org.apache.commons.configuration.ConfigurationUtils Maven / Gradle / Ivy
/*
* 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.commons.configuration;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.Iterator;
import org.apache.commons.configuration.event.ConfigurationErrorEvent;
import org.apache.commons.configuration.event.ConfigurationErrorListener;
import org.apache.commons.configuration.event.EventSource;
import org.apache.commons.configuration.tree.ExpressionEngine;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.SystemUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Miscellaneous utility methods for configurations.
*
* @see ConfigurationConverter Utility methods to convert configurations.
*
* @author Herve Quiroz
* @author Oliver Heger
* @author Emmanuel Bourg
* @version $Revision: 720600 $, $Date: 2008-11-25 22:20:01 +0100 (Di, 25 Nov 2008) $
*/
public final class ConfigurationUtils
{
/** Constant for the file URL protocol.*/
static final String PROTOCOL_FILE = "file";
/** Constant for the resource path separator.*/
static final String RESOURCE_PATH_SEPARATOR = "/";
/** Constant for the name of the clone() method.*/
private static final String METHOD_CLONE = "clone";
/** Constant for Java version 1.4.*/
private static final float JAVA_1_4 = 1.4f;
/** The logger.*/
private static Log log = LogFactory.getLog(ConfigurationUtils.class);
/**
* Private constructor. Prevents instances from being created.
*/
private ConfigurationUtils()
{
// to prevent instantiation...
}
/**
* Dump the configuration key/value mappings to some ouput stream.
*
* @param configuration the configuration
* @param out the output stream to dump the configuration to
*/
public static void dump(Configuration configuration, PrintStream out)
{
dump(configuration, new PrintWriter(out));
}
/**
* Dump the configuration key/value mappings to some writer.
*
* @param configuration the configuration
* @param out the writer to dump the configuration to
*/
public static void dump(Configuration configuration, PrintWriter out)
{
Iterator keys = configuration.getKeys();
while (keys.hasNext())
{
String key = (String) keys.next();
Object value = configuration.getProperty(key);
out.print(key);
out.print("=");
out.print(value);
if (keys.hasNext())
{
out.println();
}
}
out.flush();
}
/**
* Get a string representation of the key/value mappings of a
* configuration.
*
* @param configuration the configuration
* @return a string representation of the configuration
*/
public static String toString(Configuration configuration)
{
StringWriter writer = new StringWriter();
dump(configuration, new PrintWriter(writer));
return writer.toString();
}
/**
* Copy all properties from the source configuration to the target
* configuration. Properties in the target configuration are replaced with
* the properties with the same key in the source configuration.
* Note: This method is not able to handle some specifics of
* configurations derived from AbstractConfiguration (e.g.
* list delimiters). For a full support of all of these features the
* copy() method of AbstractConfiguration should
* be used. In a future release this method might become deprecated.
*
* @param source the source configuration
* @param target the target configuration
* @since 1.1
*/
public static void copy(Configuration source, Configuration target)
{
Iterator keys = source.getKeys();
while (keys.hasNext())
{
String key = (String) keys.next();
target.setProperty(key, source.getProperty(key));
}
}
/**
* Append all properties from the source configuration to the target
* configuration. Properties in the source configuration are appended to
* the properties with the same key in the target configuration.
* Note: This method is not able to handle some specifics of
* configurations derived from AbstractConfiguration (e.g.
* list delimiters). For a full support of all of these features the
* copy() method of AbstractConfiguration should
* be used. In a future release this method might become deprecated.
*
* @param source the source configuration
* @param target the target configuration
* @since 1.1
*/
public static void append(Configuration source, Configuration target)
{
Iterator keys = source.getKeys();
while (keys.hasNext())
{
String key = (String) keys.next();
target.addProperty(key, source.getProperty(key));
}
}
/**
* Converts the passed in configuration to a hierarchical one. If the
* configuration is already hierarchical, it is directly returned. Otherwise
* all properties are copied into a new hierarchical configuration.
*
* @param conf the configuration to convert
* @return the new hierarchical configuration (the result is null if
* and only if the passed in configuration is null)
* @since 1.3
*/
public static HierarchicalConfiguration convertToHierarchical(
Configuration conf)
{
return convertToHierarchical(conf, null);
}
/**
* Converts the passed in Configuration object to a
* hierarchical one using the specified ExpressionEngine. This
* conversion works by adding the keys found in the configuration to a newly
* created hierarchical configuration. When adding new keys to a
* hierarchical configuration the keys are interpreted by its
* ExpressionEngine. If they contain special characters (e.g.
