feat: add java&rust

__lang/java/java-rust-demo/src/lib.rs

@@ -0,0 +1,7 @@
+use jni::objects::*;
+use jni::JNIEnv;
+
+#[no_mangle]
+pub unsafe extern "C" fn Java_me_hatter_RustJNI_init(_env: JNIEnv, _class: JClass) {
+    println!("rust-java-demo inited");
+}