Merge pull request #41 from EliseChouleur/jbyte-type

Add capability to call java byte array

README.md

@@ -122,6 +122,7 @@ You can make a Rust native method raise a Java exception simply by returning a `
 | i16                                                                                | short                             |
 | String                                                                             | String                            |
 | Vec\<T\>†                                                                          | ArrayList\<T\>                    |
+| Box<[u8]>                                                                          | byte[]                            |
 | [jni::JObject<'env>](https://docs.rs/jni/0.17.0/jni/objects/struct.JObject.html) ‡ | *(any Java object as input type)* |
 | [jni::jobject](https://docs.rs/jni/0.17.0/jni/sys/type.jobject.html)               | *(any Java object as output)*     |
 

src/convert/safe.rs

@@ -18,7 +18,7 @@
 
 use jni::errors::{Error, Result};
 use jni::objects::{JList, JObject, JString, JValue};
-use jni::sys::{jboolean, jbooleanArray, jchar, jobject};
+use jni::sys::{jboolean, jbooleanArray, jbyteArray, jchar, jobject};
 use jni::JNIEnv;
 
 use crate::convert::unchecked::{FromJavaValue, IntoJavaValue};
@@ -247,6 +247,28 @@ where
     }
 }
 
+impl Signature for Box<[u8]> {
+    const SIG_TYPE: &'static str = "[B";
+}
+
+impl<'env> TryIntoJavaValue<'env> for Box<[u8]> {
+    type Target = jbyteArray;
+
+    fn try_into(self, env: &JNIEnv<'env>) -> Result<Self::Target> {
+        env.byte_array_from_slice(self.as_ref())
+    }
+}
+
+impl<'env: 'borrow, 'borrow> TryFromJavaValue<'env, 'borrow> for Box<[u8]> {
+    type Source = jbyteArray;
+
+    fn try_from(s: Self::Source, env: &'borrow JNIEnv<'env>) -> Result<Box<[u8]>> {
+        let buf = env.convert_byte_array(s)?;
+        let boxed_slice = buf.into_boxed_slice();
+        Ok(boxed_slice)
+    }
+}
+
 /// When returning a [`jni::errors::Result`], if the returned variant is `Ok(v)` then the value `v` is returned as usual.
 ///
 /// If the returned value is `Err`, the Java exception specified in the `#[call_type(safe)]` attribute is thrown

tests/driver/native/src/lib.rs

@@ -91,6 +91,10 @@ pub mod jni {
             v
         }
 
+        pub extern "jni" fn getByteArray(self, v: Box<[u8]>) -> Box<[u8]> {
+            v
+        }
+
         pub extern "jni" fn intToString(self, v: i32) -> String {
             format!("{}", v)
         }
@@ -131,6 +135,10 @@ pub mod jni {
             format!("{:?}", v)
         }
 
+        pub extern "jni" fn byteArrayToString(self, v: Box<[u8]>) -> String {
+            format!("{:?}", v)
+        }
+
         pub extern "java" fn getPassword(
             &self,
             env: &JNIEnv,

tests/driver/src/main/java/User.java

@@ -33,6 +33,8 @@ public class User {
 
     public native List<String> getStringArray(List<String> x);
 
+    public native byte[] getByteArray(byte[] x);
+
     public native String intToString(int x);
 
     public native String boolToString(boolean x);
@@ -53,6 +55,8 @@ public class User {
 
     public native String stringArrayToString(List<String> x);
 
+    public native String byteArrayToString(byte[] x);
+
     private native static void initNative();
 
     public native static String userCountStatus();

tests/driver/src/test/java/UserTest.java

@@ -5,6 +5,7 @@
 import java.util.function.Function;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 
 public class UserTest {
     private User u;
@@ -135,6 +136,12 @@ public void stringArrayTest() {
         assertValueRoundTrip(u::getStringArray, u::stringArrayToString, List.of("a", "b", "c"), "[\"a\", \"b\", \"c\"]");
     }
 
+    @Test
+    public void byteArrayTest() {
+        assertArrayValueRoundTrip(u::getByteArray, u::byteArrayToString, new byte[0], "[]");
+        assertArrayValueRoundTrip(u::getByteArray, u::byteArrayToString, new byte[] {1, 2, 3}, "[1, 2, 3]");
+    }
+
     @Test
     public void staticMethod() {
         assertEquals(String.valueOf(User.getTotalUsersCount()), User.userCountStatus());
@@ -144,4 +151,9 @@ private <T> void assertValueRoundTrip(Function<T, T> func, Function<T, String> t
         assertEquals(value, func.apply(value));
         assertEquals(text, toString.apply(value));
     }
+
+    private <T> void assertArrayValueRoundTrip(Function<byte[], byte[]> func, Function<byte[], String> toString, byte[] value, String text) {
+        assertArrayEquals(value, func.apply(value));
+        assertEquals(text, toString.apply(value));
+    }
 }