Java tutorial
package conf; /** * 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 io.Path; import io.Writable; import java.io.BufferedInputStream; import java.io.DataInput; import java.io.DataOutput; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.Reader; import java.io.Writer; import java.net.URL; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Enumeration; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.List; import java.util.ListIterator; import java.util.Map; import java.util.Properties; import java.util.Set; import java.util.StringTokenizer; import java.util.WeakHashMap; import java.util.concurrent.CopyOnWriteArrayList; import java.util.regex.Matcher; import java.util.regex.Pattern; import java.util.regex.PatternSyntaxException; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerException; import javax.xml.transform.TransformerFactory; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.codehaus.jackson.JsonFactory; import org.codehaus.jackson.JsonGenerator; import org.w3c.dom.Comment; import org.w3c.dom.DOMException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.w3c.dom.Text; import org.xml.sax.SAXException; import util.ReflectionUtils; import util.StringUtils; /** * Provides access to configuration parameters. * * <h4 id="Resources">Resources</h4> * * <p>Configurations are specified by resources. A resource contains a set of * name/value pairs as XML data. Each resource is named by either a * <code>String</code> or by a {@link Path}. If named by a <code>String</code>, * then the classpath is examined for a file with that name. If named by a * <code>Path</code>, then the local filesystem is examined directly, without * referring to the classpath. * * <p>Unless explicitly turned off, Hadoop by default specifies two * resources, loaded in-order from the classpath: <ol> * <li><tt><a href="{@docRoot}/../core-default.html">core-default.xml</a> * </tt>: Read-only defaults for hadoop.</li> * <li><tt>core-site.xml</tt>: Site-specific configuration for a given hadoop * installation.</li> * </ol> * Applications may add additional resources, which are loaded * subsequent to these resources in the order they are added. * * <h4 id="FinalParams">Final Parameters</h4> * * <p>Configuration parameters may be declared <i>final</i>. * Once a resource declares a value final, no subsequently-loaded * resource can alter that value. * For example, one might define a final parameter with: * <tt><pre> * <property> * <name>dfs.client.buffer.dir</name> * <value>/tmp/hadoop/dfs/client</value> * <b><final>true</final></b> * </property></pre></tt> * * Administrators typically define parameters as final in * <tt>core-site.xml</tt> for values that user applications may not alter. * * <h4 id="VariableExpansion">Variable Expansion</h4> * * <p>Value strings are first processed for <i>variable expansion</i>. The * available properties are:<ol> * <li>Other properties defined in this Configuration; and, if a name is * undefined here,</li> * <li>Properties in {@link System#getProperties()}.</li> * </ol> * * <p>For example, if a configuration resource contains the following property * definitions: * <tt><pre> * <property> * <name>basedir</name> * <value>/user/${<i>user.name</i>}</value> * </property> * * <property> * <name>tempdir</name> * <value>${<i>basedir</i>}/tmp</value> * </property></pre></tt> * * When <tt>conf.get("tempdir")</tt> is called, then <tt>${<i>basedir</i>}</tt> * will be resolved to another property in this Configuration, while * <tt>${<i>user.name</i>}</tt> would then ordinarily be resolved to the value * of the System property with that name. */ public class Configuration implements Iterable<Map.Entry<String, String>>, Writable { private static final Log LOG = LogFactory.getLog(Configuration.class); private boolean quietmode = true; /** * List of configuration resources. */ private ArrayList<Object> resources = new ArrayList<Object>(); /** * The value reported as the setting resource when a key is set * by code rather than a file resource. */ static final String UNKNOWN_RESOURCE = "Unknown"; /** * List of configuration parameters marked <b>final</b>. */ private Set<String> finalParameters = new HashSet<String>(); private boolean loadDefaults = true; /** * Configuration objects */ private static final WeakHashMap<Configuration, Object> REGISTRY = new WeakHashMap<Configuration, Object>(); /** * List of default Resources. Resources are loaded in the order of the list * entries */ private static final CopyOnWriteArrayList<String> defaultResources = new CopyOnWriteArrayList<String>(); private static final Map<ClassLoader, Map<String, Class<?>>> CACHE_CLASSES = new WeakHashMap<ClassLoader, Map<String, Class<?