* brackets) that are treated in a special way by the default expression
* engine, it may be necessary using a specific engine that can deal with
* such characters. Otherwise null can be passed in for the
* ExpressionEngine; then the default expression engine is
* used. If the passed in configuration is already hierarchical, it is
* directly returned. (However, the ExpressionEngine is set if
* it is not null.) Otherwise all properties are copied into a new
* hierarchical configuration.
*
* @param conf the configuration to convert
* @param engine the ExpressionEngine for the hierarchical
* configuration or null for the default
* @return the new hierarchical configuration (the result is null if
* and only if the passed in configuration is null)
* @since 1.6
*/
public static HierarchicalConfiguration convertToHierarchical(
Configuration conf, ExpressionEngine engine)
{
if (conf == null)
{
return null;
}
if (conf instanceof HierarchicalConfiguration)
{
HierarchicalConfiguration hc = (HierarchicalConfiguration) conf;
if (engine != null)
{
hc.setExpressionEngine(engine);
}
return hc;
}
else
{
HierarchicalConfiguration hc = new HierarchicalConfiguration();
if (engine != null)
{
hc.setExpressionEngine(engine);
}
// Workaround for problem with copy()
boolean delimiterParsingStatus = hc.isDelimiterParsingDisabled();
hc.setDelimiterParsingDisabled(true);
hc.append(conf);
hc.setDelimiterParsingDisabled(delimiterParsingStatus);
return hc;
}
}
/**
* Clones the given configuration object if this is possible. If the passed
* in configuration object implements the Cloneable
* interface, its clone() method will be invoked. Otherwise
* an exception will be thrown.
*
* @param config the configuration object to be cloned (can be null)
* @return the cloned configuration (null if the argument was
* null, too)
* @throws ConfigurationRuntimeException if cloning is not supported for
* this object
* @since 1.3
*/
public static Configuration cloneConfiguration(Configuration config)
throws ConfigurationRuntimeException
{
if (config == null)
{
return null;
}
else
{
try
{
return (Configuration) clone(config);
}
catch (CloneNotSupportedException cnex)
{
throw new ConfigurationRuntimeException(cnex);
}
}
}
/**
* An internally used helper method for cloning objects. This implementation
* is not very sophisticated nor efficient. Maybe it can be replaced by an
* implementation from Commons Lang later. The method checks whether the
* passed in object implements the Cloneable interface. If
* this is the case, the clone() method is invoked by
* reflection. Errors that occur during the cloning process are re-thrown as
* runtime exceptions.
*
* @param obj the object to be cloned
* @return the cloned object
* @throws CloneNotSupportedException if the object cannot be cloned
*/
static Object clone(Object obj) throws CloneNotSupportedException
{
if (obj instanceof Cloneable)
{
try
{
Method m = obj.getClass().getMethod(METHOD_CLONE, null);
return m.invoke(obj, null);
}
catch (NoSuchMethodException nmex)
{
throw new CloneNotSupportedException(
"No clone() method found for class"
+ obj.getClass().getName());
}
catch (IllegalAccessException iaex)
{
throw new ConfigurationRuntimeException(iaex);
}
catch (InvocationTargetException itex)
{
throw new ConfigurationRuntimeException(itex);
}
}
else
{
throw new CloneNotSupportedException(obj.getClass().getName()
+ " does not implement Cloneable");
}
}
/**
* Constructs a URL from a base path and a file name. The file name can
* be absolute, relative or a full URL. If necessary the base path URL is
* applied.
*
* @param basePath the base path URL (can be null)
* @param file the file name
* @return the resulting URL
* @throws MalformedURLException if URLs are invalid
*/
public static URL getURL(String basePath, String file) throws MalformedURLException
{
File f = new File(file);
if (f.isAbsolute()) // already absolute?
{
return toURL(f);
}
try
{
if (basePath == null)
{
return new URL(file);
}
else
{
URL base = new URL(basePath);
return new URL(base, file);
}
}
catch (MalformedURLException uex)
{
return toURL(constructFile(basePath, file));
}
}
/**
* Helper method for constructing a file object from a base path and a
* file name. This method is called if the base path passed to
* getURL() does not seem to be a valid URL.
