/*
* Copyright (c) 2010-2013 the original author or authors
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
package org.jmxtrans.embedded.util.json;
import org.jmxtrans.embedded.EmbeddedJmxTransException;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.io.Serializable;
/**
* Inspired by Spring Property placeholder mechanism.
* <p/>
* Placeholders are delimited by '{' and '}' and support default value with ':'. Sample : '<code>{graphite.host}</code>'
* or '<code>{graphite.port:2003}</code>'.
* <p/>
* If the placeholder is not found in the system properties, it is searched in the environment variables and then
* converted to underscore delimited upper case and searched in environment variables.
* <p/>
* Sample for '<code>{graphite.port:2003}</code>':
* <ol>
* <li><code>System.getProperty("graphite.port")</code></li>
* <li><code>System.getenv("graphite.port")</code></li>
* <li><code>System.getenv("GRAPHITE_PORT")</code></li>
* <li>default to <code>2003</code></li>
* </ol>
*
* @author <a href="mailto:cleclerc@xebia.fr">Cyrille Le Clerc</a>
*/
public class PropertyPlaceholderResolver implements Serializable {
private static final long serialVersionUID = 1L;
/**
* Parse the given <code>string</code> resolving property placeholders (<code>${my-property[:default-value]}</code>)
*
* @param string the string to parse.
* @return the parsed string.
* @throws org.jmxtrans.embedded.EmbeddedJmxTransException a property placeholder could not be resolved and no default value has been defined.
*/
@Nonnull
public String resolveString(@Nonnull String string) throws EmbeddedJmxTransException {
StringBuilder result = new StringBuilder(string.length());
int position = 0;
while (position < string.length()) {
char c = string.charAt(position);
if (c == '$' && (position < string.length() - 1) && string.charAt(position + 1) == '{') {
int beginningBracketPosition = position + 1;
int endingBracketPosition = string.indexOf('}', beginningBracketPosition);
int colonPosition = string.indexOf(':', beginningBracketPosition);
if (colonPosition > endingBracketPosition) {
colonPosition = -1;
}
String placeholder;
String defaultValue;
if (colonPosition == -1) {
placeholder = string.substring(beginningBracketPosition + 1, endingBracketPosition);
defaultValue = null;
} else {
placeholder = string.substring(beginningBracketPosition + 1, colonPosition);
defaultValue = string.substring(colonPosition + 1, endingBracketPosition);
}
String resolvedPlaceHolder = resolvePlaceholder(placeholder, defaultValue);
result.append(resolvedPlaceHolder);
position = endingBracketPosition + 1;
} else {
result.append(c);
position++;
}
}
return result.toString();
}
/**
* Search for the given placeholder in system properties then in environment variables.
*
* @param property property to resolve
* @param defaultValue Default value if the placeholder is not found. <code>null</code> means not default value is
* defined and the placeholder must exist
* @return the resolved property or the default value if the placeholder is not found and the default value is defined
* @throws org.jmxtrans.embedded.EmbeddedJmxTransException if the placeholder is not found and the given <code>defaultValue</code> is not
* defined (<code>null</code>)
*/
@Nonnull
protected String resolvePlaceholder(String property, @Nullable String defaultValue) throws EmbeddedJmxTransException {
// "graphite.host" -> "GRAPHITE_HOST"
String environmentVariableStyleProperty = property.toUpperCase();
environmentVariableStyleProperty = environmentVariableStyleProperty.replaceAll("\\.", "_");
String result;
if (System.getProperties().containsKey(property)) {
result = System.getProperty(property);
} else if (System.getenv().containsKey(property)) {
result = System.getenv(property);
} else if (System.getenv().containsKey(environmentVariableStyleProperty)) {
result = System.getenv(environmentVariableStyleProperty);
} else if (defaultValue != null) {
result = defaultValue;
} else {
throw new EmbeddedJmxTransException("Property '" + property + "' not found in System properties nor in Environment variables");
}
return result;
}
}