001/*
002 * Copyright 2012-2018 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.system;
018
019import java.io.File;
020import java.security.MessageDigest;
021
022import org.springframework.util.Assert;
023import org.springframework.util.StringUtils;
024
025/**
026 * Provides access to an application specific temporary directory. Generally speaking
027 * different Spring Boot applications will get different locations, however, simply
028 * restarting an application will give the same location.
029 *
030 * @author Phillip Webb
031 * @since 2.0.0
032 */
033public class ApplicationTemp {
034
035        private static final char[] HEX_CHARS = "0123456789ABCDEF".toCharArray();
036
037        private final Class<?> sourceClass;
038
039        private volatile File dir;
040
041        /**
042         * Create a new {@link ApplicationTemp} instance.
043         */
044        public ApplicationTemp() {
045                this(null);
046        }
047
048        /**
049         * Create a new {@link ApplicationTemp} instance for the specified source class.
050         * @param sourceClass the source class or {@code null}
051         */
052        public ApplicationTemp(Class<?> sourceClass) {
053                this.sourceClass = sourceClass;
054        }
055
056        @Override
057        public String toString() {
058                return getDir().getAbsolutePath();
059        }
060
061        /**
062         * Return a sub-directory of the application temp.
063         * @param subDir the sub-directory name
064         * @return a sub-directory
065         */
066        public File getDir(String subDir) {
067                File dir = new File(getDir(), subDir);
068                dir.mkdirs();
069                return dir;
070        }
071
072        /**
073         * Return the directory to be used for application specific temp files.
074         * @return the application temp directory
075         */
076        public File getDir() {
077                if (this.dir == null) {
078                        synchronized (this) {
079                                byte[] hash = generateHash(this.sourceClass);
080                                this.dir = new File(getTempDirectory(), toHexString(hash));
081                                this.dir.mkdirs();
082                                Assert.state(this.dir.exists(),
083                                                () -> "Unable to create temp directory " + this.dir);
084                        }
085                }
086                return this.dir;
087        }
088
089        private File getTempDirectory() {
090                String property = System.getProperty("java.io.tmpdir");
091                Assert.state(StringUtils.hasLength(property), "No 'java.io.tmpdir' property set");
092                File file = new File(property);
093                Assert.state(file.exists(), () -> "Temp directory " + file + " does not exist");
094                Assert.state(file.isDirectory(),
095                                () -> "Temp location " + file + " is not a directory");
096                return file;
097        }
098
099        private byte[] generateHash(Class<?> sourceClass) {
100                ApplicationHome home = new ApplicationHome(sourceClass);
101                MessageDigest digest;
102                try {
103                        digest = MessageDigest.getInstance("SHA-1");
104                        update(digest, home.getSource());
105                        update(digest, home.getDir());
106                        update(digest, System.getProperty("user.dir"));
107                        update(digest, System.getProperty("java.home"));
108                        update(digest, System.getProperty("java.class.path"));
109                        update(digest, System.getProperty("sun.java.command"));
110                        update(digest, System.getProperty("sun.boot.class.path"));
111                        return digest.digest();
112                }
113                catch (Exception ex) {
114                        throw new IllegalStateException(ex);
115                }
116        }
117
118        private void update(MessageDigest digest, Object source) {
119                if (source != null) {
120                        digest.update(getUpdateSourceBytes(source));
121                }
122        }
123
124        private byte[] getUpdateSourceBytes(Object source) {
125                if (source instanceof File) {
126                        return getUpdateSourceBytes(((File) source).getAbsolutePath());
127                }
128                return source.toString().getBytes();
129        }
130
131        private String toHexString(byte[] bytes) {
132                char[] hex = new char[bytes.length * 2];
133                for (int i = 0; i < bytes.length; i++) {
134                        int b = bytes[i] & 0xFF;
135                        hex[i * 2] = HEX_CHARS[b >>> 4];
136                        hex[i * 2 + 1] = HEX_CHARS[b & 0x0F];
137                }
138                return new String(hex);
139        }
140
141}