Java tutorial
package net; /** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. */ import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.ConnectException; import java.net.InetAddress; import java.net.InetSocketAddress; import java.net.Socket; import java.net.SocketAddress; import java.net.UnknownHostException; import java.nio.channels.SocketChannel; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import java.util.regex.Pattern; import javax.net.SocketFactory; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import util.ReflectionUtils; import conf.Configuration; public class NetUtils { private static final Log LOG = LogFactory.getLog(NetUtils.class); private static Map<String, String> hostToResolved = new HashMap<String, String>(); /** * Get the socket factory for the given class according to its * configuration parameter * <tt>hadoop.rpc.socket.factory.class.<ClassName></tt>. When no * such parameter exists then fall back on the default socket factory as * configured by <tt>hadoop.rpc.socket.factory.class.default</tt>. If * this default socket factory is not configured, then fall back on the JVM * default socket factory. * * @param conf the configuration * @param clazz the class (usually a {@link VersionedProtocol}) * @return a socket factory */ public static SocketFactory getSocketFactory(Configuration conf, Class<?> clazz) { SocketFactory factory = null; String propValue = conf.get("hadoop.rpc.socket.factory.class." + clazz.getSimpleName()); if ((propValue != null) && (propValue.length() > 0)) factory = getSocketFactoryFromProperty(conf, propValue); if (factory == null) factory = getDefaultSocketFactory(conf); return factory; } /** * Get the default socket factory as specified by the configuration * parameter <tt>hadoop.rpc.socket.factory.default</tt> * * @param conf the configuration * @return the default socket factory as specified in the configuration or * the JVM default socket factory if the configuration does not * contain a default socket factory property. */ public static SocketFactory getDefaultSocketFactory(Configuration conf) { String propValue = conf.get("hadoop.rpc.socket.factory.class.default"); if ((propValue == null) || (propValue.length() == 0)) return SocketFactory.getDefault(); return getSocketFactoryFromProperty(conf, propValue); } /** * Get the socket factory corresponding to the given proxy URI. If the * given proxy URI corresponds to an absence of configuration parameter, * returns null. If the URI is malformed raises an exception. * * @param propValue the property which is the class name of the * SocketFactory to instantiate; assumed non null and non empty. * @return a socket factory as defined in the property value. */ public static SocketFactory getSocketFactoryFromProperty(Configuration conf, String propValue) { try { Class<?> theClass = conf.getClassByName(propValue); return (SocketFactory) ReflectionUtils.newInstance(theClass, conf); } catch (ClassNotFoundException cnfe) { throw new RuntimeException("Socket Factory class not found: " + cnfe); } } /** * Util method to build socket addr from either: * <host>:<post> * <fs>://<host>:<port>/<path> */ public static InetSocketAddress createSocketAddr(String target) { return createSocketAddr(target, -1); } /** * Util method to build socket addr from either: * <host> * <host>:<post> * <fs>://<host>:<port>/<path> */ public static InetSocketAddress createSocketAddr(String target, int defaultPort) { if (target == null) { throw new IllegalArgumentException("Target address cannot be null."); } int colonIndex = target.indexOf(':'); if (colonIndex < 0 && defaultPort == -1) { throw new RuntimeException("Not a host:port pair: " + target); } String hostname = null; int port = -1; if (!target.contains("/")) { if (colonIndex == -1) { hostname = target; } else { // must be the old style <host>:<port> hostname = target.substring(0, colonIndex); port = Integer.parseInt(target.substring(colonIndex + 1)); } } if (port == -1) { port = defaultPort; } if (getStaticResolution(hostname) != null) { hostname = getStaticResolution(hostname); } return new InetSocketAddress(hostname, port); } /** * Adds a static resolution for host. This can be used for setting up * hostnames with names that are fake to point to a well known host. For e.g. * in some testcases we require to have daemons with different hostnames * running on the same machine. In order to create connections to these * daemons, one can set up mappings from those hostnames to "localhost". * {@link