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+/*
+ *
+ * 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.
+ *
+ */
+package org.apache.qpid.junit.extensions.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Properties;
+
+/**
+ * ContextualProperties is an extension of {@link java.util.Properties} that automatically selects properties based on an
+ * environment parameter (defined by the system property {@link #ENV_SYS_PROPERTY}), the name of a class, plus a modifier
+ * (which can be used to name a method of a class) and a property key. It also supports the definition of arrays of
+ * property values using indexes. The properties are searched in the following order until a match is found:
+ *
+ * <ol>
+ * <li>environment + class name with package name + modifier + key
+ * <li>environment + class name with package name + key
+ * <li>environment + key
+ * <li>class name with package name + modifier + key
+ * <li>class name with package name + key
+ * <li>key
+ * </ol>
+ *
+ * <p>To create arrays of property values add index numbers onto the end of the property keys. An array of string values
+ * will be created with the elements of the array set to the value of the property at the matching index. Ideally the
+ * index values will be contiguous, starting at 0. This does not need to be the case however. If an array definition
+ * begins at index n, and ends at index m, Then an array big enough to hold m + 1 elements will be created and populated
+ * with values from n to m. Values before n and any missing values between n and m will be null in the array.
+ *
+ * <p>To give an example, suppose you have two different environments 'DEVELOPMENT' and 'PRODUCTION' and they each need
+ * the same properties but set to different values for each environment and some properties the same in both, you could
+ * create a properties file like:
+ *
+ * <p><code>
+ * # Project configuration properties file.<br/>
+ * <br/>
+ * # These properties are environment specific.<br/>
+ * DEVELOPMENT.debug=true<br/>
+ * PRODUCTION.debug=false<br/>
+ * <br/>
+ * # Always debug MyClass in all environments but not the myMethod method.<br/>
+ * MyClass.debug=true<br/>
+ * MyClass.myMethod.debug=false<br/>
+ * <br/>
+ * # Set up an array of my ten favourite animals. Leave elements 3 to 8 as null as I haven't decided on them yet.<br/>
+ * animals.0=cat<br/>
+ * animals.1=dog<br/>
+ * animals.2=elephant<br/>
+ * animals.9=lion<br/>
+ * <br/>
+ * # This is a default value that will be used when the environment is not known.<br/>
+ * debug=false<br/>
+ * </code>
+ *
+ * <p>The most specific definition of a property is searched for first moving out to the most general. This allows
+ * general property defaults to be set and then overiden for specific uses by some classes and modifiers.
+ *
+ * <p>A ContextualProperties object can be loaded in the same way as a java.utils.Properties. A recommended way to do
+ * this that does not assume that the properties file is a file (it could be in a jar) is to load the properties from the
+ * url for the resource lookup up on the classpath:
+ *
+ * <p><code>
+ * Properties configProperties = new ContextualProperties();<br/>
+ * configProperties.load(this.getClass().getClassLoader().getResourceAsStream("config.properties"));<br/>
+ * </code>
+ *
+ * <p>EnvironmentProperties will load the 'DEVELOPMENT.debug' property or 'PROUCTION.debug' property based on the setting
+ * of the system environment property. If a matching property for the environment cannot be found then the simple property
+ * name without the environment pre-pended onto it will be used instead. This 'use of default environments' behaviour is
+ * turned on initially but it can be disabled by calling the {@link #useDefaultEnvironments} method.
+ *
+ * <p>When a property matching a key cannot be found then the property accessor methods will always return null. If a
+ * default value for a property exists but the 'use of default environments' behavious prevents it being used then the
+ * accessor methods will return null.
+ *
+ * <p><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Automatically select properties dependant on environment, class name and modifier as well as property key.
+ * <tr><td> Convert indexed properties into arrays.
+ * </table>
+ *
+ * @author Rupert Smith
+ */
+public class ContextualProperties extends ParsedProperties
+{
+ /** The name of the system property that is used to define the environment. */
+ public static final String ENV_SYS_PROPERTY = "environment";
+
+ /**
+ * <p>Holds the iteration count down order.
