org.apache.logging.log4j.util.PropertySource 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.logging.log4j.util;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* A source for global configuration properties.
*
* @since 2.10.0
*/
public interface PropertySource {
/**
* Returns the order in which this PropertySource has priority. A higher value means that the source will be
* applied later so as to take precedence over other property sources.
*
* @return priority value
*/
int getPriority();
/**
* Iterates over all properties and performs an action for each key/value pair.
*
* @param action action to perform on each key/value pair
*/
default void forEach(BiConsumer action) {
}
/**
* Converts a list of property name tokens into a normal form. For example, a list of tokens such as
* "foo", "bar", "baz", might be normalized into the property name "log4j2.fooBarBaz".
*
* @param tokens list of property name tokens
* @return a normalized property name using the given tokens
*/
default CharSequence getNormalForm(Iterable tokens) {
return null;
}
/**
* For PropertySources that cannot iterate over all the potential properties this provides a direct lookup.
* @param key The key to search for.
* @return The value or null;
* @since 2.13.0
*/
default String getProperty(String key) {
return null;
}
/**
* For PropertySources that cannot iterate over all the potential properties this provides a direct lookup.
* @param key The key to search for.
* @return The value or null;
* @since 2.13.0
*/
default boolean containsProperty(String key) {
return false;
}
/**
* Comparator for ordering PropertySource instances by priority.
*
* @since 2.10.0
*/
class Comparator implements java.util.Comparator, Serializable {
private static final long serialVersionUID = 1L;
@Override
public int compare(final PropertySource o1, final PropertySource o2) {
return Integer.compare(Objects.requireNonNull(o1).getPriority(), Objects.requireNonNull(o2).getPriority());
}
}
/**
* Utility methods useful for PropertySource implementations.
*
* @since 2.10.0
*/
final class Util {
private static final String PREFIXES = "(?i:^log4j2?[-._/]?|^org\\.apache\\.logging\\.log4j\\.)?";
private static final Pattern PROPERTY_TOKENIZER = Pattern.compile(PREFIXES + "([A-Z]*[a-z0-9]+|[A-Z0-9]+)[-._/]?");
private static final Map> CACHE = new ConcurrentHashMap<>();
/**
* Converts a property name string into a list of tokens. This will strip a prefix of {@code log4j},
* {@code log4j2}, {@code Log4j}, or {@code org.apache.logging.log4j}, along with separators of
* dash {@code -}, dot {@code .}, underscore {@code _}, and slash {@code /}. Tokens can also be separated
* by camel case conventions without needing a separator character in between.
*
* @param value property name
* @return the property broken into lower case tokens
*/
public static List tokenize(final CharSequence value) {
if (CACHE.containsKey(value)) {
return CACHE.get(value);
}
final List tokens = new ArrayList<>();
final Matcher matcher = PROPERTY_TOKENIZER.matcher(value);
while (matcher.find()) {
tokens.add(matcher.group(1).toLowerCase());
}
CACHE.put(value, tokens);
return tokens;
}
/**
* Joins a list of strings using camelCaseConventions.
*
* @param tokens tokens to convert
* @return tokensAsCamelCase
*/
public static CharSequence joinAsCamelCase(final Iterable tokens) {
final StringBuilder sb = new StringBuilder();
boolean first = true;
for (final CharSequence token : tokens) {
if (first) {
sb.append(token);
} else {
sb.append(Character.toUpperCase(token.charAt(0)));
if (token.length() > 1) {
sb.append(token.subSequence(1, token.length()));
}
}
first = false;
}
return sb.toString();
}
private Util() {
}
}
}