NetUtils#getStaticResolution(String)} can be used to query for * the actual hostname. * @param host * @param resolvedName */ public static void addStaticResolution(String host, String resolvedName) { synchronized (hostToResolved) { hostToResolved.put(host, resolvedName); } } /** * Retrieves the resolved name for the passed host. The resolved name must * have been set earlier using * {@link NetUtils#addStaticResolution(String, String)} * @param host * @return the resolution */ public static String getStaticResolution(String host) { synchronized (hostToResolved) { return hostToResolved.get(host); } } /** * This is used to get all the resolutions that were added using * {@link NetUtils#addStaticResolution(String, String)}. The return * value is a List each element of which contains an array of String * of the form String[0]=hostname, String[1]=resolved-hostname * @return the list of resolutions */ public static List<String[]> getAllStaticResolutions() { synchronized (hostToResolved) { Set<Entry<String, String>> entries = hostToResolved.entrySet(); if (entries.size() == 0) { return null; } List<String[]> l = new ArrayList<String[]>(entries.size()); for (Entry<String, String> e : entries) { l.add(new String[] { e.getKey(), e.getValue() }); } return l; } } /** * Same as getInputStream(socket, socket.getSoTimeout()).<br><br> * * From documentation for {@link #getInputStream(Socket, long)}:<br> * Returns InputStream for the socket. If the socket has an associated * SocketChannel then it returns a * {@link SocketInputStream} with the given timeout. If the socket does not * have a channel, {@link Socket#getInputStream()} is returned. In the later * case, the timeout argument is ignored and the timeout set with * {@link Socket#setSoTimeout(int)} applies for reads.<br><br> * * Any socket created using socket factories returned by {@link #NetUtils}, * must use this interface instead of {@link Socket#getInputStream()}. * * @see #getInputStream(Socket, long) * * @param socket * @return InputStream for reading from the socket. * @throws IOException */ public static InputStream getInputStream(Socket socket) throws IOException { return getInputStream(socket, socket.getSoTimeout()); } /** * Returns InputStream for the socket. If the socket has an associated * SocketChannel then it returns a * {@link SocketInputStream} with the given timeout. If the socket does not * have a channel, {@link Socket#getInputStream()} is returned. In the later * case, the timeout argument is ignored and the timeout set with * {@link Socket#setSoTimeout(int)} applies for reads.<br><br> * * Any socket created using socket factories returned by {@link #NetUtils}, * must use this interface instead of {@link Socket#getInputStream()}. * * @see Socket#getChannel() * * @param socket * @param timeout timeout in milliseconds. This may not always apply. zero * for waiting as long as necessary. * @return InputStream for reading from the socket. * @throws IOException */ public static InputStream getInputStream(Socket socket, long timeout) throws IOException { return (socket.getChannel() == null) ? socket.getInputStream() : new SocketInputStream(socket, timeout); } /** * Same as getOutputStream(socket, 0). Timeout of zero implies write will * wait until data is available.<br><br> * * From documentation for {@link #getOutputStream(Socket, long)} : <br> * Returns OutputStream for the socket. If the socket has an associated * SocketChannel then it returns a * {@link SocketOutputStream} with the given timeout. If the socket does not * have a channel, {@link Socket#getOutputStream()} is returned. In the later * case, the timeout argument is ignored and the write will wait until * data is available.<br><br> * * Any socket created using socket factories returned by {@link #NetUtils}, * must use this interface instead of {@link Socket#getOutputStream()}. * * @see #getOutputStream(Socket, long) * * @param socket * @return OutputStream for writing to the socket. * @throws IOException */ public static OutputStream getOutputStream(Socket socket) throws IOException { return getOutputStream(socket, 0); } /** * Returns OutputStream for the socket. If the socket has an associated * SocketChannel then it returns a * {@link SocketOutputStream} with the given timeout. If the socket does not * have a channel, {@link Socket#getOutputStream()} is returned. In the later * case, the timeout argument is ignored and the write will wait until * data is available.