>>>(); /** * Stores the mapping of key to the resource which modifies or loads * the key most recently */ private HashMap<String, String> updatingResource; /** * Class to keep the information about the keys which replace the deprecated * ones. * * This class stores the new keys which replace the deprecated keys and also * gives a provision to have a custom message for each of the deprecated key * that is being replaced. It also provides method to get the appropriate * warning message which can be logged whenever the deprecated key is used. */ private static class DeprecatedKeyInfo { private String[] newKeys; private String customMessage; private boolean accessed; DeprecatedKeyInfo(String[] newKeys, String customMessage) { this.newKeys = newKeys; this.customMessage = customMessage; accessed = false; } /** * Method to provide the warning message. It gives the custom message if * non-null, and default message otherwise. * @param key the associated deprecated key. * @return message that is to be logged when a deprecated key is used. */ private final String getWarningMessage(String key) { String warningMessage; if (customMessage == null) { StringBuilder message = new StringBuilder(key); String deprecatedKeySuffix = " is deprecated. Instead, use "; message.append(deprecatedKeySuffix); for (int i = 0; i < newKeys.length; i++) { message.append(newKeys[i]); if (i != newKeys.length - 1) { message.append(", "); } } warningMessage = message.toString(); } else { warningMessage = customMessage; } accessed = true; return warningMessage; } } /** * Stores the deprecated keys, the new keys which replace the deprecated keys * and custom message(if any provided). */ private static Map<String, DeprecatedKeyInfo> deprecatedKeyMap = new HashMap<String, DeprecatedKeyInfo>(); /** * Adds the deprecated key to the deprecation map. * It does not override any existing entries in the deprecation map. * This is to be used only by the developers in order to add deprecation of * keys, and attempts to call this method after loading resources once, * would lead to <tt>UnsupportedOperationException</tt> * @param key * @param newKeys * @param customMessage */ public synchronized static void addDeprecation(String key, String[] newKeys, String customMessage) { if (key == null || key.length() == 0 || newKeys == null || newKeys.length == 0) { throw new IllegalArgumentException(); } if (!isDeprecated(key)) { DeprecatedKeyInfo newKeyInfo; newKeyInfo = new DeprecatedKeyInfo(newKeys, customMessage); deprecatedKeyMap.put(key, newKeyInfo); } } /** * Adds the deprecated key to the deprecation map when no custom message * is provided. * It does not override any existing entries in the deprecation map. * This is to be used only by the developers in order to add deprecation of * keys, and attempts to call this method after loading resources once, * would lead to <tt>UnsupportedOperationException</tt> * * @param key Key that is to be deprecated * @param newKeys list of keys that take up the values of deprecated key */ public synchronized static void addDeprecation(String key, String[] newKeys) { addDeprecation(key, newKeys, null); } /** * checks whether the given <code>key</code> is deprecated. * * @param key the parameter which is to be checked for deprecation * @return <code>true</code> if the key is deprecated and * <code>false</code> otherwise. */ private static boolean isDeprecated(String key) { return deprecatedKeyMap.containsKey(key); } /** * Checks for the presence of the property <code>name</code> in the * deprecation map. Returns the first of the list of new keys if present * in the deprecation map or the <code>name</code> itself. * @param name the property name * @return the first property in the list of properties mapping * the <code>name</code> or the <code>name</code> itself. */ private String handleDeprecation(String name) { if (isDeprecated(name)) { DeprecatedKeyInfo keyInfo = deprecatedKeyMap.get(name); if (!keyInfo.accessed) { LOG.warn(keyInfo.getWarningMessage(name)); } for (String newKey : keyInfo.newKeys) { if (newKey != null) { name = newKey; break; } } } return name; } static { //print deprecation warning if hadoop-site.xml is found in classpath ClassLoader cL = Thread.currentThread().getContextClassLoader(); if (cL == null) { cL = Configuration.class.getClassLoader(); } if (cL.getResource("hadoop-site.xml") != null) { LOG.warn("DEPRECATED: hadoop-site.xml found in the classpath. " + "Usage of hadoop-site.xml is deprecated. Instead use core-site.xml, " + "mapred-site.xml and hdfs-site.xml to override properties of " + "core-default.xml, mapred-default.xml and hdfs-default.xml " + "respectively"); } addDefaultResource("core-default.xml"); addDefaultResource("core-site.xml"); } private Properties properties; private Properties overlay; private ClassLoader classLoader; { classLoader = Thread.currentThread().getContextClassLoader(); if (classLoader == null) { classLoader = Configuration.class.getClassLoader(); } } /** A new configuration. */ public Configuration() { this(true); } /** A new configuration where the behavior of reading from the default * resources can be turned off. * * If the parameter {@code loadDefaults} is false, the new instance * will not load resources from the default files. * @param loadDefaults specifies whether to load from the default files */ public Configuration(boolean loadDefaults) { this.loadDefaults = loadDefaults; updatingResource = new HashMap<String, String>(); synchronized (Configuration.class) { REGISTRY.put(this, null); } } /** * A new configuration with the same settings cloned from another. * * @param other the configuration from which to clone settings. */ @SuppressWarnings("unchecked") public Configuration(Configuration other) { this.resources = (ArrayList) other.resources.clone(); synchronized (other) { if (other.properties != null) { this.properties = (Properties) other.properties.clone(); } if (other.overlay != null) { this.overlay = (Properties) other.overlay.clone(); } this.updatingResource = new HashMap<String, String>(other.updatingResource); } this.finalParameters = new HashSet<String>(other.finalParameters); synchronized (Configuration.class) { REGISTRY.put(this, null); } this.classLoader = other.classLoader; this.loadDefaults = other.loadDefaults; setQuietMode(other.getQuietMode()); } /** * Add a default resource. Resources are loaded in the order of the resources * added. * @param name file name. File should be present in the classpath. */ public static synchronized void addDefaultResource(String name) { if (!defaultResources.contains(name)) { defaultResources.add(name); for (Configuration conf : REGISTRY.keySet()) { if (conf.loadDefaults) { conf.reloadConfiguration(); } } } } /** * Add a configuration resource. * * The properties of this resource will override properties of previously * added resources, unless they were marked <a href="#Final">final</a>. * * @param name resource to be added, the classpath is examined for a file * with that name. */ public void addResource(String name) { addResourceObject(name); } /** * Add a configuration resource. * * The properties of this resource will override properties of previously * added resources, unless they were marked <a href="#Final">final</a>. * * @param url url of the resource to be added, the local filesystem is * examined directly to find the resource, without referring to * the classpath. */ public void addResource(URL url) { addResourceObject(url); } /** * Add a configuration resource. * * The properties of this resource will override properties of previously * added resources, unless they were marked <a href="#Final">final</a>. * * @param in InputStream to deserialize the object from. */ public void addResource(InputStream in) { addResourceObject(in); } /** * Reload configuration from previously added resources. * * This method will clear all the configuration read from the added * resources, and final parameters. This will make the resources to * be read again before accessing the values. Values that are added * via set methods will overlay values read from the resources. */ public synchronized void reloadConfiguration() { properties = null; // trigger reload finalParameters.clear(); // clear site-limits } private synchronized void addResourceObject(Object resource) { resources.add(resource); // add to resources reloadConfiguration(); } private static Pattern varPat = Pattern.compile("\\$\\{[^\\}\\$\u0020]+\\}"); private static int MAX_SUBST = 20; private String substituteVars(String expr) { if (expr == null) { return null; } Matcher match = varPat.matcher(""); String eval = expr; for (int s = 0; s < MAX_SUBST; s++) { match.reset(eval); if (!match.find()) { return eval; } String var = match.group(); var = var.substring(2, var.length() - 1); // remove ${ .. } String val = null; try { val = System.getProperty(var); } catch (SecurityException se) { LOG.warn("Unexpected SecurityException in Configuration", se); } if (val == null) { val = getRaw(var); } if (val == null) { return eval; // return literal ${var}: var is unbound } // substitute eval = eval.substring(0, match.start()) + val + eval.substring(match.end()); } throw new IllegalStateException("Variable substitution depth too large: " + MAX_SUBST + " " + expr); } /** * Get the value of the <code>name</code> property, <code>null</code> if * no such property exists. If the key is deprecated, it returns the value of * the first key which replaces the deprecated key and is not null * * Values are processed for <a href="#VariableExpansion">variable expansion</a> * before being returned. * * @param name the property name. * @return the value of the <code>name</code> or its replacing property, * or null if no such property exists. */ public String get(String name) { name = handleDeprecation(name); return substituteVars(getProps().getProperty(name)); } /** * Get the value of the <code>name</code> property, without doing * <a href="#VariableExpansion">variable expansion</a>.If the key is * deprecated, it returns the value of the first key which replaces * the deprecated key and is not null. * * @param name the property name. * @return the value of the <code>name</code> property or * its replacing property and null if no such property exists. */ public String getRaw(String name) { name = handleDeprecation(name); return getProps().getProperty(name); } /** * Set the <code>value</code> of the <code>name</code> property. If * <code>name</code> is deprecated, it sets the <code>value</code> to the keys * that replace the deprecated key. * * @param name property name. * @param value property value. */ public void set(String name, String value) { if (deprecatedKeyMap.isEmpty()) { getProps(); } if (!isDeprecated(name)) { getOverlay().setProperty(name, value); getProps().setProperty(name, value); updatingResource.put(name, UNKNOWN_RESOURCE); } else { DeprecatedKeyInfo keyInfo = deprecatedKeyMap.get(name); LOG.warn(keyInfo.getWarningMessage(name)); for (String newKey : keyInfo.newKeys) { getOverlay().setProperty(newKey, value); getProps().setProperty(newKey, value); } } } /** * Sets