A simple command line tool to manage Maven dependencies for Java projects that are not using build systems like Maven or Gradle.
It takes inspiration from Node's npm but is more focused on managing dependencies and is not a build tool. Keep using Maven and Gradle for that. This tool is ideal for those who want to compile and run Java code directly without making their lives difficult the moment they want to start using dependencies.
TL;DR
$ jpm install com.github.lalyos:jfiglet:0.0.9
Artifacts new: 1, updated: 0, deleted: 0
$ java -cp deps/* HelloWorld.java
_ _ _ _ __ __ _ _ _
| | | | ___| | | ___ \ \ / /__ _ __| | __| | |
| |_| |/ _ \ | |/ _ \ \ \ /\ / / _ \| '__| |/ _` | |
| _ | __/ | | (_) | \ V V / (_) | | | | (_| |_|
|_| |_|\___|_|_|\___( ) \_/\_/ \___/|_| |_|\__,_(_)Slightly longer explanation:
Imagine you're writing a simple Java console command, and you want to use JFigletFont for some more impactful visuals. You've written the following code:
import com.github.lalyos.jfiglet.FigletFont;
public class HelloWorld {
public static void main(String[] args) throws Exception {
System.out.println(FigletFont.convertOneLine("Hello, World!"));
}
}But now you get to the point that you need to add the JFigletFont library to your project. You could start
using Maven or Gradle, but that seems overkill for such a simple project. Instead, you can use jpm.
First you can search for the library if you can't remember the exact name and version:
$ jpm search jfiglet
com.github.dtmo.jfiglet:jfiglet:1.0.1
com.github.lalyos:jfiglet:0.0.9So let's install the second library from that list:
$ jpm install com.github.lalyos:jfiglet:0.0.9
Artifacts new: 1, updated: 0, deleted: 0Let's see what that did:
$ tree
.
├── app.yml
├── deps
│ └── jfiglet-0.0.9.jar -> /home/user/.m2/repository/com/github/lalyos/jfiglet/0.0.9/jfiglet-0.0.9.jar
└── HelloWorld.javaAs you can see jpm has created a deps directory and copied the JFigletFont library there
(although in fact it didn't actually copy the library itself, but instead it created a symbolic link to save space).
We can now simply run the program like this (using Java 11 or newer):
$ java -cp "deps/*" HelloWorld.java
_ _ _ _ __ __ _ _ _
| | | | ___| | | ___ \ \ / /__ _ __| | __| | |
| |_| |/ _ \ | |/ _ \ \ \ /\ / / _ \| '__| |/ _` | |
| _ | __/ | | (_) | \ V V / (_) | | | | (_| |_|
|_| |_|\___|_|_|\___( ) \_/\_/ \___/|_| |_|\__,_(_)But if we look again at the above output of tree, we also see an app.yml file.
This file is used by jpm to keep track of the dependencies of your project. If you want to share your project
with someone else, you can simply share the app.yml file along with the code, and they can run jpm install
to get the required dependencies to run the code.
NB: We could have used jpm copy instead of jpm install to copy the dependencies but that would not have created
the app.yml file.
The app.yml file doesn't just track dependencies - it can also define custom actions that can be executed with the jpm do command or through convenient alias commands.
Actions are defined in the actions section of your app.yml file:
dependencies:
com.github.lalyos:jfiglet:0.0.9
actions:
build: "javac -cp {{deps}} *.java"
run: "java -cp {{deps}} HelloWorld"
test: "java -cp {{deps}} TestRunner"
clean: "rm -f *.class"You can execute actions using the jpm do command:
$ jpm do build
$ jpm do run
$ jpm do --list # Lists all available actionsOr use the convenient alias commands:
$ jpm build # Executes the 'build' action
$ jpm run # Executes the 'run' action
$ jpm test # Executes the 'test' action
$ jpm clean # Executes the 'clean' actionAlias commands can accept additional arguments that will be passed through to the underlying action:
$ jpm run --verbose debug # Passes '--verbose debug' to the run actionActions support several variable substitution features for cross-platform compatibility:
{{deps}}- Replaced with the full classpath of all dependencies{/}- Replaced with the file separator (\on Windows,/on Linux/Mac){:}- Replaced with the path separator (;on Windows,:on Linux/Mac){~}- Replaced with the user's home directory (The actual path on Windows,~on Linux/Mac){./path/to/file}- Converts relative paths to platform-specific format{./libs:./ext:~/usrlibs}- Converts entire class paths to platform-specific format{;}- For use with multi-command actions (&on Windows,;on Linux/Mac). Really not that useful, you can use&&instead which works on all platforms
Example with cross-platform compatibility:
actions:
build: "javac -cp {{deps}} -d {./target/classes} src{/}*.java"
run: "java -cp {{deps}}{:}{./target/classes} Main"
test: "java -cp {{deps}}{:}{./target/classes} org.junit.runner.JUnitCore TestSuite"NB: The {{deps}} variable substitution is only performed when needed - if your action doesn't contain {{deps}}, jpm won't resolve the classpath, making execution faster for simple actions that don't require dependencies.
NB2: These actions are just a very simple convenience feature. For a much more full-featured cross-platform action runner I recommend taking a look at:
- Just - Just a command runner
For now the simplest way to install jpm is to use JBang:
jbang app install jpm@codejiveBut you can also simply download and unzip the release package and run the bin/jpm script.
See:
$ jpm --help
Usage: jpm [-hV] [COMMAND]
Simple command line tool for managing Maven artifacts
-h, --help Show this help message and exit.
-V, --version Print version information and exit.
Commands:
copy, c Resolves one or more artifacts and copies them and all their
dependencies to a target directory. By default jpm will try to
create symbolic links to conserve space.
Example:
jpm copy org.apache.httpcomponents:httpclient:4.5.14
search, s Without arguments this command will start an interactive search
asking the user to provide details of the artifact to look for
and the actions to take. When provided with an argument this
command finds and returns the names of those artifacts that
match the given (partial) name.
Example:
jpm search httpclient
install, i This adds the given artifacts to the list of dependencies
available in the app.yml file. It then behaves just like 'copy
--sync' and copies all artifacts in that list and all their
dependencies to the target directory while at the same time
removing any artifacts that are no longer needed (ie the ones
that are not mentioned in the app.yml file). If no artifacts
are passed the app.yml file will be left untouched and only the
existing dependencies in the file will be copied.
Example:
jpm install org.apache.httpcomponents:httpclient:4.5.14
path, p Resolves one or more artifacts and prints the full classpath to
standard output. If no artifacts are passed the classpath for
the dependencies defined in the app.yml file will be printed
instead.
Example:
jpm path org.apache.httpcomponents:httpclient:4.5.14
do Executes an action command defined in the app.yml file. Actions
can use variable substitution for classpath.
Example:
jpm do build
jpm do test
clean Executes the 'clean' action as defined in the app.yml file.
build Executes the 'build' action as defined in the app.yml file.
run Executes the 'run' action as defined in the app.yml file.
test Executes the 'test' action as defined in the app.yml file.To build the project simply run:
./mvnw spotless:apply clean install