+ *
+ * <p>If e = 4, b = 2, m = 1 then the iteration order or i is 7,6,4 and then if using environment defaults 3,2,0
+ * where the accessor key is:
+ * (i & e != 0 ? environment : "") + (i & b != 0 ? base : "") + (1 + m != 0 ? modifier : "") + key
+ *
+ * <p>In other words the presence or otherwise of the three least significant bits when counting down from 7
+ * specifies which of the environment, base and modifier are to be included in the key where the environment, base
+ * and modifier stand for the bits in positions 2, 1 and 0. The numbers 5 and 1 are missed out of the count because
+ * they stand for the case where the modifier is used without the base which is not done.
+ */
+ private static final int[] ORDER = new int[] { 7, 6, 4, 3, 2, 0 };
+
+ /**
+ * Defines the point in the iteration count order below which the 'use environment defaults' feature is being used.
+ */
+ private static final int ENVIRONMENT_DEFAULTS_CUTOFF = 4;
+
+ /** Defines the bit representation for the environment in the key ordering. See {@link #ORDER}. */
+ private static final int E = 4;
+
+ /** Defines the bit representation for the base in the key ordering. See {@link #ORDER}. */
+ private static final int B = 2;
+
+ /** Defines the bit representation for the modifier in the key ordering. See {@link #ORDER}. */
+ private static final int M = 1;
+
+ /** Used to hold the value of the environment system property. */
+ private String environment;
+
+ /** Used to indicate that the 'use of defaults' behaviour should be used. */
+ private boolean useDefaults = true;
+
+ /** Used to hold all the array properties. This is a mapping from property names to ArrayLists of Strings. */
+ protected Map arrayProperties = new HashMap();
+
+ /**
+ * Default constructor that builds a ContextualProperties that uses environment defaults.
+ */
+ public ContextualProperties()
+ {
+ super();
+
+ // Keep the value of the system environment property.
+ environment = System.getProperty(ENV_SYS_PROPERTY);
+ }
+
+ /**
+ * Creates a ContextualProperties that uses environment defaults and is initialized with the specified properties.
+ *
+ * @param props The properties to initialize this with.
+ */
+ public ContextualProperties(Properties props)
+ {
+ super(props);
+
+ // Keep the value of the system environment property.
+ environment = System.getProperty(ENV_SYS_PROPERTY);
+
+ // Extract any array properties as arrays.
+ createArrayProperties();
+ }
+
+ /**
+ * Parses an input stream as properties.
+ *
+ * @param inStream The input stream to read the properties from.
+ *
+ * @exception IOException If there is an IO error during reading from the input stream.
+ */
+ public void load(InputStream inStream) throws IOException
+ {
+ super.load(inStream);
+
+ // Extract any array properties as arrays.
+ createArrayProperties();
+ }
+
+ /**
+ * Tells this environment aware properties object whether it should use default environment properties without a
+ * pre-pended environment when a property for the current environment cannot be found.
+ *
+ * @param flag True to use defaults, false to not use defaults.
+ */
+ public void useDefaultEnvironments(boolean flag)
+ {
+ useDefaults = flag;
+ }
+
+ /**
+ * Looks up a property value relative to the environment, callers class and method. The default environment will be
+ * checked for a matching property if defaults are being used. In order to work out the callers class and method this
+ * method throws an exception and then searches one level up its stack frames.
+ *
+ * @param key The property key.
+ *
+ * @return The value of this property searching from the most specific definition (environment, class, method, key)
+ * to the most general (key only), unless use of default environments is turned off in which case the most general
+ * proeprty searched is (environment, key).
+ */
+ public String getProperty(String key)
+ {
+ // Try to get the callers class name and method name by examing the stack.
+ String className = null;
+ String methodName = null;
+
+ // Java 1.4 onwards only.
+ /*try
+ {
+ throw new Exception();
+ }
+ catch (Exception e)
+ {
+ StackTraceElement[] stack = e.getStackTrace();
+
+ // Check that the stack trace contains at least two elements, one for this method and one for the caller.
+ if (stack.length >= 2)
+ {
+ className = stack[1].getClassName();
+ methodName = stack[1].getMethodName();
+ }
+ }*/
+
+ // Java 1.5 onwards only.
