Java tutorial
/* * Copyright (C) 2012 The Android Open Source Project * * 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.squareup.okhttp.internal; import com.squareup.okhttp.HttpUrl; import java.io.Closeable; import java.io.IOException; import java.io.InterruptedIOException; import java.io.UnsupportedEncodingException; import java.lang.reflect.Array; import java.net.ServerSocket; import java.net.Socket; import java.nio.charset.Charset; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import java.util.concurrent.ThreadFactory; import java.util.concurrent.TimeUnit; import okio.Buffer; import okio.ByteString; import okio.Source; /** Junk drawer of utility methods. */ public final class Util { public static final byte[] EMPTY_BYTE_ARRAY = new byte[0]; public static final String[] EMPTY_STRING_ARRAY = new String[0]; /** A cheap and type-safe constant for the UTF-8 Charset. */ public static final Charset UTF_8 = Charset.forName("UTF-8"); private Util() { } public static void checkOffsetAndCount(long arrayLength, long offset, long count) { if ((offset | count) < 0 || offset > arrayLength || arrayLength - offset < count) { throw new ArrayIndexOutOfBoundsException(); } } /** Returns true if two possibly-null objects are equal. */ public static boolean equal(Object a, Object b) { return a == b || (a != null && a.equals(b)); } /** * Closes {@code closeable}, ignoring any checked exceptions. Does nothing * if {@code closeable} is null. */ public static void closeQuietly(Closeable closeable) { if (closeable != null) { try { closeable.close(); } catch (RuntimeException rethrown) { throw rethrown; } catch (Exception ignored) { } } } /** * Closes {@code socket}, ignoring any checked exceptions. Does nothing if * {@code socket} is null. */ public static void closeQuietly(Socket socket) { if (socket != null) { try { socket.close(); } catch (AssertionError e) { if (!isAndroidGetsocknameError(e)) throw e; } catch (RuntimeException rethrown) { throw rethrown; } catch (Exception ignored) { } } } /** * Closes {@code serverSocket}, ignoring any checked exceptions. Does nothing if * {@code serverSocket} is null. */ public static void closeQuietly(ServerSocket serverSocket) { if (serverSocket != null) { try { serverSocket.close(); } catch (RuntimeException rethrown) { throw rethrown; } catch (Exception ignored) { } } } /** * Closes {@code a} and {@code b}. If either close fails, this completes * the other close and rethrows the first encountered exception. */ public static void closeAll(Closeable a, Closeable b) throws IOException { Throwable thrown = null; try { a.close(); } catch (Throwable e) { thrown = e; } try { b.close(); } catch (Throwable e) { if (thrown == null) thrown = e; } if (thrown == null) return; if (thrown instanceof IOException) throw (IOException) thrown; if (thrown instanceof RuntimeException) throw (RuntimeException) thrown; if (thrown instanceof Error) throw (Error) thrown; throw new AssertionError(thrown); } /** * Attempts to exhaust {@code source}, returning true if successful. This is useful when reading * a complete source is helpful, such as when doing so completes a cache body or frees a socket * connection for reuse. */ public static boolean discard(Source source, int timeout, TimeUnit timeUnit) { try { return skipAll(source, timeout, timeUnit); } catch (IOException e) { return false; } } /** * Reads until {@code in} is exhausted or the deadline has been reached. This is careful to not * extend the deadline if one exists already. */ public static boolean skipAll(Source source, int duration, TimeUnit timeUnit) throws IOException { long now = System.nanoTime(); long originalDuration = source.timeout().hasDeadline() ? source.timeout().deadlineNanoTime() - now : Long.MAX_VALUE; source.timeout().deadlineNanoTime(now + Math.min(originalDuration, timeUnit.toNanos(duration))); try { Buffer skipBuffer = new Buffer(); while (source.read(skipBuffer, 2048) != -1) { skipBuffer.clear(); } return true; // Success! The source has been exhausted. } catch (InterruptedIOException e) { return false; // We ran out of time before exhausting the source. } finally { if (originalDuration == Long.MAX_VALUE) { source.timeout().clearDeadline(); } else { source.timeout().deadlineNanoTime(now + originalDuration); } } } /** Returns a 32 character string containing an MD5 hash of {@code s}. */ public static String md5Hex(String s) { try { MessageDigest messageDigest = MessageDigest.getInstance("MD5"); byte[] md5bytes = messageDigest.digest(s.getBytes("UTF-8")); return ByteString.of(md5bytes).hex(); } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) { throw new AssertionError(e); } } /** Returns a Base 64-encoded string containing a SHA-1 hash of {@code s}. */ public static String shaBase64(String s) { try { MessageDigest messageDigest = MessageDigest.getInstance("SHA-1"); byte[] sha1Bytes = messageDigest.digest(s.getBytes("UTF-8")); return ByteString.of(sha1Bytes).base64(); } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) { throw new AssertionError(e); } } /** Returns a SHA-1 hash of {@code s}. */ public static ByteString sha1(ByteString s) { try { MessageDigest messageDigest = MessageDigest.getInstance("SHA-1"); byte[] sha1Bytes = messageDigest.digest(s.toByteArray()); return ByteString.of(sha1Bytes); } catch (NoSuchAlgorithmException e) { throw new AssertionError(e); } } /** Returns an immutable copy of {@code list}. */ public static <T> List<T> immutableList(List<T> list) { return Collections.unmodifiableList(new ArrayList<>(list)); } /** Returns an immutable list containing {@code elements}. */ public static <T> List<T> immutableList(T... elements) { return Collections.unmodifiableList(Arrays.asList(elements.clone())); } /** Returns an immutable copy of {@code map}. */ public static <K, V> Map<K, V> immutableMap(Map<K, V> map) { return Collections.unmodifiableMap(new LinkedHashMap<>(map)); } public static ThreadFactory threadFactory(final String name, final boolean daemon) { return new ThreadFactory() { @Override public Thread newThread(Runnable runnable) { Thread result = new Thread(runnable, name); result.setDaemon(daemon); return result; } }; } /** * Returns an array containing containing only elements found in {@code first} and also in * {@code second}. The returned elements are in the same order as in {@code first}. */ @SuppressWarnings("unchecked") public static <T> T[] intersect(Class<T> arrayType, T[] first, T[] second) { List<T> result = intersect(first, second); return result.toArray((T[]) Array.newInstance(arrayType, result.size())); } /** * Returns a list containing containing only elements found in {@code first} and also in * {@code second}. The returned elements are in the same order as in {@code first}. */ private static <T> List<T> intersect(T[] first, T[] second) { List<T> result = new ArrayList<>(); for (T a : first) { for (T b : second) { if (a.equals(b)) { result.add(b); break; } } } return result; } public static String hostHeader(HttpUrl url) { // TODO: square braces for IPv6 ? return url.port() != HttpUrl.defaultPort(url.scheme()) ? url.host() + ":" + url.port() : url.host(); } /** Returns {@code s} with control characters and non-ASCII characters replaced with '?'. */ public static String toHumanReadableAscii(String s) { for (int i = 0, length = s.length(), c; i < length; i += Character.charCount(c)) { c = s.codePointAt(i); if (c > '\u001f' && c < '\u007f') continue; Buffer buffer = new Buffer(); buffer.writeUtf8(s, 0, i); for (int j = i; j < length; j += Character.charCount(c)) { c = s.codePointAt(j); buffer.writeUtf8CodePoint(c > '\u001f' && c < '\u007f' ? c : '?'); } return buffer.readUtf8(); } return s; } /** * Returns true if {@code e} is due to a firmware bug fixed after Android 4.2.2. * https://code.google.com/p/android/issues/detail?id=54072 */ public static boolean isAndroidGetsocknameError(AssertionError e) { return e.getCause() != null && e.getMessage() != null && e.getMessage().contains("getsockname failed"); } public static boolean contains(String[] array, String value) { return Arrays.asList(array).contains(value); } public static String[] concat(String[] array, String value) { String[] result = new String[array.length + 1]; System.arraycopy(array, 0, result, 0, array.length); result[result.length - 1] = value; return result; } }