a property if it is currently unset. * @param name the property name * @param value the new value */ public void setIfUnset(String name, String value) { if (get(name) == null) { set(name, value); } } private synchronized Properties getOverlay() { if (overlay == null) { overlay = new Properties(); } return overlay; } /** * Get the value of the <code>name</code>. If the key is deprecated, * it returns the value of the first key which replaces the deprecated key * and is not null. * If no such property exists, * then <code>defaultValue</code> is returned. * * @param name property name. * @param defaultValue default value. * @return property value, or <code>defaultValue</code> if the property * doesn't exist. */ public String get(String name, String defaultValue) { name = handleDeprecation(name); return substituteVars(getProps().getProperty(name, defaultValue)); } /** * Get the value of the <code>name</code> property as an <code>int</code>. * * If no such property exists, or if the specified value is not a valid * <code>int</code>, then <code>defaultValue</code> is returned. * * @param name property name. * @param defaultValue default value. * @return property value as an <code>int</code>, * or <code>defaultValue</code>. */ public int getInt(String name, int defaultValue) { String valueString = get(name); if (valueString == null) return defaultValue; try { String hexString = getHexDigits(valueString); if (hexString != null) { return Integer.parseInt(hexString, 16); } return Integer.parseInt(valueString); } catch (NumberFormatException e) { return defaultValue; } } /** * Set the value of the <code>name</code> property to an <code>int</code>. * * @param name property name. * @param value <code>int</code> value of the property. */ public void setInt(String name, int value) { set(name, Integer.toString(value)); } /** * Get the value of the <code>name</code> property as a <code>long</code>. * If no such property is specified, or if the specified value is not a valid * <code>long</code>, then <code>defaultValue</code> is returned. * * @param name property name. * @param defaultValue default value. * @return property value as a <code>long</code>, * or <code>defaultValue</code>. */ public long getLong(String name, long defaultValue) { String valueString = get(name); if (valueString == null) return defaultValue; try { String hexString = getHexDigits(valueString); if (hexString != null) { return Long.parseLong(hexString, 16); } return Long.parseLong(valueString); } catch (NumberFormatException e) { return defaultValue; } } private String getHexDigits(String value) { boolean negative = false; String str = value; String hexString = null; if (value.startsWith("-")) { negative = true; str = value.substring(1); } if (str.startsWith("0x") || str.startsWith("0X")) { hexString = str.substring(2); if (negative) { hexString = "-" + hexString; } return hexString; } return null; } /** * Set the value of the <code>name</code> property to a <code>long</code>. * * @param name property name. * @param value <code>long</code> value of the property. */ public void setLong(String name, long value) { set(name, Long.toString(value)); } /** * Get the value of the <code>name</code> property as a <code>float</code>. * If no such property is specified, or if the specified value is not a valid * <code>float</code>, then <code>defaultValue</code> is returned. * * @param name property name. * @param defaultValue default value. * @return property value as a <code>float</code>, * or <code>defaultValue</code>. */ public float getFloat(String name, float defaultValue) { String valueString = get(name); if (valueString == null) return defaultValue; try { return Float.parseFloat(valueString); } catch (NumberFormatException e) { return defaultValue; } } /** * Set the value of the <code>name</code> property to a <code>float</code>. * * @param name property name. * @param value property value. */ public void setFloat(String name, float value) { set(name, Float.toString(value)); } /** * Get the value of the <code>name</code> property as a <code>boolean</code>. * If no such property is specified, or if the specified value is not a valid * <code>boolean</code>, then <code>defaultValue</code> is returned. * * @param name property name. * @param defaultValue default value. * @return property value as a <code>boolean</code>, * or <code>defaultValue</code>. */ public boolean getBoolean(String name, boolean defaultValue) { String valueString = get(name); if ("true".equals(valueString)) return true; else if ("false".equals(valueString)) return false; else return defaultValue; } /** * Set the value of the <code>name</code> property to a <code>boolean</code>. * * @param name property name. * @param value <code>boolean</code> value of the property. */ public void setBoolean(String name, boolean value) { set(name, Boolean.toString(value)); } /** * Set the given property, if it is currently unset. * @param name property name * @param value new value */ public void setBooleanIfUnset(String name, boolean value) { setIfUnset(name, Boolean.toString(value)); } /** * Set the value of the <code>name</code> property to the given type. This * is equivalent to <code>set(<name>, value.toString())</code>. * @param name property name * @param value new value */ public <T extends Enum<T>> void setEnum(String name, T value) { set(name, value.toString()); } /** * Return value matching this enumerated type. * @param name Property name * @param defaultValue Value returned if no mapping exists * @throws IllegalArgumentException If mapping is illegal for the type * provided */ public <T extends Enum<T>> T getEnum(String name, T defaultValue) { final String val = get(name); return null == val ? defaultValue : Enum.valueOf(defaultValue.getDeclaringClass(), val); } /** * Get the value of the <code>name</code> property as a <code>Pattern</code>. * If no such property is specified, or if the specified value is not a valid * <code>Pattern</code>, then <code>DefaultValue</code> is returned. * * @param name property name * @param defaultValue default value * @return property value as a compiled Pattern, or defaultValue */ public Pattern getPattern(String name, Pattern defaultValue) { String valString = get(name); if (null == valString || "".equals(valString)) { return defaultValue; } try { return Pattern.compile(valString); } catch (PatternSyntaxException pse) { LOG.warn("Regular expression '" + valString + "' for property '" + name + "' not valid. Using default", pse); return defaultValue; } } /** * Set the given property to <code>Pattern</code>. * If the pattern is passed as null, sets the empty pattern which results in * further calls to getPattern(...) returning the default value. * * @param name property name * @param pattern new value */ public void setPattern(String name, Pattern pattern) { if (null == pattern) { set(name, null); } else { set(name, pattern.pattern()); } } /** * A class that represents a set of positive integer ranges. It parses * strings of the form: "2-3,5,7-" where ranges are separated by comma and * the lower/upper bounds are separated by dash. Either the lower or upper * bound may be omitted meaning all values up to or over. So the string * above means 2, 3, 5, and 7, 8, 9, ... */ public static class IntegerRanges { private static class Range { int start; int end; } List<Range> ranges = new ArrayList<Range>(); public IntegerRanges() { } public IntegerRanges(String newValue) { StringTokenizer itr = new StringTokenizer(newValue, ","); while (itr.hasMoreTokens()) { String rng = itr.nextToken().trim(); String[] parts = rng.split("-", 3); if (parts.length < 1 || parts.length > 2) { throw new IllegalArgumentException("integer range badly formed: " + rng); } Range r = new Range(); r.start = convertToInt(parts[0], 0); if (parts.length == 2) { r.end = convertToInt(parts[1], Integer.MAX_VALUE); } else { r.end = r.start; } if (r.start > r.end) { throw new IllegalArgumentException( "IntegerRange from " + r.start + " to " + r.end + " is invalid"); } ranges.add(r); } } /** * Convert a string to an int treating empty strings as the default value. * @param value the string value * @param defaultValue the value for if the string is empty * @return the desired integer */ private static int convertToInt(String value, int defaultValue) { String trim = value.trim(); if (trim.length() == 0) { return defaultValue; } return Integer.parseInt(trim); } /** * Is the given value in the set of ranges * @param value the value to check * @return is the value in the ranges? */ public boolean isIncluded(int value) { for (Range r : ranges) { if (r.start <= value && value <= r.end) { return true; } } return false; } @Override public String toString() { StringBuilder result = new StringBuilder(); boolean first = true; for (Range r : ranges) { if (first) { first = false; } else { result.append(','); } result.append(r.start); result.append('-'); result.append(r.end); } return result.toString(); } } /** * Parse the given attribute as a set of integer ranges * @param name the attribute name * @param defaultValue the default value if it is not set * @return a new set of ranges from the configured value */ public IntegerRanges getRange(String name, String defaultValue) { return new IntegerRanges(get(name, defaultValue)); } /** * Get the comma delimited values of the <code>name</code> property as * a collection of <code>String</code>s. * If no such property is specified then empty collection is returned. * <p> * This is an optimized version of {@link #getStrings(String)} * * @param name property name. * @return property value as a collection of <code>String</code>s. */ public Collection<String> getStringCollection(String name) { String valueString = get(name); return StringUtils.getStringCollection(valueString); } /** * Get the comma delimited values of the <code>name</code> property as * an array of <code>String</code>s. * If no such property is specified then <code>null</code> is returned. * * @param name property name. * @return property value as an array of <code>String</code>s, * or <code>null</code>. */ public String[] getStrings(String name) { String valueString = get(name); return StringUtils.getStrings(valueString); } /** * Get the comma delimited values of the <code>name</code> property as * an array of <code>String</code>s. * If no such property is specified then default value is returned. * * @param name property name. * @param defaultValue The