+ StackTraceElement[] stack = Thread.currentThread().getStackTrace();
+
+ // Check that the stack trace contains at least two elements, one for this method and one for the caller.
+ if (stack.length >= 2)
+ {
+ className = stack[1].getClassName();
+ methodName = stack[1].getMethodName();
+ }
+
+ // Java 1.3 and before? Not sure, some horrible thing that parses the text spat out by printStackTrace?
+
+ return getProperty(className, methodName, key);
+ }
+
+ /**
+ * Looks up a property value relative to the environment, base class and modifier. The default environment will be
+ * checked for a matching property if defaults are being used.
+ *
+ * @param base An object of the class to retrieve properties relative to.
+ * @param modifier The modifier (which may stand for a method of the class).
+ * @param key The property key.
+ *
+ * @return The value of this property searching from the most specific definition (environment, class, modifier, key)
+ * to the most general (key only), unless use of default environments is turned off in which case the most general
+ * property searched is (environment, key).
+ */
+ public String getProperty(Object base, String modifier, String key)
+ {
+ return getProperty(base.getClass().getName(), modifier, key);
+ }
+
+ /**
+ * Looks up a property value relative to the environment, base class and modifier. The default environment will be
+ * checked for a matching property if defaults are being used.
+ *
+ * @param base The name of the class to retrieve properties relative to.
+ * @param modifier The modifier (which may stand for a method of the class).
+ * @param key The property key.
+ *
+ * @return The value of this property searching from the most specific definition (environment, class, modifier, key)
+ * to the most general (key only), unless use of default environments is turned off in which case the most general
+ * property searched is (environment, key).
+ */
+ public String getProperty(String base, String modifier, String key)
+ {
+ String result = null;
+
+ // Loop over the key orderings, from the most specific to the most general, until a matching value is found.
+ for (Iterator i = getKeyIterator(base, modifier, key); i.hasNext();)
+ {
+ String nextKey = (String) i.next();
+
+ result = super.getProperty(nextKey);
+
+ if (result != null)
+ {
+ break;
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Looks up an array property value relative to the environment, callers class and method. The default environment
+ * will be checked for a matching array property if defaults are being used. In order to work out the callers class
+ * and method this method throws an exception and then searches one level up its stack frames.
+ *
+ * @param key The property key.
+ *
+ * @return The array value of this indexed property searching from the most specific definition (environment, class,
+ * method, key) to the most general (key only), unless use of default environments is turned off in which
+ * case the most general proeprty searched is (environment, key).
+ */
+ public String[] getProperties(String key)
+ {
+ // Try to get the callers class name and method name by throwing an exception an searching the stack frames.
+ String className = null;
+ String methodName = null;
+
+ /* Java 1.4 onwards only.
+ try {
+ throw new Exception();
+ } catch (Exception e) {
+ StackTraceElement[] stack = e.getStackTrace();
+ // Check that the stack trace contains at least two elements, one for this method and one for the caller.
+ if (stack.length >= 2) {
+ className = stack[1].getClassName();
+ methodName = stack[1].getMethodName();
+ }
+ }*/
+ return getProperties(className, methodName, key);
+ }
+
+ /**
+ * Looks up an array property value relative to the environment, base class and modifier. The default environment will
+ * be checked for a matching array property if defaults are being used.
+ *
+ * @param base An object of the class to retrieve properties relative to.
+ * @param modifier The modifier (which may stand for a method of the class).
+ * @param key The property key.
+ *
+ * @return The array value of this indexed property searching from the most specific definition (environment, class,
+ * modifier, key) to the most general (key only), unless use of default environments is turned off in which
+ * case the most general proeprty searched is (environment, key).
+ */
+ public String[] getProperties(Object base, String modifier, String key)
+ {
+ return getProperties(base.getClass().getName(), modifier, key);
+ }
+
+ /**
+ * Looks up an array property value relative to the environment, base class and modifier. The default environment will
+ * be checked for a matching array property if defaults are being used.
+ *
+ * @param base The name of the class to retrieve properties relative to.
+ * @param modifier The modifier (which may stand for a method of the class).
+ * @param key The property key.
