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Diffstat (limited to 'trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/ContextualProperties.java')
-rw-r--r-- | trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/ContextualProperties.java | 494 |
1 files changed, 494 insertions, 0 deletions
diff --git a/trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/ContextualProperties.java b/trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/ContextualProperties.java new file mode 100644 index 0000000000..14de96d165 --- /dev/null +++ b/trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/ContextualProperties.java @@ -0,0 +1,494 @@ +/* + * + * 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); + } + } +} |