runtime/org.argeo.slc.osgiboot/src/main/java/org/argeo/slc/osgiboot/internal/springutil/SystemPropertyUtils.java

   1 /*
   2  * Copyright 2002-2008 the original author or authors.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 package org.argeo.slc.osgiboot.internal.springutil;
  18
  19 /**
  20  * Helper class for resolving placeholders in texts. Usually applied to file paths.
  21  *
  22  * <p>A text may contain <code>${...}</code> placeholders, to be resolved as
  23  * system properties: e.g. <code>${user.dir}</code>.
  24  *
  25  * @author Juergen Hoeller
  26  * @since 1.2.5
  27  * @see #PLACEHOLDER_PREFIX
  28  * @see #PLACEHOLDER_SUFFIX
  29  * @see System#getProperty(String)
  30  */
  31 public abstract class SystemPropertyUtils {
  32
  33         /** Prefix for system property placeholders: "${" */
  34         public static final String PLACEHOLDER_PREFIX = "${";
  35
  36         /** Suffix for system property placeholders: "}" */
  37         public static final String PLACEHOLDER_SUFFIX = "}";
  38
  39
  40         /**
  41          * Resolve ${...} placeholders in the given text,
  42          * replacing them with corresponding system property values.
  43          * @param text the String to resolve
  44          * @return the resolved String
  45          * @see #PLACEHOLDER_PREFIX
  46          * @see #PLACEHOLDER_SUFFIX
  47          */
  48         public static String resolvePlaceholders(String text) {
  49                 StringBuffer buf = new StringBuffer(text);
  50
  51                 int startIndex = buf.indexOf(PLACEHOLDER_PREFIX);
  52                 while (startIndex != -1) {
  53                         int endIndex = buf.indexOf(PLACEHOLDER_SUFFIX, startIndex + PLACEHOLDER_PREFIX.length());
  54                         if (endIndex != -1) {
  55                                 String placeholder = buf.substring(startIndex + PLACEHOLDER_PREFIX.length(), endIndex);
  56                                 int nextIndex = endIndex + PLACEHOLDER_SUFFIX.length();
  57                                 try {
  58                                         String propVal = System.getProperty(placeholder);
  59                                         if (propVal == null) {
  60                                                 // Fall back to searching the system environment.
  61                                                 propVal = System.getenv(placeholder);
  62                                         }
  63                                         if (propVal != null) {
  64                                                 buf.replace(startIndex, endIndex + PLACEHOLDER_SUFFIX.length(), propVal);
  65                                                 nextIndex = startIndex + propVal.length();
  66                                         }
  67                                         else {
  68                                                 System.err.println("Could not resolve placeholder '" + placeholder + "' in [" + text +
  69                                                                 "] as system property: neither system property nor environment variable found");
  70                                         }
  71                                 }
  72                                 catch (Throwable ex) {
  73                                         System.err.println("Could not resolve placeholder '" + placeholder + "' in [" + text +
  74                                                         "] as system property: " + ex);
  75                                 }
  76                                 startIndex = buf.indexOf(PLACEHOLDER_PREFIX, nextIndex);
  77                         }
  78                         else {
  79                                 startIndex = -1;
  80                         }
  81                 }
  82
  83                 return buf.toString();
  84         }
  85
  86 }