src/main/java/de/todesbaum/jsite/main/JarFileLocator.java

   1 package de.todesbaum.jsite.main;
   2
   3 import static java.util.Optional.empty;
   4
   5 import java.io.File;
   6 import java.io.UnsupportedEncodingException;
   7 import java.net.URL;
   8 import java.net.URLDecoder;
   9 import java.util.Optional;
  10
  11 /**
  12  * Locates the JAR file used to load jSite in the filesystem.
  13  */
  14 public interface JarFileLocator {
  15
  16         Optional<File> locateJarFile();
  17
  18         class DefaultJarFileLocator implements JarFileLocator {
  19
  20                 private final ClassLoader classLoader;
  21
  22                 public DefaultJarFileLocator(ClassLoader classLoader) {
  23                         this.classLoader = classLoader;
  24                 }
  25
  26                 @Override
  27                 public Optional<File> locateJarFile() {
  28                         URL resourceUrl = classLoader.getResource(Main.class.getName().replace(".", "/") + ".class");
  29                         if (resourceUrl == null) {
  30                                 return empty();
  31                         }
  32                         String resource = resourceUrl.toString();
  33                         if (resource.startsWith("jar:")) {
  34                                 try {
  35                                         String jarFileLocation = URLDecoder.decode(resource.substring(9, resource.indexOf(".jar!") + 4), "UTF-8");
  36                                         return Optional.of(new File(jarFileLocation));
  37                                 } catch (UnsupportedEncodingException e) {
  38                                         /* location is not available, ignore. */
  39                                 }
  40                         }
  41                         return empty();
  42                 }
  43         }
  44
  45 }