Add support Java bindings

This add support for Java bindings in the bindings/java directory.

bindings/java/rs_src/lib.rs

@@ -0,0 +1,66 @@
+mod connection;
+mod cursor;
+mod errors;
+mod macros;
+mod utils;
+
+use crate::connection::Connection;
+use crate::errors::ErrorCode;
+use jni::errors::JniError;
+use jni::objects::{JClass, JString};
+use jni::sys::jlong;
+use jni::JNIEnv;
+use std::sync::{Arc, Mutex};
+
+/// Establishes a connection to the database specified by the given path.
+///
+/// This function is called from the Java side to create a connection to the database.
+/// It returns a pointer to the `Connection` object, which can be used in subsequent
+/// native function calls.
+///
+/// # Arguments
+///
+/// * `env` - The JNI environment pointer.
+/// * `_class` - The Java class calling this function.
+/// * `path` - A `JString` representing the path to the database file.
+///
+/// # Returns
+///
+/// A `jlong` representing the pointer to the newly created `Connection` object,
+/// or [ErrorCode::CONNECTION_FAILURE] if the connection could not be established.
+#[no_mangle]
+pub extern "system" fn Java_org_github_tursodatabase_limbo_Limbo_connect<'local>(
+    mut env: JNIEnv<'local>,
+    _class: JClass<'local>,
+    path: JString<'local>,
+) -> jlong {
+    connect_internal(&mut env, path).unwrap_or_else(|_| ErrorCode::CONNECTION_FAILURE as jlong)
+}
+
+#[allow(improper_ctypes_definitions, clippy::arc_with_non_send_sync)] // TODO: remove
+fn connect_internal<'local>(
+    env: &mut JNIEnv<'local>,
+    path: JString<'local>,
+) -> Result<jlong, JniError> {
+    let io = Arc::new(limbo_core::PlatformIO::new().map_err(|e| {
+        println!("IO initialization failed: {:?}", e);
+        JniError::Unknown
+    })?);
+
+    let path: String = env
+        .get_string(&path)
+        .expect("Failed to convert JString to Rust String")
+        .into();
+    let db = limbo_core::Database::open_file(io.clone(), &path).map_err(|e| {
+        println!("Failed to open database: {:?}", e);
+        JniError::Unknown
+    })?;
+
+    let conn = db.connect().clone();
+    let connection = Connection {
+        conn: Arc::new(Mutex::new(conn)),
+        io,
+    };
+
+    Ok(Box::into_raw(Box::new(connection)) as jlong)
+}