*
* @param basePath the base path
* @param fileName the file name
* @return the resulting file
*/
static File constructFile(String basePath, String fileName)
{
File file = null;
File absolute = null;
if (fileName != null)
{
absolute = new File(fileName);
}
if (StringUtils.isEmpty(basePath) || (absolute != null && absolute.isAbsolute()))
{
file = new File(fileName);
}
else
{
StringBuffer fName = new StringBuffer();
fName.append(basePath);
// My best friend. Paranoia.
if (!basePath.endsWith(File.separator))
{
fName.append(File.separator);
}
//
// We have a relative path, and we have
// two possible forms here. If we have the
// "./" form then just strip that off first
// before continuing.
//
if (fileName.startsWith("." + File.separator))
{
fName.append(fileName.substring(2));
}
else
{
fName.append(fileName);
}
file = new File(fName.toString());
}
return file;
}
/**
* Return the location of the specified resource by searching the user home
* directory, the current classpath and the system classpath.
*
* @param name the name of the resource
*
* @return the location of the resource
*/
public static URL locate(String name)
{
return locate(null, name);
}
/**
* Return the location of the specified resource by searching the user home
* directory, the current classpath and the system classpath.
*
* @param base the base path of the resource
* @param name the name of the resource
*
* @return the location of the resource
*/
public static URL locate(String base, String name)
{
if (log.isDebugEnabled())
{
StringBuffer buf = new StringBuffer();
buf.append("ConfigurationUtils.locate(): base is ").append(base);
buf.append(", name is ").append(name);
log.debug(buf.toString());
}
if (name == null)
{
// undefined, always return null
return null;
}
URL url = null;
// attempt to create an URL directly
try
{
if (base == null)
{
url = new URL(name);
}
else
{
URL baseURL = new URL(base);
url = new URL(baseURL, name);
// check if the file exists
InputStream in = null;
try
{
in = url.openStream();
}
finally
{
if (in != null)
{
in.close();
}
}
}
log.debug("Loading configuration from the URL " + url);
}
catch (IOException e)
{
url = null;
}
// attempt to load from an absolute path
if (url == null)
{
File file = new File(name);
if (file.isAbsolute() && file.exists()) // already absolute?
{
try
{
url = toURL(file);
log.debug("Loading configuration from the absolute path " + name);
}
catch (MalformedURLException e)
{
log.warn("Could not obtain URL from file", e);
}
}
}
// attempt to load from the base directory
if (url == null)
{
try
{
File file = constructFile(base, name);
if (file != null && file.exists())
{
url = toURL(file);
}
if (url != null)
{
log.debug("Loading configuration from the path " + file);
}
}
catch (MalformedURLException e)
{
log.warn("Could not obtain URL from file", e);
}
}
// attempt to load from the user home directory
if (url == null)
{
try
{
File file = constructFile(System.getProperty("user.home"), name);
if (file != null && file.exists())
{
url = toURL(file);
}
if (url != null)
{
log.debug("Loading configuration from the home path " + file);
}
}
catch (MalformedURLException e)
{
log.warn("Could not obtain URL from file", e);
}
}
// attempt to load from classpath
if (url == null)
{
url = locateFromClasspath(name);
}
return url;
}
/**
* Tries to find a resource with the given name in the classpath.
* @param resourceName the name of the resource
* @return the URL to the found resource or null if the resource
* cannot be found
*/
static URL locateFromClasspath(String resourceName)
{
URL url = null;
// attempt to load from the context classpath
ClassLoader loader = Thread.currentThread().getContextClassLoader();
if (loader != null)
{
url = loader.getResource(resourceName);
if (url != null)
{
log.debug("Loading configuration from the context classpath (" + resourceName + ")");
}
}
// attempt to load from the system classpath
if (url == null)
{
url = ClassLoader.getSystemResource(resourceName);
if (url != null)
{
log.debug("Loading configuration from the system classpath (" + resourceName + ")");
}
}
return url;
}
/**
* Return the path without the file name, for example http://xyz.net/foo/bar.xml
* results in http://xyz.net/foo/
*
* @param url the URL from which to extract the path
* @return the path component of the passed in URL
*/
static String getBasePath(URL url)
{
if (url == null)
{
return null;
}
String s = url.toString();
if (s.endsWith("/") || StringUtils.isEmpty(url.getPath()))
{
return s;
}
else
{
return s.substring(0, s.lastIndexOf("/") + 1);
}
}
/**
* Extract the file name from the specified URL.
