[Google Guava] Guava goodness – loading a file from a directory hierarchy
The case:
we want to have an ability to override some static resources in the application
we can have multiple overrides
there is a hierarchy which decides which file is selected if we have multiple overrides
the hierarchy is fixed from the most important to the less important directories
The code:
class HierarchyAwareResourceLoader {
private final List<String> searchPaths;
public HierarchyAwareResourceLoader(List<String> searchPaths){
this.searchPaths = searchPaths;
}
public Optional<File> load(String name){
Optional<File> result = FluentIterable.from(searchPaths).
transform(ConcatPath.with(name)).
transform(File.createFromPath()).
filter(File.ifExists()).
first();
return result;
}
}The other code 😉 :
class ConcatPath implements Function<String,String> {
private final String subPath;
private ConcatPath(String subPath){
this.subPath = subPath;
}
@Override
public String apply(String basePath){
return FilenameUtils.concat(basePath,subPath);
}
public static ConcatPath with(String subPath){
return new ConcatPath(subPath);
}
}
public class FileCreator implements Function<String, File> {
@Override
public File apply(String path){
File result = new File(path);
return result;
}
}
public class FileExistanceChecker implements Predicate<File> {
@Override
public boolean apply(File input){
return input.exists();
}
}
public class File {
public static FileCreator createFromPath(){
return new FileCreator();
}
public static FileExistanceChecker ifExists(){
return new FileExistanceChecker();
}
}
Joy
Tags: fluentIterable , guava , java
This entry was posted
on Monday, March 25th, 2013 at %I:%M %p and is filed under java .
You can follow any responses to this entry through the RSS 2.0 feed.
You can leave a response , or trackback from your own site.
public HierarchyAwareResourceLoader not public HierarchyAware re ResourceLoader
Fixed, thx