org.keycloak.common.util.StringPropertyReplacer Maven / Gradle / Ivy
/*
* Copyright 2016 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* 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.
*/
package org.keycloak.common.util;
import java.io.File;
import java.util.Properties;
/**
* A utility class for replacing properties in strings.
*
* @author Jason Dillon
* @author Scott Stark
* @author Claudio Vesco
* @author Adrian Brock
* @author Dimitris Andreadis
* @version $Revision: 2898 $
*/
public final class StringPropertyReplacer
{
/** New line string constant */
public static final String NEWLINE = System.getProperty("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;
private static final Properties systemEnvProperties = new SystemEnvProperties();
/**
* Go through the input string and replace any occurrence of ${p} with
* the System.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 System.getProperty("file.separator")
* value and the property ${:} is replaced with System.getProperty("path.separator").
*
* @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, (Properties) null);
}
/**
* Go through the input string and replace any occurrence of ${p} with
* the props.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 System.getProperty("file.separator")
* value and the property ${:} is replaced with System.getProperty("path.separator").
*
* @param string - the string with possible ${} references
* @param props - the source for ${x} property ref values, null means use System.getProperty()
* @return the input string with all property references replaced if any.
* If there are no valid references the input string will be returned.
*/
public static String replaceProperties(final String string, final Properties props) {
if (props == null) {
return replaceProperties(string, (PropertyResolver) null);
}
return replaceProperties(string, props::getProperty);
}
public static String replaceProperties(final String string, PropertyResolver resolver)
{
if(string == null) {
return null;
}
final char[] chars = string.toCharArray();
StringBuilder buffer = new StringBuilder();
boolean properties = false;
int state = NORMAL;
int start = 0;
int openBracketsCount = 0;
for (int i = 0; i < chars.length; ++i)
{
char c = chars[i];
// Dollar sign outside brackets
if (c == '$' && state != IN_BRACKET)
state = SEEN_DOLLAR;
// Open bracket immediately after dollar
else if (c == '{' && state == SEEN_DOLLAR)
{
buffer.append(string.substring(start, i - 1));
state = IN_BRACKET;
start = i - 1;
openBracketsCount = 1;
}
// Seeing open bracket after we already saw some open bracket without corresponding closed bracket. This causes "nested" expressions. For example ${foo:${bar}}
else if (c == '{' && state == IN_BRACKET)
openBracketsCount++;
// No open bracket after dollar
else if (state == SEEN_DOLLAR)
state = NORMAL;
// Seeing closed bracket, but we already saw more than one open bracket before. Hence "nested" expression is still not fully closed.
// For example expression ${foo:${bar}} is closed after the second closed bracket, not after the first closed bracket.
else if (c == '}' && state == IN_BRACKET && openBracketsCount > 1)
openBracketsCount--;
// 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
{
// check from the properties
if (resolver != null)
value = resolver.resolve(key);
else
value = systemEnvProperties.getProperty(key);
if (value == null)
{
// Check for a default value ${key:default}
int colon = key.indexOf(':');
if (colon > 0)
{
String realKey = key.substring(0, colon);
if (resolver != null)
value = resolver.resolve(realKey);
else
value = systemEnvProperties.getProperty(realKey);
if (value == null)
{
// Check for a composite key, "key1,key2"
value = resolveCompositeKey(realKey, resolver);
// Not a composite key either, use the specified default
if (value == null)
value = key.substring(colon+1);
}
}
else
{
// No default, check for a composite key, "key1,key2"
value = resolveCompositeKey(key, resolver);
}
}
}
if (value != null)
{
properties = true;
buffer.append(value);
}
else
{
buffer.append("${");
buffer.append(key);
buffer.append('}');
}
}
start = i + 1;
state = NORMAL;
}
}
// No properties
if (!properties)
return string;
// Collect the trailing characters
if (start != chars.length)
buffer.append(string.substring(start, chars.length));
if (buffer.indexOf("${") != -1) {
try {
return replaceProperties(buffer.toString(), resolver);
} catch (StackOverflowError ex) {
throw new IllegalStateException("Infinite recursion happening when replacing properties on '" + buffer + "'");
}
}
// Done
return buffer.toString();
}
private static String resolveCompositeKey(String key, PropertyResolver resolver)
{
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);
if (resolver != null)
value = resolver.resolve(key1);
else
value = systemEnvProperties.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);
if (resolver != null)
value = resolver.resolve(key2);
else
value = systemEnvProperties.getProperty(key2);
}
}
// Return whatever we've found or null
return value;
}
public interface PropertyResolver {
String resolve(String property);
}
}
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