001/*
002 * Copyright 2012-2017 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.boot.context;
018
019import org.apache.commons.logging.Log;
020import org.apache.commons.logging.LogFactory;
021
022import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
023import org.springframework.context.ApplicationListener;
024import org.springframework.core.Ordered;
025import org.springframework.core.env.ConfigurableEnvironment;
026
027/**
028 * An {@link ApplicationListener} that halts application startup if the system file
029 * encoding does not match an expected value set in the environment. By default has no
030 * effect, but if you set {@code spring.mandatory_file_encoding} (or some camelCase or
031 * UPPERCASE variant of that) to the name of a character encoding (e.g. "UTF-8") then this
032 * initializer throws an exception when the {@code file.encoding} System property does not
033 * equal it.
034 *
035 * <p>
036 * The System property {@code file.encoding} is normally set by the JVM in response to the
037 * {@code LANG} or {@code LC_ALL} environment variables. It is used (along with other
038 * platform-dependent variables keyed off those environment variables) to encode JVM
039 * arguments as well as file names and paths. In most cases you can override the file
040 * encoding System property on the command line (with standard JVM features), but also
041 * consider setting the {@code LANG} environment variable to an explicit
042 * character-encoding value (e.g. "en_GB.UTF-8").
043 *
044 * @author Dave Syer
045 * @author Madhura Bhave
046 */
047public class FileEncodingApplicationListener
048                implements ApplicationListener<ApplicationEnvironmentPreparedEvent>, Ordered {
049
050        private static final Log logger = LogFactory
051                        .getLog(FileEncodingApplicationListener.class);
052
053        @Override
054        public int getOrder() {
055                return Ordered.LOWEST_PRECEDENCE;
056        }
057
058        @Override
059        public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
060                ConfigurableEnvironment environment = event.getEnvironment();
061                if (!environment.containsProperty("spring.mandatory-file-encoding")) {
062                        return;
063                }
064                String encoding = System.getProperty("file.encoding");
065                String desired = environment.getProperty("spring.mandatory-file-encoding");
066                if (encoding != null && !desired.equalsIgnoreCase(encoding)) {
067                        logger.error("System property 'file.encoding' is currently '" + encoding
068                                        + "'. It should be '" + desired
069                                        + "' (as defined in 'spring.mandatoryFileEncoding').");
070                        logger.error("Environment variable LANG is '" + System.getenv("LANG")
071                                        + "'. You could use a locale setting that matches encoding='"
072                                        + desired + "'.");
073                        logger.error("Environment variable LC_ALL is '" + System.getenv("LC_ALL")
074                                        + "'. You could use a locale setting that matches encoding='"
075                                        + desired + "'.");
076                        throw new IllegalStateException(
077                                        "The Java Virtual Machine has not been configured to use the "
078                                                        + "desired default character encoding (" + desired + ").");
079                }
080        }
081
082}