| /* |
| * 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.annotations.GwtIncompatible; |
| import com.google.common.base.Charsets; |
| import com.google.common.base.MoreObjects; |
| import com.google.common.collect.Lists; |
| import com.google.errorprone.annotations.CanIgnoreReturnValue; |
| import java.io.IOException; |
| import java.io.InputStream; |
| 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. |
| * |
| * <p>All method parameters must be non-null unless documented otherwise. |
| * |
| * @author Chris Nokleberg |
| * @author Ben Yu |
| * @author Colin Decker |
| * @since 1.0 |
| */ |
| @Beta |
| @GwtIncompatible |
| public final class Resources { |
| private Resources() {} |
| |
| /** |
| * 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 {@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 |
| */ |
| @CanIgnoreReturnValue // some processors won't return a useful result |
| public static <T> T readLines(URL url, Charset charset, LineProcessor<T> callback) |
| throws IOException { |
| return asCharSource(url, charset).readLines(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. |
| * |
| * <p>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<String> 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<List<String>>() { |
| final List<String> result = Lists.newArrayList(); |
| |
| @Override |
| public boolean processLine(String line) { |
| result.add(line); |
| return true; |
| } |
| |
| @Override |
| public List<String> 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. |
| * |
| * <p>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 |
| */ |
| @CanIgnoreReturnValue // being used to check if a resource exists |
| // TODO(cgdecker): maybe add a better way to check if a resource exists |
| // e.g. Optional<URL> tryGetResource or boolean resourceExists |
| public static URL getResource(String resourceName) { |
| ClassLoader loader = |
| MoreObjects.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; |
| } |
| } |