org.springframework.util.SystemPropertyUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2006 the original author or authors.
*
* 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.springframework.util;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Helper class for resolving placeholders in texts. Usually applied to file paths.
*
* A text may contain ${...} placeholders, to be resolved as
* system properties: e.g. ${user.dir}.
*
* @author Juergen Hoeller
* @since 1.2.5
* @see #PLACEHOLDER_PREFIX
* @see #PLACEHOLDER_SUFFIX
* @see System#getProperty(String)
*/
public abstract class SystemPropertyUtils {
/** Prefix for system property placeholders: "${" */
public static final String PLACEHOLDER_PREFIX = "${";
/** Suffix for system property placeholders: "}" */
public static final String PLACEHOLDER_SUFFIX = "}";
private static final Log logger = LogFactory.getLog(SystemPropertyUtils.class);
/**
* Resolve ${...} placeholders in the given text,
* replacing them with corresponding system property values.
* @param text the String to resolve
* @return the resolved String
* @see #PLACEHOLDER_PREFIX
* @see #PLACEHOLDER_SUFFIX
*/
public static String resolvePlaceholders(String text) {
StringBuffer buf = new StringBuffer(text);
// The following code does not use JDK 1.4's StringBuffer.indexOf(String)
// method to retain JDK 1.3 compatibility. The slight loss in performance
// is not really relevant, as this code will typically just run on startup.
int startIndex = text.indexOf(PLACEHOLDER_PREFIX);
while (startIndex != -1) {
int endIndex = buf.toString().indexOf(PLACEHOLDER_SUFFIX, startIndex + PLACEHOLDER_PREFIX.length());
if (endIndex != -1) {
String placeholder = buf.substring(startIndex + PLACEHOLDER_PREFIX.length(), endIndex);
int nextIndex = endIndex + PLACEHOLDER_SUFFIX.length();
try {
String propVal = System.getProperty(placeholder);
if (propVal == null) {
// Fall back to searching the system environment.
propVal = System.getenv(placeholder);
}
if (propVal != null) {
buf.replace(startIndex, endIndex + PLACEHOLDER_SUFFIX.length(), propVal);
nextIndex = startIndex + propVal.length();
}
else {
if (logger.isWarnEnabled()) {
logger.warn("Could not resolve placeholder '" + placeholder + "' in [" + text +
"] as system property: neither system property nor environment variable found");
}
}
}
catch (Throwable ex) {
if (logger.isWarnEnabled()) {
logger.warn("Could not resolve placeholder '" + placeholder + "' in [" + text +
"] as system property: " + ex);
}
}
startIndex = buf.toString().indexOf(PLACEHOLDER_PREFIX, nextIndex);
}
else {
startIndex = -1;
}
}
return buf.toString();
}
}