/*
* #%L
* Gravia :: Resource
* %%
* Copyright (C) 2010 - 2014 JBoss by Red Hat
* %%
* Licensed 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.
* #L%
*/
package org.jboss.gravia.utils;
import java.io.File;
/**
* A utility class for replacing properties in strings.
*
* @author Thomas.Diesler@jboss.com
* @since 16-Sep-2010
*/
public final class StringPropertyReplacer {
/** New line string constant */
public static final String NEWLINE = SecurityActions.getSystemProperty("line.separator", "\n");
/** File separator value */
private static final String FILE_SEPARATOR = File.separator;
/** Path separator value */
private static final String PATH_SEPARATOR = File.pathSeparator;
/** File separator alias */
private static final String FILE_SEPARATOR_ALIAS = "/";
/** Path separator alias */
private static final String PATH_SEPARATOR_ALIAS = ":";
// States used in property parsing
private static final int NORMAL = 0;
private static final int SEEN_DOLLAR = 1;
private static final int IN_BRACKET = 2;
public interface PropertyProvider {
String getProperty(String key);
}
/**
* Go through the input string and replace any occurance of ${p} with the System.getProperty(p) value. If there is no such
* property p defined, then the ${p} reference will remain unchanged.
*
* @param string - the string with possible ${} references
* @return the input string with all property references replaced if any. If there are no valid references the input string
* will be returned.
*/
public static String replaceProperties(final String string) {
return replaceProperties(string, new PropertyProvider() {
@Override
public String getProperty(String key) {
return System.getProperty(key);
}
});
}
/**
* Go through the input string and replace any occurance of ${p} with the PropertyProvider.getProperty(p) value. If there is
* no such property p defined, then the ${p} reference will remain unchanged.
*
* If the property reference is of the form ${p:v} and there is no such property p, then the default value v will be
* returned.
*
* If the property reference is of the form ${p1,p2} or ${p1,p2:v} then the primary and the secondary properties will be
* tried in turn, before returning either the unchanged input, or the default value.
*
* The property ${/} is replaced with PropertyProvider.getProperty("file.separator") value and the property ${:} is replaced
* with PropertyProvider.getProperty("path.separator").
*
* @param string - the string with possible ${} references
* @param provider - the source for ${x} property ref values
* @return the input string with all property references replaced if any. If there are no valid references the input string
* will be returned.
*/
public static String replaceProperties(String string, PropertyProvider provider) {
IllegalArgumentAssertion.assertNotNull(string, "string");
IllegalArgumentAssertion.assertNotNull(provider, "provider");
final char[] chars = string.toCharArray();
StringBuffer buffer = new StringBuffer();
boolean properties = false;
int state = NORMAL;
int start = 0;
for (int i = 0; i < chars.length; ++i) {
char c = chars[i];
// Dollar sign outside brackets
if (c == '$' && state != IN_BRACKET)
state = SEEN_DOLLAR;
// Open bracket immediatley after dollar
else if (c == '{' && state == SEEN_DOLLAR) {
buffer.append(string.substring(start, i - 1));
state = IN_BRACKET;
start = i - 1;
}
// No open bracket after dollar
else if (state == SEEN_DOLLAR)
state = NORMAL;
// Closed bracket after open bracket
else if (c == '}' && state == IN_BRACKET) {
// No content
if (start + 2 == i) {
buffer.append("${}"); // REVIEW: Correct?
} else
// Collect the system property
{
String value = null;
String key = string.substring(start + 2, i);
// check for alias
if (FILE_SEPARATOR_ALIAS.equals(key)) {
value = FILE_SEPARATOR;
} else if (PATH_SEPARATOR_ALIAS.equals(key)) {
value = PATH_SEPARATOR;
} else {
value = provider.getProperty(key);
if (value == null) {
// Check for a default value ${key:default}
int colon = key.indexOf(':');
if (colon > 0) {
String realKey = key.substring(0, colon);
value = provider.getProperty(key);
if (value == null) {
// Check for a composite key, "key1,key2"
value = resolveCompositeKey(realKey, provider);
// Not a composite key either, use the specified default
if (value == null)
value = key.substring(colon + 1);
}
} else {
// No default, check for a composite key, "key1,key2"
value = resolveCompositeKey(key, provider);
}
}
}
if (value != null) {
properties = true;
buffer.append(value);
} else {
buffer.append("${");
buffer.append(key);
buffer.append('}');
}
}
start = i + 1;
state = NORMAL;
}
}
// No properties
if (properties == false)
return string;
// Collect the trailing characters
if (start != chars.length)
buffer.append(string.substring(start, chars.length));
// Done
return buffer.toString();
}
/**
* Try to resolve a "key" from the provided properties by checking if it is actually a "key1,key2", in which case try first
* "key1", then "key2". If all fails, return null.
*
* It also accepts "key1," and ",key2".
*
* @param key the key to resolve
* @param props the properties to use
* @return the resolved key or null
*/
private static String resolveCompositeKey(String key, PropertyProvider provider) {
String value = null;
// Look for the comma
int comma = key.indexOf(',');
if (comma > -1) {
// If we have a first part, try resolve it
if (comma > 0) {
// Check the first part
String key1 = key.substring(0, comma);
value = provider.getProperty(key1);
}
// Check the second part, if there is one and first lookup failed
if (value == null && comma < key.length() - 1) {
String key2 = key.substring(comma + 1);
value = provider.getProperty(key2);
}
}
// Return whatever we've found or null
return value;
}
}