Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

https://github.com/drrb/java-rust-example

Embedding Rust in Java
https://github.com/drrb/java-rust-example

Last synced: about 1 month ago
JSON representation

Embedding Rust in Java

Lists

README 

        
# Java/Rust Example



An example project showing how to call into Rust code from Java.



| OSX | Linux | Windows |

| --- | ----- | ------- |

| ![OSX Build Status](https://img.shields.io/badge/build-passing%20on%20my%20laptop-brightgreen.svg) | [![Linux Build Status](https://travis-ci.org/drrb/java-rust-example.svg?branch=master)](https://travis-ci.org/drrb/java-rust-example) | [![Windows Build status](https://ci.appveyor.com/api/projects/status/4yygb3925k7p87de/branch/master?svg=true)](https://ci.appveyor.com/project/drrb/java-rust-example/branch/master) |



## Requirements



- Java 7+

- Rust (tested with 1.0, nightly)



## Contents



So far, the project contains

- Rust code and Java code

- A Java interface to the Rust code, using [JNA](https://github.com/twall/jna)

- A script to build the Rust code into a library and put it on the classpath where JNA can find it

- Examples of passing strings, structs, and callback functions between Java and Rust



## Getting Started



The best place to start looking at the examples is in the test code

([GreetingsTest.java](src/test/java/com/github/drrb/javarust/GreetingsTest.java)).

The test contains lots of executable examples of calling into Rust code from

Java.  From the test, you can navigate to the [Java code](src/main/java/com/github/drrb/javarust/Greetings.java)

and the [Rust code](src/main/rust/com/github/drrb/javarust/lib/greetings.rs). The

implementation is heavily commented to explain it.



So far, it contains examples of the following (click the links to see!):

- *[Arguments](src/test/java/com/github/drrb/javarust/GreetingsTest.java#L45)*: passing simple arguments from Java to Rust ([Java side](src/main/java/com/github/drrb/javarust/Greetings.java#L44) / [Rust side](src/main/rust/com/github/drrb/javarust/lib/greetings.rs#L81))

- *[Return values](src/test/java/com/github/drrb/javarust/GreetingsTest.java#L50)*: returning simple values from Rust to Java ([Java side](src/main/java/com/github/drrb/javarust/Greetings.java#L49) / [Rust side](src/main/rust/com/github/drrb/javarust/lib/greetings.rs#L91))

- *[Struct arguments](src/test/java/com/github/drrb/javarust/GreetingsTest.java#L56)*: passing structs to Rust from Java ([Java side](src/main/java/com/github/drrb/javarust/Greetings.java#L54) / [Rust side](src/main/rust/com/github/drrb/javarust/lib/greetings.rs#L100))

- *[Returning structs (2 examples)](src/test/java/com/github/drrb/javarust/GreetingsTest.java#L65)*: returning structs from Rust by value and by reference ([Java side](src/main/java/com/github/drrb/javarust/Greetings.java#L71) / [Rust side](src/main/rust/com/github/drrb/javarust/lib/greetings.rs#L109))

- *[Callbacks (3 examples)](src/test/java/com/github/drrb/javarust/GreetingsTest.java#L80)*: passing callbacks to Rust that get called from the Rust code ([Java side](src/main/java/com/github/drrb/javarust/Greetings.java#L84) / [Rust side](src/main/rust/com/github/drrb/javarust/lib/greetings.rs#L129))

- *[Freeing memory](src/test/java/com/github/drrb/javarust/GreetingsTest.java#L67)*: freeing memory allocated in Rust ([Java side](src/main/java/com/github/drrb/javarust/Greetings.java#L114) / [Rust side](src/main/rust/com/github/drrb/javarust/lib/greetings.rs#L171))



## Building and Running the Tests



To build the project, and run the tests, use Maven. This will build a jar

containing the Rust code and the Java code. This assumes you have Rust

installed, and on the path.



```

$ mvn package

```



You can then run the jar that is produced to see the integration work.



```

$ java -jar target/greeter.jar John

Hello from Rust, John

```



## Platform Support



This project is tested on OSX, Ubuntu, and Windows. It should also work on any 32 bit or 64 bit Gnu/Linux system.



## Limitations



Some of the examples leak memory. Any memory that is allocated in Rust needs to be freed manually because it's not managed by JNA. Some examples pass objects back into Rust to be dropped for this reason, but we don't clean up everything properly (strings, for example). This is almost certainly not a limitation of Rust, but a limitation of my current understanding of Rust.



## License



Java/Rust Example

Copyright (C) 2015 drrb



This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.



This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.



You should have received a copy of the GNU General Public License

along with this program.  If not, see .