Let the butler take care of it while you attend to more pressing matters
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Butler IO

Some of those IO tasks can simply be the height of tedium. Why not ask the butler to take care of it? He's rather clever don't you know, he even understands a thing or two about that apache VFS.

Butler will fetch

  • byte []
  • String
  • String in utf8
  • InputStream
  • File


  • VFS locations - allows loading from any of; local files, http, https, ftp, sftp, temporary files, zip, jar, tar, gzip, bzip2, res, ram, mime. Take a look at some examples.
  • InputStreams
  • Files
  • File in same package as a Class


Just add the butler-io dependency to your maven settings with



First let's call for the butler:

import static uk.co.opsb.butler.ButlerIO.*;

Now let's put him to task

Fetching text

String fromClasspath          = textFrom( "res:articles/steve_jobs.txt" );
String fromUtf8File           = utf8From( "file:///path/to/steve_jobs.txt" );
String fromUtf8FileOnWindows  = utf8From( "file:///c:/path/to/steve_jobs.txt" );
String fromInputStream        = textFrom( inputStream );
String overHttpsUsingVfs      = textFrom( "https://username:password@domain_name.com/article.txt" );
String fromFtpZipUsingVfs     = textFrom( "zip:ftp://username:password@domain_name.com/file.txt.zip" );
String fromFileNextToClass    = textFrom( "name_of_file_in_same_package_as", YourClass.class );

Writing text

write( "some text", "tmp://text_file.txt" );
writeUtf8( "some text", "tmp://utf8_text_file.txt" );

Fetching bytes

byte [] fromClasspath          = bytesFrom( "res:articles/steve_jobs.txt" );
byte [] fromUtf8File           = bytesFrom( "file:///path/to/steve_jobs.txt" );
byte [] fromUtf8FileOnWindows  = bytesFrom( "file:///c:/path/to/steve_jobs.txt" );
byte [] fromInputStream        = bytesFrom( inputStream );
byte [] overHttpUsingVfs       = bytesFrom( "https://domain_name.com/article.txt" );
byte [] fromSftpGzipUsingVfs   = bytesFrom( "gz:sftp://username:password@domain_name.com/file.txt.gz" );   
byte [] fromFileNextToClass    = bytesFrom( "name_of_file_in_same_package_as", YourClass.class );     

Writing bytes

write( image.getBytes(), "tmp://image.jpg" );

Fetching properties

Properties fromClasspath          = propertiesFrom( "res:articles/steve_jobs.txt" );
Properties fromUtf8File           = propertiesFrom( "file:///path/to/steve_jobs.txt" );
Properties fromUtf8FileOnWindows  = propertiesFrom( "file:///c:/path/to/steve_jobs.txt" );
Properties fromInputStream        = propertiesFrom( inputStream );
Properties overHttpsUsingVfs      = propertiesFrom( "https://username:password@domain_name.com/article.txt" );
Properties fromJarUsingVfs        = propertiesFrom( "jar://username:password@domain_name.com/outer.jar!inner/file.txt" );   
Properties fromFileNextToClass    = propertiesFrom( "name_of_file_in_same_package_as", YourClass.class );    

Opening an InputStream

InputStream fromClasspath          = inputStreamFrom( "res:articles/steve_jobs.txt" );
InputStream fromUtf8File           = inputStreamFrom( "file:///path/to/steve_jobs.txt" );
InputStream fromUtf8FileOnWindows  = inputStreamFrom( "file:///c:/path/to/steve_jobs.txt" );
InputStream overHttpsUsingVfs      = inputStreamFrom( "https://username:password@domain_name.com/article.txt" );
InputStream fromFtpZipUsingVfs     = inputStreamFrom( "zip:ftp://username:password@domain_name.com/file.txt.zip" );   
InputStream fromFileNextToClass    = inputStreamFrom( "name_of_file_in_same_package_as", YourClass.class );    

Getting a reference to a File

File fromClasspath          = fileFrom( "res:path/to/file" );
File fromFileNextToClass    = fileFrom( "file_name", YourClass.class );


I often need to fetch articles and reports from the same places. I don't know about you but I rather like my butler to show a little initiative.

#Inside a file at {classpath}/butler_aliases.properties
articles\:=res://path/to/articles    # remember to escape any colons you use before the equals

Now when I ask for articles and reports he'll know just what to do

String article = textFrom( "articles:steve_jobs.txt" ); // => res:path/to/articles/steve_jobs.txt
String report  = textFrom( "reports:q4_figures.txt" ); // => res:path/to/reports/q4_figures.txt

Marvellous. He can do better than that though, how about we use a convention


String article = textFrom( "articles:steve_jobs.txt" ); // => res:uk/co/opsb/articles/steve_jobs.txt
String report  = textFrom( "reports:q4_figures.txt" ); // => res:uk/co/opsb/reports/q4_figures.txt

What a clever chap. He's used the regex to capture articles/reports and then String.format to merge them in.