default value * @return property value as an array of <code>String</code>s, * or default value. */ public String[] getStrings(String name, String... defaultValue) { String valueString = get(name); if (valueString == null) { return defaultValue; } else { return StringUtils.getStrings(valueString); } } /** * Get the comma delimited values of the <code>name</code> property as * a collection of <code>String</code>s, trimmed of the leading and trailing whitespace. * If no such property is specified then empty <code>Collection</code> is returned. * * @param name property name. * @return property value as a collection of <code>String</code>s, or empty <code>Collection</code> */ public Collection<String> getTrimmedStringCollection(String name) { String valueString = get(name); if (null == valueString) { Collection<String> empty = Collections.emptyList(); return empty; } return StringUtils.getTrimmedStringCollection(valueString); } /** * Get the comma delimited values of the <code>name</code> property as * an array of <code>String</code>s, trimmed of the leading and trailing whitespace. * If no such property is specified then an empty array is returned. * * @param name property name. * @return property value as an array of trimmed <code>String</code>s, * or empty array. */ public String[] getTrimmedStrings(String name) { String valueString = get(name); return StringUtils.getTrimmedStrings(valueString); } /** * Get the comma delimited values of the <code>name</code> property as * an array of <code>String</code>s, trimmed of the leading and trailing whitespace. * If no such property is specified then default value is returned. * * @param name property name. * @param defaultValue The default value * @return property value as an array of trimmed <code>String</code>s, * or default value. */ public String[] getTrimmedStrings(String name, String... defaultValue) { String valueString = get(name); if (null == valueString) { return defaultValue; } else { return StringUtils.getTrimmedStrings(valueString); } } /** * Set the array of string values for the <code>name</code> property as * as comma delimited values. * * @param name property name. * @param values The values */ public void setStrings(String name, String... values) { set(name, StringUtils.arrayToString(values)); } /** * Load a class by name. * * @param name the class name. * @return the class object. * @throws ClassNotFoundException if the class is not found. */ public Class<?> getClassByName(String name) throws ClassNotFoundException { Map<String, Class<?>> map; synchronized (CACHE_CLASSES) { map = CACHE_CLASSES.get(classLoader); if (map == null) { map = Collections.synchronizedMap(new WeakHashMap<String, Class<?>>()); CACHE_CLASSES.put(classLoader, map); } } Class clazz = map.get(name); if (clazz == null) { clazz = Class.forName(name, true, classLoader); if (clazz != null) { // two putters can race here, but they'll put the same class map.put(name, clazz); } } return clazz; } /** * Get the value of the <code>name</code> property * as an array of <code>Class</code>. * The value of the property specifies a list of comma separated class names. * If no such property is specified, then <code>defaultValue</code> is * returned. * * @param name the property name. * @param defaultValue default value. * @return property value as a <code>Class[]</code>, * or <code>defaultValue</code>. */ public Class<?>[] getClasses(String name, Class<?>... defaultValue) { String[] classnames = getStrings(name); if (classnames == null) return defaultValue; try { Class<?>[] classes = new Class<?>[classnames.length]; for (int i = 0; i < classnames.length; i++) { classes[i] = getClassByName(classnames[i]); } return classes; } catch (ClassNotFoundException e) { throw new RuntimeException(e); } } /** * Get the value of the <code>name</code> property as a <code>Class</code>. * If no such property is specified, then <code>defaultValue</code> is * returned. * * @param name the class name. * @param defaultValue default value. * @return property value as a <code>Class</code>, * or <code>defaultValue</code>. */ public Class<?> getClass(String name, Class<?> defaultValue) { String valueString = get(name); if (valueString == null) return defaultValue; try { return getClassByName(valueString); } catch (ClassNotFoundException e) { throw new RuntimeException(e); } } /** * Get the value of the <code>name</code> property as a <code>Class</code> * implementing the interface specified by <code>xface</code>. * * If no such property is specified, then <code>defaultValue</code> is * returned. * * An exception is thrown if the returned class does not implement the named * interface. * * @param name the class name. * @param defaultValue default value. * @param xface the interface implemented by the named class. * @return property value as a <code>Class</code>, * or <code>defaultValue</code>. */ public <U> Class<? extends U> getClass(String name, Class<? extends U> defaultValue, Class<U> xface) { try { Class<?