com.samskivert.util.Config Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of samskivert Show documentation
Show all versions of samskivert Show documentation
A collection of Java utilities.
//
// samskivert library - useful routines for java programs
// Copyright (C) 2001-2012 Michael Bayne, et al.
// http://github.com/samskivert/samskivert/blob/master/COPYING
package com.samskivert.util;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Properties;
import static com.samskivert.util.UtilLog.log;
/**
* The config class provides a unified interaface to application configuration information. See
* {@link PrefsConfig} for an extension of Config that allows the default values to be reconfigured
* and saved persistently.
*
* A common pattern is to create, for each package that shares configuration information, a
* singleton class containing a config object that is configured to load its data from a single
* configuration file. For example:
*
*
{@code
* public class FooConfig {
* public static final String FIDDLES = "fiddles";
* public static Config config = new Config("com/fribitz/foo");
* }
* }
*
* which would look for com/fribitz/foo.properties in the classpath and serve up those
* configuration values when requests were made from FooConfig.config. For example:
*
* {@code
* int fiddles = FooConfig.config.getValue(FooConfig.FIDDLES, 0);
* for (int ii = 0; ii < fiddles; ii++) {
* fiddle();
* }
* }
*
* An even better approach involves creating accessors for all defined configuration properties:
*
* {@code
* public class FooConfig {
* public static final String FIDDLES = "fiddles";
* public static Config config = new Config("com/fribitz/foo");
* public static int getFiddles () {
* return config.getValue(FIDDLES, FIDDLES_DEFAULT);
* }
* protected static final int FIDDLES_DEFAULT = 0;
* }
* }
*
* This allows the default value for fiddles to be specified in one place and
* simplifies life for the caller who can now simply request FooConfig.getFiddles().
*
* @see PrefsConfig
*/
public class Config
{
/**
* Constructs a new config object which will obtain configuration information from the
* specified properties bundle.
*/
public Config (String path)
{
_props = loadProperties(path, getClass().getClassLoader(), new Properties());
}
/**
* Constructs a new config object which will obtain configuration information from the
* specified properties bundle.
*
* @param loader the classloader to use to locate the properties file.
*/
public Config (String path, ClassLoader loader)
{
_props = loadProperties(path, loader, new Properties());
}
/**
* Constructs a config object which will obtain information from the supplied properties.
*/
public Config (Properties props)
{
_props = props;
}
@Deprecated
public Config (String path, Properties props)
{
this(props);
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not and integer, not in proper
* array specification), a warning message will be logged and the default value will be
* returned.
*
* @param name name of the property.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public int getValue (String name, int defval)
{
String val = _props.getProperty(name);
if (val != null) {
try {
return Integer.decode(val).intValue(); // handles base 10, hex values, etc.
} catch (NumberFormatException nfe) {
log.warning("Malformed integer property", "name", name, "value", val);
}
}
return defval;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not and integer, not in proper
* array specification), a warning message will be logged and the default value will be
* returned.
*
* @param name name of the property.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public long getValue (String name, long defval)
{
String val = _props.getProperty(name);
if (val != null) {
try {
defval = Long.parseLong(val);
} catch (NumberFormatException nfe) {
log.warning("Malformed long integer property", "name", name, "value", val);
}
}
return defval;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not and integer, not in proper
* array specification), a warning message will be logged and the default value will be
* returned.
*
* @param name name of the property.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public float getValue (String name, float defval)
{
String val = _props.getProperty(name);
if (val != null) {
try {
defval = Float.parseFloat(val);
} catch (NumberFormatException nfe) {
log.warning("Malformed float property", "name", name, "value", val);
}
}
return defval;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* The returned value will be false if the config value is "false"
* (case-insensitive), else the return value will be true.
*
* @param name the name of the property to be fetched.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public boolean getValue (String name, boolean defval)
{
String val = _props.getProperty(name);
if (val != null) {
defval = !val.equalsIgnoreCase("false");
}
return defval;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
*
* @param name the name of the property to be fetched.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public String getValue (String name, String defval)
{
return _props.getProperty(name, defval);
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not and integer, not in proper
* array specification), a warning message will be logged and the default value will be
* returned.
