2 unstable releases
0.2.0 | Oct 17, 2022 |
---|---|
0.1.0 | Oct 16, 2022 |
#227 in FFI
12KB
JavaWithRust-Lib
Transfer function calls between Rust and Java in a rust-like (ish) way.
- Github.com : https://github.com/Totobird-Creations/JavaWithRust-Lib
- Crates.io : https://crates.io/crates/javawithrust
- Docs.rs : https://docs.rs/javawithrust
Features
- Call static java functions from rust.
- Call associated rust functions from java.
- Convert java objects to rust structs.
Limitations
- Can not call java methods from rust.
- Can not call rust methods from java.
Setup
Create a dynamic library crate.
# Bash
cargo init . --lib
# Cargo.toml
[dependencies]
javawithrust = "0.1"
serde = {version = "1.0", features = ["derive"]}
[lib]
crate_type = ["cdylib"]
Usage
Get the needed stuff.
// Rust
use javawithrust::prelude::*;
Link a new Java class. This will link JavaObject
(in Rust) and io.example.JavaClassName
(in Java).
// Rust
#[jclass(io.example.JavaClassName)]
pub struct JavaObject;
Link the functions.
// Rust
#[jfuncs]
impl JavaObject {
}
Examples
// Rust
use javawithrust::prelude::*;
#[jclass(io.example.CustomJavaClass)]
pub struct CustomRustStruct;
#[jfuncs]
impl CustomRustStruct {
fn hello() { // Will return `Result<(), String>`
println!("hello");
CustomRustStruct::world()?;
return Ok(());
}
// Will call `io.example.CustomJavaClass.world()`.
fn world();
// Callable from java.
fn sum(a : i32, b : i32) -> i32 { // Will return `Result<i32, String>`
return Ok(a + b);
}
}
// Java
package io.example;
import org.astonbitecode.j4rs.api.Instance;
import org.astonbitecode.j4rs.api.dtos.InvocationArg;
import org.astonbitecode.j4rs.api.java2rust.Java2RustUtils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class ConvHelper {
public static <T> Instance<T> j2rs(T from) {
return Java2RustUtils.createInstance(from);
}
@SuppressWarnings("unchecked")
public static <T> T rs2j(Instance<T> from) {
if (from instanceof InvocationArg) {
InvocationArg from_ia = ((InvocationArg)from);
if (from_ia.isSerialized()) {
ObjectMapper mapper = new ObjectMapper();
try {
return mapper.<T>readValue(from_ia.getJson(), (Class<T>)(Class.forName(from_ia.getClassName())));
} catch (JsonProcessingException | ClassNotFoundException e) {
e.printStackTrace();
System.exit(1);
}
}
}
return Java2RustUtils.getObjectCasted(from);
}
}
// Java
package io.example;
import org.astonbitecode.j4rs.api.Instance;
import org.astonbitecode.j4rs.api.java2rust.Java2RustUtils;
public class CustomJavaClass
{
// Load the dynamic library.
// The library is loaded from the same directory as the jar.
static {
String os=System.getProperty("os.name").toLowerCase();String path=J2RS.class.getProtectionDomain().getCodeSource().getLocation().getPath();path=path.substring(0,path.lastIndexOf("/")).replaceAll("%20"," ")+"/"+
"robot"; // Name of the dynamic library file. `.so` and `.dll` are added automatically.
if (os.contains("linux") || os.contains("unix") || os.contains("android")) {
path += ".so";
} else if (os.contains("win")) {
path += ".dll";
}
else {throw new UnsatisfiedLinkError("Can not load dynamic library in unknown operating system `" + os + "`");}
System.load(path);
}
public static native void hello();
public static void world() {
System.out.println("world!");
}
private static native Instance<Integer> sum(Instance<Integer> i1, Instance<Integer> i2);
public static Integer sumFromRust(Integer a, Integer b) {
// Convert the objects.
return ConvHelper.rs2j(J2RS.sum(
ConvHelper.j2rs(a),
ConvHelper.j2rs(b)
));
}
}
Dependencies
~3–4.5MB
~50K SLoC