<br><br> * * Any socket created using socket factories returned by {@link #NetUtils}, * must use this interface instead of {@link Socket#getOutputStream()}. * * @see Socket#getChannel() * * @param socket * @param timeout timeout in milliseconds. This may not always apply. zero * for waiting as long as necessary. * @return OutputStream for writing to the socket. * @throws IOException */ public static OutputStream getOutputStream(Socket socket, long timeout) throws IOException { return (socket.getChannel() == null) ? socket.getOutputStream() : new SocketOutputStream(socket, timeout); } /** * This is a drop-in replacement for * {@link Socket#connect(SocketAddress, int)}. * In the case of normal sockets that don't have associated channels, this * just invokes <code>socket.connect(endpoint, timeout)</code>. If * <code>socket.getChannel()</code> returns a non-null channel, * connect is implemented using Hadoop's selectors. This is done mainly * to avoid Sun's connect implementation from creating thread-local * selectors, since Hadoop does not have control on when these are closed * and could end up taking all the available file descriptors. * * @see java.net.Socket#connect(java.net.SocketAddress, int) * * @param socket * @param endpoint * @param timeout - timeout in milliseconds */ public static void connect(Socket socket, SocketAddress endpoint, int timeout) throws IOException { if (socket == null || endpoint == null || timeout < 0) { throw new IllegalArgumentException("Illegal argument for connect()"); } SocketChannel ch = socket.getChannel(); if (ch == null) { // let the default implementation handle it. socket.connect(endpoint, timeout); } else { SocketIOWithTimeout.connect(ch, endpoint, timeout); } // There is a very rare case allowed by the TCP specification, such that // if we are trying to connect to an endpoint on the local machine, // and we end up choosing an ephemeral port equal to the destination port, // we will actually end up getting connected to ourself (ie any data we // send just comes right back). This is only possible if the target // daemon is down, so we'll treat it like connection refused. if (socket.getLocalPort() == socket.getPort() && socket.getLocalAddress().equals(socket.getInetAddress())) { LOG.info("Detected a loopback TCP socket, disconnecting it"); socket.close(); throw new ConnectException("Localhost targeted connection resulted in a loopback. " + "No daemon is listening on the target port."); } } /** * Given a string representation of a host, return its ip address * in textual presentation. * * @param name a string representation of a host: * either a textual representation its IP address or its host name * @return its IP address in the string format */ public static String normalizeHostName(String name) { if (Character.digit(name.charAt(0), 16) != -1) { // it is an IP return name; } else { try { InetAddress ipAddress = InetAddress.getByName(name); return ipAddress.getHostAddress(); } catch (UnknownHostException e) { return name; } } } /** * Given a collection of string representation of hosts, return a list of * corresponding IP addresses in the textual representation. * * @param names a collection of string representations of hosts * @return a list of corresponding IP addresses in the string format * @see #normalizeHostName(String) */ public static List<String> normalizeHostNames(Collection<String> names) { List<String> hostNames = new ArrayList<String>(names.size()); for (String name : names) { hostNames.add(normalizeHostName(name)); } return hostNames; } /** * Attempt to obtain the host name of a name specified by ip address. * Check that the node name is an ip addr and if so, attempt to determine * its host name. If the name is not an IP addr, or the actual name cannot * be determined, return null. * * @return Host name or null */ private static final Pattern ipPattern = // Pattern for matching hostname to ip:port Pattern.compile("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}:?\\d*"); public static String getHostNameOfIP(String ip) { // If name is not an ip addr, don't bother looking it up if (!ipPattern.matcher(ip).matches()) return null; String hostname = ""; try { String n = ip.substring(0, ip.indexOf(':')); hostname = InetAddress.getByName(n).getHostName(); } catch (UnknownHostException e) { return null; } return hostname; } /** * Return hostname without throwing exception. * @return hostname */ public static String getHostname() { try { return "" + InetAddress.getLocalHost(); } catch (UnknownHostException uhe) { return "" + uhe; } } }