> theClass = getClass(name, defaultValue); if (theClass != null && !xface.isAssignableFrom(theClass)) throw new RuntimeException(theClass + " not " + xface.getName()); else if (theClass != null) return theClass.asSubclass(xface); else return null; } catch (Exception e) { throw new RuntimeException(e); } } /** * Get the value of the <code>name</code> property as a <code>List</code> * of objects implementing the interface specified by <code>xface</code>. * * An exception is thrown if any of the classes does not exist, or if it does * not implement the named interface. * * @param name the property name. * @param xface the interface implemented by the classes named by * <code>name</code>. * @return a <code>List</code> of objects implementing <code>xface</code>. */ @SuppressWarnings("unchecked") public <U> List<U> getInstances(String name, Class<U> xface) { List<U> ret = new ArrayList<U>(); Class<?>[] classes = getClasses(name); for (Class<?> cl : classes) { if (!xface.isAssignableFrom(cl)) { throw new RuntimeException(cl + " does not implement " + xface); } ret.add((U) ReflectionUtils.newInstance(cl, this)); } return ret; } /** * Set the value of the <code>name</code> property to the name of a * <code>theClass</code> implementing the given interface <code>xface</code>. * * An exception is thrown if <code>theClass</code> does not implement the * interface <code>xface</code>. * * @param name property name. * @param theClass property value. * @param xface the interface implemented by the named class. */ public void setClass(String name, Class<?> theClass, Class<?> xface) { if (!xface.isAssignableFrom(theClass)) throw new RuntimeException(theClass + " not " + xface.getName()); set(name, theClass.getName()); } /** * Get a local file name under a directory named in <i>dirsProp</i> with * the given <i>path</i>. If <i>dirsProp</i> contains multiple directories, * then one is chosen based on <i>path</i>'s hash code. If the selected * directory does not exist, an attempt is made to create it. * * @param dirsProp directory in which to locate the file. * @param path file-path. * @return local file under the directory with the given path. */ public File getFile(String dirsProp, String path) throws IOException { String[] dirs = getStrings(dirsProp); int hashCode = path.hashCode(); for (int i = 0; i < dirs.length; i++) { // try each local dir int index = (hashCode + i & Integer.MAX_VALUE) % dirs.length; File file = new File(dirs[index], path); File dir = file.getParentFile(); if (dir.exists() || dir.mkdirs()) { return file; } } throw new IOException("No valid local directories in property: " + dirsProp); } /** * Get the {@link URL} for the named resource. * * @param name resource name. * @return the url for the named resource. */ public URL getResource(String name) { return classLoader.getResource(name); } /** * Get an input stream attached to the configuration resource with the * given <code>name</code>. * * @param name configuration resource name. * @return an input stream attached to the resource. */ public InputStream getConfResourceAsInputStream(String name) { try { URL url = getResource(name); if (url == null) { LOG.info(name + " not found"); return null; } else { LOG.info("found resource " + name + " at " + url); } return url.openStream(); } catch (Exception e) { return null; } } /** * Get a {@link Reader} attached to the configuration resource with the * given <code>name</code>. * * @param name configuration resource name. * @return a reader attached to the resource. */ public Reader getConfResourceAsReader(String name) { try { URL url = getResource(name); if (url == null) { LOG.info(name + " not found"); return null; } else { LOG.info("found resource " + name + " at " + url); } return new InputStreamReader(url.openStream()); } catch (Exception e) { return null; } } protected synchronized Properties getProps() { if (properties == null) { properties = new Properties(); loadResources(properties, resources, quietmode); if (overlay != null) { properties.putAll(overlay); for (Map.Entry<Object, Object> item : overlay.entrySet()) { updatingResource.put((String) item.getKey(), UNKNOWN_RESOURCE); } } } return properties; } /** * Return the number of keys in the configuration. * * @return number of keys in the configuration. */ public int size() { return getProps().size(); } /** * Clears all keys from the configuration. */ public void clear() { getProps().clear(); getOverlay().clear(); } /** * Get an {@link Iterator} to go through the list of <code>String</code> * key-value pairs in the configuration. * * @return an iterator over the entries. */ public Iterator<Map.Entry<String, String>> iterator() { // Get a copy of just the string to string pairs. After the old object // methods that allow non-strings to be put into configurations are removed, // we could replace properties with a Map<String,String> and get rid of this // code. Map<String, String> result = new HashMap<String, String>(); for (Map.Entry<Object, Object> item : getProps().entrySet()) { if (item.getKey() instanceof String && item.getValue() instanceof String) { result.put((String) item.getKey(), (String) item.getValue()); } } return result.entrySet().iterator(); } private void loadResources(Properties properties, ArrayList resources, boolean quiet) { if (loadDefaults) { for (String resource : defaultResources) { loadResource(properties, resource, quiet); } //support the hadoop-site.xml as a deprecated case if (getResource("hadoop-site.xml") != null) { loadResource(properties, "hadoop-site.xml", quiet); } } for (Object resource : resources) { loadResource(properties, resource, quiet); } } private void loadResource(Properties properties, Object name, boolean quiet) { } private void loadProperty(Properties properties, Object name, String attr, String value, boolean finalParameter) { if (value != null) { if (!finalParameters.contains(attr)) { properties.setProperty(attr, value); updatingResource.put(attr, name.toString()); } else { LOG.warn(name + ":an attempt to override final parameter: " + attr + "; Ignoring."); } } if (finalParameter) { finalParameters.add(attr); } } /** * Write out the non-default properties in this configuration to the given * {@link OutputStream}. * * @param out the output stream to write to. */ public void writeXml(OutputStream out) throws IOException { writeXml(new OutputStreamWriter(out)); } /** * Write out the non-default properties in this configuration to the given * {@link Writer}. * * @param out the writer to write to. */ public synchronized void writeXml(Writer out) throws IOException { Properties properties = getProps(); try { Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument(); Element conf = doc.createElement("configuration"); doc.appendChild(conf); conf.appendChild(doc.createTextNode("\n")); for (Enumeration e = properties.keys(); e.hasMoreElements();) { String name = (String) e.nextElement(); Object object = properties.get(name); String value = null; if (object instanceof String) { value = (String) object; } else { continue; } Element propNode = doc.createElement("property"); conf.appendChild(propNode); if (updatingResource != null) { Comment commentNode = doc.createComment("Loaded from " + updatingResource.get(name)); propNode.appendChild(commentNode); } Element nameNode = doc.createElement("name"); nameNode.appendChild(doc.createTextNode(name)); propNode.appendChild(nameNode); Element valueNode = doc.createElement("value"); valueNode.appendChild(doc.createTextNode(value)); propNode.appendChild(valueNode); conf.appendChild(doc.createTextNode("\n")); } DOMSource source = new DOMSource(doc); StreamResult result = new StreamResult(out); TransformerFactory transFactory = TransformerFactory.newInstance(); Transformer transformer = transFactory.newTransformer(); transformer.transform(source, result); } catch (TransformerException te) { throw new IOException(te); } catch (ParserConfigurationException pe) { throw new IOException(pe); } } /** * Writes out all the parameters and their properties (final and resource) to * the given {@link Writer} * The format of the output would be * { "properties" : [ {key1,value1,key1.isFinal,key1.resource}, {key2,value2, * key2.isFinal,key2.resource}... ] } * It does not output the parameters of the configuration object which is * loaded from an input stream. * @param out the Writer to write to * @throws IOException */ public static void dumpConfiguration(Configuration config, Writer out) throws IOException { JsonFactory dumpFactory = new JsonFactory(); JsonGenerator dumpGenerator = dumpFactory.createJsonGenerator(out); dumpGenerator.writeStartObject(); dumpGenerator.writeFieldName("properties"); dumpGenerator.writeStartArray(); dumpGenerator.flush(); synchronized (config) { for (Map.Entry<Object, Object> item : config.getProps().entrySet()) { dumpGenerator.writeStartObject(); dumpGenerator.writeStringField("key", (String) item.getKey()); dumpGenerator.writeStringField("value", config.get((String) item.getKey())); dumpGenerator.writeBooleanField("isFinal", config.finalParameters.contains(item.getKey())); dumpGenerator.writeStringField("resource", config.updatingResource.get(item.getKey())); dumpGenerator.writeEndObject(); } } dumpGenerator.writeEndArray(); dumpGenerator.writeEndObject(); dumpGenerator.flush(); } /** * Get the {@link ClassLoader} for this job. * * @return the correct class loader. */ public ClassLoader getClassLoader() { return classLoader; } /** * Set the class loader that will be used to load the various objects. * * @param classLoader the new class loader. */ public void setClassLoader(ClassLoader classLoader) { this.classLoader = classLoader; } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("Configuration: "); if (loadDefaults) { toString(defaultResources, sb); if (resources.size() > 0) { sb.append(", "); } } toString(resources, sb); return sb.toString(); } private <T> void toString(List<T> resources, StringBuilder sb) { ListIterator<T> i = resources.listIterator(); while (i.hasNext()) { if (i.nextIndex() != 0) { sb.append(", "); } sb.append(i.next()); } } /** * Set the quietness-mode. * * In the quiet-mode, error and informational messages might not be logged. * * @param quietmode <code>true</code> to set quiet-mode on, <code>false</code> * to turn it off. */ public synchronized void setQuietMode(boolean quietmode) { this.quietmode = quietmode; } synchronized boolean getQuietMode() { return this.quietmode; } /** For debugging. List non-default properties to the terminal and exit. */ public static void main(String[] args) throws Exception { new Configuration().writeXml(System.out); } @Override public void write(DataOutput out) throws IOException { } @Override public void readFields(DataInput in) throws IOException { } }