*
* @param url the URL from which to extract the file name
* @return the extracted file name
*/
static String getFileName(URL url)
{
if (url == null)
{
return null;
}
String path = url.getPath();
if (path.endsWith("/") || StringUtils.isEmpty(path))
{
return null;
}
else
{
return path.substring(path.lastIndexOf("/") + 1);
}
}
/**
* Tries to convert the specified base path and file name into a file object.
* This method is called e.g. by the save() methods of file based
* configurations. The parameter strings can be relative files, absolute
* files and URLs as well. This implementation checks first whether the passed in
* file name is absolute. If this is the case, it is returned. Otherwise
* further checks are performed whether the base path and file name can be
* combined to a valid URL or a valid file name. Note: The test
* if the passed in file name is absolute is performed using
* java.io.File.isAbsolute(). If the file name starts with a
* slash, this method will return true on Unix, but false on
* Windows. So to ensure correct behavior for relative file names on all
* platforms you should never let relative paths start with a slash. E.g.
* in a configuration definition file do not use something like that:
*
* <properties fileName="/subdir/my.properties"/>
*
* Under Windows this path would be resolved relative to the configuration
* definition file. Under Unix this would be treated as an absolute path
* name.
*
* @param basePath the base path
* @param fileName the file name
* @return the file object (null if no file can be obtained)
*/
public static File getFile(String basePath, String fileName)
{
// Check if the file name is absolute
File f = new File(fileName);
if (f.isAbsolute())
{
return f;
}
// Check if URLs are involved
URL url;
try
{
url = new URL(new URL(basePath), fileName);
}
catch (MalformedURLException mex1)
{
try
{
url = new URL(fileName);
}
catch (MalformedURLException mex2)
{
url = null;
}
}
if (url != null)
{
return fileFromURL(url);
}
return constructFile(basePath, fileName);
}
/**
* Tries to convert the specified URL to a file object. If this fails,
* null is returned.
*
* @param url the URL
* @return the resulting file object
*/
public static File fileFromURL(URL url)
{
if (PROTOCOL_FILE.equals(url.getProtocol()))
{
return new File(URLDecoder.decode(url.getPath()));
}
else
{
return null;
}
}
/**
* Convert the specified file into an URL. This method is equivalent
* to file.toURI().toURL() on Java 1.4 and above, and equivalent to
* file.toURL() on Java 1.3. This is to work around a bug in the JDK
* preventing the transformation of a file into an URL if the file name
* contains a '#' character. See the issue CONFIGURATION-300 for
* more details.
*
* @param file the file to be converted into an URL
*/
static URL toURL(File file) throws MalformedURLException
{
if (SystemUtils.isJavaVersionAtLeast(JAVA_1_4))
{
try
{
Method toURI = file.getClass().getMethod("toURI", (Class[]) null);
Object uri = toURI.invoke(file, (Class[]) null);
Method toURL = uri.getClass().getMethod("toURL", (Class[]) null);
URL url = (URL) toURL.invoke(uri, (Class[]) null);
return url;
}
catch (Exception e)
{
throw new MalformedURLException(e.getMessage());
}
}
else
{
return file.toURL();
}
}
/**
* Enables runtime exceptions for the specified configuration object. This
* method can be used for configuration implementations that may face errors
* on normal property access, e.g. DatabaseConfiguration or
* JNDIConfiguration. Per default such errors are simply
* logged and then ignored. This implementation will register a special
* {@link ConfigurationErrorListener} that throws a runtime
* exception (namely a ConfigurationRuntimeException) on
* each received error event.
*
* @param src the configuration, for which runtime exceptions are to be
* enabled; this configuration must be derived from
* {@link EventSource}
*/
public static void enableRuntimeExceptions(Configuration src)
{
if (!(src instanceof EventSource))
{
throw new IllegalArgumentException(
"Configuration must be derived from EventSource!");
}
((EventSource) src).addErrorListener(new ConfigurationErrorListener()
{
public void configurationError(ConfigurationErrorEvent event)
{
// Throw a runtime exception
throw new ConfigurationRuntimeException(event.getCause());
}
});
}
}
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