+ *
+ * @return The array value of this indexed property searching from the most specific definition (environment, class,
+ * modifier, key) to the most general (key only), unless use of default environments is turned off in which
+ * case the most general property searched is (environment, key).
+ */
+ public String[] getProperties(String base, String modifier, String key)
+ {
+ String[] result = null;
+
+ // Loop over the key orderings, from the most specific to the most general, until a matching value is found.
+ for (Iterator i = getKeyIterator(base, modifier, key); i.hasNext();)
+ {
+ String nextKey = (String) i.next();
+ ArrayList arrayList = (ArrayList) arrayProperties.get(nextKey);
+
+ if (arrayList != null)
+ {
+ result = (String[]) arrayList.toArray(new String[] {});
+
+ break;
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * For a given environment, base, modifier and key and setting of the use of default environments feature this
+ * generates an iterator that walks over the order in which to try and access properties.
+ *
+ * <p>See the {@link #ORDER} constant for an explanation of how the key ordering is generated.
+ *
+ * @param base The name of the class to retrieve properties relative to.
+ * @param modifier The modifier (which may stand for a method of the class).
+ * @param key The property key.
+ *
+ * @return An Iterator over String keys defining the order in which properties should be accessed.
+ */
+ protected Iterator getKeyIterator(final String base, final String modifier, final String key)
+ {
+ return new Iterator()
+ {
+ // The key ordering count always begins at the start of the ORDER array.
+ private int i = 0;
+
+ public boolean hasNext()
+ {
+ return (useDefaults ? ((i < ORDER.length) && (ORDER[i] > ENVIRONMENT_DEFAULTS_CUTOFF))
+ : (i < ORDER.length));
+ }
+
+ public Object next()
+ {
+ // Check that there is a next element and return null if not.
+ if (!hasNext())
+ {
+ return null;
+ }
+
+ // Get the next ordering count.
+ int o = ORDER[i];
+
+ // Do bit matching on the count to choose which elements to include in the key.
+ String result =
+ (((o & E) != 0) ? (environment + ".") : "") + (((o & B) != 0) ? (base + ".") : "")
+ + (((o & M) != 0) ? (modifier + ".") : "") + key;
+
+ // Increment the iterator to get the next key on the next call.
+ i++;
+
+ return result;
+ }
+
+ public void remove()
+ {
+ // This method is not supported.
+ throw new UnsupportedOperationException("remove() is not supported on this key order iterator as "
+ + "the ordering cannot be changed");
+ }
+ };
+ }
+
+ /**
+ * Scans all the properties in the parent Properties object and creates arrays for any array property definitions.
+ *
+ * <p>Array properties are defined with indexes. For example:
+ *
+ * <p><code>
+ * property.1=one<br/>
+ * property.2=two<br/>
+ * property.3=three<br/>
+ * </code>
+ *
+ * <p>Note that these properties will be stored as the 'empty string' or "" property array.
+ *
+ * <p><code>
+ * .1=one<br/>
+ * 2=two<br/>
+ * </code>
+ */
+ protected void createArrayProperties()
+ {
+ // Scan through all defined properties.
+ for (Object o : keySet())
+ {
+ String key = (String) o;
+ String value = super.getProperty(key);
+
+ // Split the property key into everything before the last '.' and after it.
+ int lastDotIndex = key.lastIndexOf('.');
+ String keyEnding = key.substring(lastDotIndex + 1, key.length());
+ String keyStart = key.substring(0, (lastDotIndex == -1) ? 0 : lastDotIndex);
+
+ // Check if the property key ends in an integer, in which case it is an array property.
+ int index = 0;
+
+ try
+ {
+ index = Integer.parseInt(keyEnding);
+ }
+ // The ending is not an integer so its not an array.
+ catch (NumberFormatException e)
+ {
+ // Scan the next property.
+ continue;
+ }
+
+ // Check if an array property already exists for this base name and create one if not.
+ ArrayList propArray = (ArrayList) arrayProperties.get(keyStart);
+
+ if (propArray == null)
+ {
+ propArray = new ArrayList();
+ arrayProperties.put(keyStart, propArray);
+ }
+
+ // Add the new property value to the array property for the index.
+ propArray.set(index, value);
+ }
+ }
+}