File _expression_ Language
Available as of Camel 1.5
The File _expression_ Language is an extension to the Simple language, adding file related capabilities. These capabilities is related to common use cases working with file path and names. The goal is to allow _expression_ to be used with the File and FTP components for setting dynamic file patterns for both consumer and producer.
Syntax
This language is an extension to the Simple language so the Simple syntax applies also. So the table below only lists the additional.
As opposed to Simple language File Language also supports Constant expressions so you can enter a fixed filename.
All the file tokens uses the same _expression_ name as the method on the java.io.File object, for instance file:absolute![]()
refers to the java.io.File.getAbsolute() method. Notice that not all expressions is supported by the current Exchange. For instance the FTP component only supports a few of the options, where as the File component support all of them.
| _expression_ |
Type |
File Consumer |
File Producer |
FTP Consumer |
FTP Producer |
Description |
file:name![]() |
String |
yes |
no |
yes |
no |
refers to the file name |
file:name.ext![]() |
String |
yes |
no |
yes |
no |
Camel 2.0: refers to the file extension only |
file:name.noext![]() |
String |
yes |
no |
yes |
no |
refers to the file name with no extension |
file:parent![]() |
String |
yes |
no |
yes |
no |
refers to the file parent |
file:path![]() |
String |
yes |
no |
yes |
no |
refers to the file path |
file:absolute![]() |
Boolean |
yes |
no |
no |
no |
Camel 2.0: refers to whether the file is regarded as absolute or relative |
file:absolute.path![]() |
String |
yes |
no |
no |
no |
refers to the absolute file path |
file:canonical.path![]() |
String |
yes |
no |
no |
no |
refers to the canonical path |
file:length![]() |
Long |
yes |
no |
yes |
no |
refers to the file length returned as a Long type |
file:modified![]() |
Date |
yes |
no |
yes |
no |
Camel 2.0: refers to the file last modified returned as a Date type |
| date:command:pattern |
String |
yes |
yes |
yes |
yes |
for date formatting using the java.text.SimepleDataFormat patterns. Is an extension to the Simple language. Additional command is: file (consumers only) for the last modified timestamp of the file. Notice: all the commands from the Simple language can also be used. |
File token example
We have a java.io.File handle for the file hello.txt in the following directory: D:\project\camel\camel-core\target\filelanguage. The file tokens will return as:
Samples
You can enter a fixed Constant _expression_ such as myfile.txt:
_expression_="myfile.txt"
Lets assume we use the file consumer to read files and want to move the read files to backup folder with the current date as a sub folder. This can be archived using an _expression_ like:
_expression_="backup/${date:now:yyyyMMdd}/${file:name.noext}.bak"
relative folder names is also supported so suppose the backup folder should be a sibling folder then you can append .. as:
_expression_="../backup/${date:now:yyyyMMdd}/${file:name.noext}.bak"
As this is an extension to the Simple language we have access to all the goodies from this language also, so in this use case we want to use the in.header.type as a parameter in the dynamic _expression_:
_expression_="../backup/${date:now:yyyyMMdd}/type-${in.header.type}/backup-of-${file:name.noext}.bak"
If you have a custom Date you want to use in the _expression_ then Camel supports retrieving dates from the message header.
_expression_="orders/order-${in.header.customerId}-${date:in.header.orderDate:yyyyMMdd}.xml"
And finally we can also use a bean _expression_ to invoke a POJO class that generates some String output (or convertible to String) to be used:
_expression_="uniquefile-${bean:myguidgenerator.generateid}.txt"
And of course all this can be combined in one _expression_ where you can use the File Language, Simple and the Bean language in one combined _expression_. This is pretty powerful for those common file path patterns.
Dependencies
The File language is part of camel-core.
