io.rxmicro.common.util.Environments Maven / Gradle / Ivy
Show all versions of rxmicro-common Show documentation
/*
* Copyright (c) 2020. https://rxmicro.io
*
* 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 io.rxmicro.common.util;
import io.rxmicro.common.model.StringIterator;
import java.util.Locale;
import java.util.Map;
import static io.rxmicro.common.util.Formats.format;
import static java.lang.System.getProperty;
/**
* Environment utility class.
*
* @author nedis
* @see System#getProperty(String)
* @since 0.1
*/
public final class Environments {
private static final String OS_NAME = "os.name";
private static final String UNKNOWN = "unknown";
/**
* Returns {@code true} if current OS is macOS.
*
* @return {@code true} if current OS is macOS.
*/
public static boolean isCurrentOsMac() {
return getProperty(OS_NAME, UNKNOWN).toLowerCase(Locale.ENGLISH).contains("mac");
}
/**
* Returns {@code true} if current OS is Linux.
*
* @return {@code true} if current OS is Linux.
*/
public static boolean isCurrentOsLinux() {
return getProperty(OS_NAME, UNKNOWN).toLowerCase(Locale.ENGLISH).contains("linux");
}
/**
* Returns {@code true} if current OS is Windows.
*
* @return {@code true} if current OS is Windows.
*/
public static boolean isCurrentOsWindows() {
return getProperty(OS_NAME, UNKNOWN).toLowerCase(Locale.ENGLISH).contains("windows");
}
/**
* Finds variables in the specified expression and replaces found variables by the configured environment variables.
*
*
* Supported variable format: ${VAR1}
*
* @param expression the specified expression that can contains variables
* @return the resolved expression without variables
* @see System#getenv()
* @since 0.6
* @throws IllegalArgumentException if the specified expression contains undefined variable or has invalid syntax
*/
public static String resolveEnvironmentVariables(final String expression) {
return resolveVariables(expression, System.getenv());
}
/**
* Finds variables in the specified expression and replaces found variables by the provided values.
*
*
* Supported variable format: ${VAR1}
*
* @param expression the specified expression that can contains variables
* @param variableValues the variable map that contains the pairs of names nad values
* @return the resolved expression without variables
* @since 0.6
* @throws IllegalArgumentException if the specified expression contains undefined variable or has invalid syntax
*/
public static String resolveVariables(final String expression,
final Map variableValues) {
final StringBuilder stringBuilder = new StringBuilder(expression.length());
final StringIterator iterator = new StringIterator(expression);
resolve(variableValues, stringBuilder, iterator);
return stringBuilder.toString();
}
private static void resolve(final Map variableValues,
final StringBuilder stringBuilder,
final StringIterator iterator) {
while (iterator.next()) {
final char ch = iterator.getCurrent();
if ('$' == ch) {
final String variableName = readVariableName(iterator);
final String value = variableValues.get(variableName);
if (value == null) {
throw new IllegalArgumentException(format(
"Invalid expression: '?'. Variable '?' not defined!",
iterator.getSource(), variableName
));
} else {
stringBuilder.append(value);
}
} else if ('{' == ch || '}' == ch) {
throw new IllegalArgumentException(format(
"Invalid expression: '?'. Missing '$' at ? position",
iterator.getSource(), iterator.getIndex()
));
} else {
stringBuilder.append(ch);
}
}
}
private static String readVariableName(final StringIterator iterator) {
if (iterator.next()) {
final char ch = iterator.getCurrent();
if ('{' == ch) {
final int start = iterator.getIndex() + 1;
while (iterator.next()) {
if ('}' == iterator.getCurrent()) {
final int end = iterator.getIndex();
if (end > start) {
return iterator.getSource().substring(start, end);
} else {
throw new IllegalArgumentException(format(
"Invalid expression: '?'. Missing variable name at ? position!",
iterator.getSource(), end
));
}
}
}
throw new IllegalArgumentException(format(
"Invalid expression: '?'. Missing '}'",
iterator.getSource()
));
}
}
throw new IllegalArgumentException(format(
"Invalid expression: '?'. Expected '{' after '$' at ? position!",
iterator.getSource(), iterator.getIndex()
));
}
private Environments() {
}
}