties.load(stream);
return properties;
}
/**
* Loads properties from a URL.
*
* @param url properties as URL
* @return the Properties
* @throws IOException if an I/O error occurs
*/
public static Properties loadProperties(final URL url) throws IOException {
return loadProperties(url.openStream());
}
/**
* Loads a text file.
*
* @param location the filename
* @return the content of the file
* @throws IOException if an I/O error occurs
*/
public static String loadTextFile(final String location) throws IOException {
final StringBuilder builder = new StringBuilder();
loadTextFile(location, builder::append);
return builder.toString();
}
/**
* * Loads a text file.
*
* @param location the filename
* @param list a List of Strings to append the lines of the file to
* @return the List of Strings with the lines of the file appended
* @throws IOException if an I/O error occurs
*/
public static List loadTextFile(final String location, final List list) throws IOException {
loadTextFile(location, list::add);
return list;
}
private static void loadTextFile(final String location, final Consumer consumer) throws IOException {
try (BufferedReader reader = new BufferedReader(getReader(location))) {
String line = reader.readLine();
while (line != null) {
consumer.accept(line);
line = reader.readLine();
}
}
}
/**
* Reads an InputStream with the given Charset.
*
* @param inputStream the InputStream
* @param encoding the Charset
* @return a String of the content of the InputStream
* @throws IOException if an I/O error occurs
*/
public static String readAll(final InputStream inputStream, final Charset encoding)
throws IOException {
try (Reader reader = new InputStreamReader(inputStream, encoding)) {
return readAll(reader);
}
}
/**
* Reads a Reader.
*
* @param reader the Reader
* @return a String of the content of the Reader
* @throws IOException if an I/O error occurs
*/
public static String readAll(final Reader reader) throws IOException {
final StringBuilder loadedText = new StringBuilder();
try (Reader bufferedReader = new BufferedReader(reader)) {
final CharBuffer buffer = CharBuffer.allocate(BUFFER_SIZE);
while (bufferedReader.read(buffer) > -1) {
buffer.flip();
loadedText.append(buffer);
buffer.clear();
}
return loadedText.toString();
}
}
}