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/*
 * Copyright (C) 2007 The Guava 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 com.google.common.io;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.Beta;
import com.google.common.base.Charsets;
import com.google.common.base.Objects;
import com.google.common.collect.Lists;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.List;

/**
 * Provides utility methods for working with resources in the classpath.
 * Note that even though these methods use {@link URL} parameters, they
 * are usually not appropriate for HTTP or other non-classpath resources.
 *
 * 

All method parameters must be non-null unless documented otherwise. * * @author Chris Nokleberg * @author Ben Yu * @author Colin Decker * @since 1.0 */ @Beta public final class Resources { private Resources() {} /** * Returns a factory that will supply instances of {@link InputStream} that * read from the given URL. * * @param url the URL to read from * @return the factory * @deprecated Use {@link #asByteSource(URL)} instead. This method is * scheduled for removal in Guava 18.0. */ @Deprecated public static InputSupplier newInputStreamSupplier(URL url) { return ByteStreams.asInputSupplier(asByteSource(url)); } /** * Returns a {@link ByteSource} that reads from the given URL. * * @since 14.0 */ public static ByteSource asByteSource(URL url) { return new UrlByteSource(url); } /** * A byte source that reads from a URL using {@link URL#openStream()}. */ private static final class UrlByteSource extends ByteSource { private final URL url; private UrlByteSource(URL url) { this.url = checkNotNull(url); } @Override public InputStream openStream() throws IOException { return url.openStream(); } @Override public String toString() { return "Resources.asByteSource(" + url + ")"; } } /** * Returns a factory that will supply instances of * {@link InputStreamReader} that read a URL using the given character set. * * @param url the URL to read from * @param charset the charset used to decode the input stream; see {@link * Charsets} for helpful predefined constants * @return the factory * @deprecated Use {@link #asCharSource(URL, Charset)} instead. This method * is scheduled for removal in Guava 18.0. */ @Deprecated public static InputSupplier newReaderSupplier( URL url, Charset charset) { return CharStreams.asInputSupplier(asCharSource(url, charset)); } /** * Returns a {@link CharSource} that reads from the given URL using the given * character set. * * @since 14.0 */ public static CharSource asCharSource(URL url, Charset charset) { return asByteSource(url).asCharSource(charset); } /** * Reads all bytes from a URL into a byte array. * * @param url the URL to read from * @return a byte array containing all the bytes from the URL * @throws IOException if an I/O error occurs */ public static byte[] toByteArray(URL url) throws IOException { return asByteSource(url).read(); } /** * Reads all characters from a URL into a {@link String}, using the given * character set. * * @param url the URL to read from * @param charset the charset used to decode the input stream; see {@link * Charsets} for helpful predefined constants * @return a string containing all the characters from the URL * @throws IOException if an I/O error occurs. */ public static String toString(URL url, Charset charset) throws IOException { return asCharSource(url, charset).read(); } /** * Streams lines from a URL, stopping when our callback returns false, or we * have read all of the lines. * * @param url the URL to read from * @param charset the charset used to decode the input stream; see {@link * Charsets} for helpful predefined constants * @param callback the LineProcessor to use to handle the lines * @return the output of processing the lines * @throws IOException if an I/O error occurs */ public static T readLines(URL url, Charset charset, LineProcessor callback) throws IOException { return CharStreams.readLines(newReaderSupplier(url, charset), callback); } /** * Reads all of the lines from a URL. The lines do not include * line-termination characters, but do include other leading and trailing * whitespace. * *

This method returns a mutable {@code List}. For an * {@code ImmutableList}, use * {@code Resources.asCharSource(url, charset).readLines()}. * * @param url the URL to read from * @param charset the charset used to decode the input stream; see {@link * Charsets} for helpful predefined constants * @return a mutable {@link List} containing all the lines * @throws IOException if an I/O error occurs */ public static List readLines(URL url, Charset charset) throws IOException { // don't use asCharSource(url, charset).readLines() because that returns // an immutable list, which would change the behavior of this method return readLines(url, charset, new LineProcessor>() { final List result = Lists.newArrayList(); @Override public boolean processLine(String line) { result.add(line); return true; } @Override public List getResult() { return result; } }); } /** * Copies all bytes from a URL to an output stream. * * @param from the URL to read from * @param to the output stream * @throws IOException if an I/O error occurs */ public static void copy(URL from, OutputStream to) throws IOException { asByteSource(from).copyTo(to); } /** * Returns a {@code URL} pointing to {@code resourceName} if the resource is * found using the {@linkplain Thread#getContextClassLoader() context class * loader}. In simple environments, the context class loader will find * resources from the class path. In environments where different threads can * have different class loaders, for example app servers, the context class * loader will typically have been set to an appropriate loader for the * current thread. * *

In the unusual case where the context class loader is null, the class * loader that loaded this class ({@code Resources}) will be used instead. * * @throws IllegalArgumentException if the resource is not found */ public static URL getResource(String resourceName) { ClassLoader loader = Objects.firstNonNull( Thread.currentThread().getContextClassLoader(), Resources.class.getClassLoader()); URL url = loader.getResource(resourceName); checkArgument(url != null, "resource %s not found.", resourceName); return url; } /** * Given a {@code resourceName} that is relative to {@code contextClass}, * returns a {@code URL} pointing to the named resource. * * @throws IllegalArgumentException if the resource is not found */ public static URL getResource(Class contextClass, String resourceName) { URL url = contextClass.getResource(resourceName); checkArgument(url != null, "resource %s relative to %s not found.", resourceName, contextClass.getName()); return url; } }





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