*
* @param name the name of the property to be fetched.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public int[] getValue (String name, int[] defval)
{
// look up the value in the configuration file and use that to look up any overridden value
String val = getValue(name, (String)null);
int[] result = defval;
// parse it into an array of ints
if (val != null) {
result = StringUtil.parseIntArray(val);
if (result == null) {
log.warning("Malformed int array property", "name", name, "value", val);
return defval;
}
}
return result;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not and integer, not in proper
* array specification), a warning message will be logged and the default value will be
* returned.
*
* @param name the name of the property to be fetched.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public long[] getValue (String name, long[] defval)
{
// look up the value in the configuration file and use that to look up any overridden value
String val = getValue(name, (String)null);
long[] result = defval;
// parse it into an array of longs
if (val != null) {
result = StringUtil.parseLongArray(val);
if (result == null) {
log.warning("Malformed int array property", "name", name, "value", val);
return defval;
}
}
return result;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not a floating point value, not
* in proper array specification), a warning message will be logged and the default value will
* be returned.
*
* @param name the name of the property to be fetched.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public float[] getValue (String name, float[] defval)
{
// look up the value in the configuration file and use that to look up any overridden value
String val = getValue(name, (String)null);
float[] result = defval;
// parse it into an array of ints
if (val != null) {
result = StringUtil.parseFloatArray(val);
if (result == null) {
log.warning("Malformed int array property", "name", name, "value", val);
return defval;
}
}
return result;
}
/**
* Fetches and returns the value for the specified configuration property. If the value is not
* specified in the associated properties file, the supplied default value is returned instead.
* If the property specified in the file is poorly formatted (not and integer, not in proper
* array specification), a warning message will be logged and the default value will be
* returned.
*
* @param name the name of the property to be fetched.
* @param defval the value to return if the property is not specified in the config file.
*
* @return the value of the requested property.
*/
public String[] getValue (String name, String[] defval)
{
// look up the value in the configuration file and use that to look up any overridden value
String val = getValue(name, (String)null);
String[] result = defval;
// parse it into an array of ints
if (val != null) {
result = StringUtil.parseStringArray(val);
if (result == null) {
log.warning("Malformed string array property", "name", name, "value", val);
return defval;
}
}
return result;
}
/**
* Looks up the specified string-valued configuration entry, loads the class with that name and
* instantiates a new instance of that class, which is returned.
*
* @param name the name of the property to be fetched.
* @param defcname the class name to use if the property is not specified in the config file.
*
* @exception Exception thrown if any error occurs while loading or instantiating the class.
*/
public Object instantiateValue (String name, String defcname)
throws Exception
{
return Class.forName(getValue(name, defcname)).newInstance();
}
/**
* Returns a properties object containing all configuration values that start with the supplied
* prefix (plus a trailing "." which will be added if it doesn't already exist). The keys in
* the sub-properties will have had the prefix stripped off.
*/
public Properties getSubProperties (String prefix)
{
Properties props = new Properties();
getSubProperties(prefix, props);
return props;
}
/**
* Fills into the supplied properties object all configuration values that start with the
* supplied prefix (plus a trailing "." which will be added if it doesn't already exist). The
* keys in the sub-properties will have had the prefix stripped off.
*/
public void getSubProperties (String prefix, Properties target)
{
// slap a trailing dot on if necessary
if (!prefix.endsWith(".")) {
prefix = prefix + ".";
}
// build the sub-properties
for (Iterator iter = keys(); iter.hasNext(); ) {
String key = iter.next();
if (!key.startsWith(prefix)) {
continue;
}
String value = getValue(key, (String)null);
if (value == null) {
continue;
}
target.put(key.substring(prefix.length()), value);
}
}
/**
* Returns an iterator that returns all of the configuration keys in this config object.
*/
public Iterator keys ()
{
HashSet matches = new HashSet();
enumerateKeys(matches);
return matches.iterator();
}
protected static Properties loadProperties (String path, ClassLoader loader, Properties props)
{
try {
ConfigUtil.loadProperties(path + PROPS_SUFFIX, loader, props);
} catch (FileNotFoundException fnfe) {
log.debug("No properties file found to back config", "path", path);
} catch (IOException ioe) {
log.warning("Unable to load configuration", "path", path, "ioe", ioe);
}
return props;
}
protected void enumerateKeys (HashSet keys)
{
Enumeration defkeys = _props.propertyNames();
while (defkeys.hasMoreElements()) {
keys.add((String)defkeys.nextElement());
}
}
/** Contains the default configuration information. */
protected Properties _props;
/** The file extension used for configuration files. */
protected static final String PROPS_SUFFIX = ".properties";
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy