Practical Work 1 - IoProcessing CLI

This is a CLI that allows you to apply some operations on text and binary files.

Dependencies

commons-codec

To simplify the processing of encoding files as base64, we are using the commons-codec utility library from Apache which provides a simple API to encode and decode data in various formats.

Build the JAR

To build the JAR, run the following command from the root of the repository:

./mvnw clean package

Running

To run the JAR, run the following command from the root of the repository:

java -jar target/pw-cli-ioprocessing-1.0.0-SNAPSHOT.jar <command>

Usage

The CLI methods are documented in the form of usage messages, given using the --help flag.

java -jar target/pw-cli-ioprocessing-1.0.0-SNAPSHOT.jar --help

Commands

The CLI supports the following commands:

• copy: Copies a binary file to another.
• lowercase: Transforms a text file, making it all lowercase.
• uppercase: Transforms a text file, making it all uppercase.
• base64: Encodes and decodes any file to and from the base64 format.
• sha3: Computes the SHA3 hash of a file and prints it in the output file.

Testing

For testing, a couple of files are given in src/test/resources/test-files.

For example, the copy operation can be done that way (from the current directory):

java -jar target/pw-cli-ioprocessing-1.0.0-SNAPSHOT.jar copy \
    -i src/test/resources/test-files/utf8.txt \
    -o target/copy.txt

Which outputs the following:

❯ java -jar target/pw-cli-ioprocessing-1.0.0-SNAPSHOT.jar copy -i src/test/resources/test-files/uppercase-long.txt -o target/copy.txt
17:11:22.553 [main] INFO ch.lutonite.heig.dai.pw01.command.CopyCommand -- Starting operation on file src/test/resources/test-files/utf8.txt to target/copy.txt
17:11:22.578 [main] INFO ch.lutonite.heig.dai.pw01.command.CopyCommand -- Operation completed in 23 ms

And, as expected, the contents of target/copy.txt are identical to src/test/resources/test-files/uppercase-long.txt.

Encoding

For text operations (lowercase and uppercase, for example), two more arguments are available (but optional).

• --input-encoding allows to define the input encoding
• --output-encoding allows to define the output encoding

Warning If there is a mismatch between the actual file encoding and the given input/output encoding, the CLI will return an error message. This CLI does not handle conversion between character sets, unless they are strictly compatible (e.g US-ASCII is a subset of UTF-8).