fix: blob usage after resultset move

src/jni/duckdb_java.cpp

@@ -994,15 +994,20 @@ jobject ProcessVector(JNIEnv *env, Connection *conn_ref, Vector &vec, idx_t row_
 		break;
 	}
 	case LogicalTypeId::BLOB:
-		varlen_data = env->NewObjectArray(row_count, J_ByteBuffer, nullptr);
+		varlen_data = env->NewObjectArray(row_count, J_ByteArray, nullptr);
 
 		for (idx_t row_idx = 0; row_idx < row_count; row_idx++) {
 			if (FlatVector::IsNull(vec, row_idx)) {
 				continue;
 			}
 			auto &d_str = ((string_t *)FlatVector::GetData(vec))[row_idx];
-			auto j_obj = env->NewDirectByteBuffer((void *)d_str.GetData(), d_str.GetSize());
-			env->SetObjectArrayElement(varlen_data, row_idx, j_obj);
+
+			auto j_arr = env->NewByteArray(d_str.GetSize());
+			auto j_arr_el = env->GetByteArrayElements(j_arr, nullptr);
+			memcpy((void *)j_arr_el, (void *)d_str.GetData(), d_str.GetSize());
+			env->ReleaseByteArrayElements(j_arr, j_arr_el, 0);
+
+			env->SetObjectArrayElement(varlen_data, row_idx, j_arr);
 		}
 		break;
 	case LogicalTypeId::UUID:

src/main/java/org/duckdb/DuckDBVector.java

@@ -278,7 +278,7 @@ Blob getBlob(int idx) throws SQLException {
             return null;
         }
         if (isType(DuckDBColumnType.BLOB)) {
-            return new DuckDBResultSet.DuckDBBlobResult((ByteBuffer) varlen_data[idx]);
+            return new DuckDBResultSet.DuckDBBlobResult(ByteBuffer.wrap((byte[]) varlen_data[idx]));
         }
 
         throw new SQLFeatureNotSupportedException("getBlob");
@@ -290,11 +290,7 @@ byte[] getBytes(int idx) throws SQLException {
         }
 
         if (isType(DuckDBColumnType.BLOB)) {
-            ByteBuffer bb = (ByteBuffer) varlen_data[idx];
-            bb.position(0);
-            byte[] bytes = new byte[bb.remaining()];
-            bb.get(bytes);
-            return bytes;
+            return (byte[]) varlen_data[idx];
         }
 
         throw new SQLFeatureNotSupportedException("getBytes");

src/test/java/org/duckdb/TestDuckDBJDBC.java

@@ -4604,6 +4604,20 @@ public static void test_metadata_get_index_info() throws Exception {
         }
     }
 
+    public static void test_blob_after_rs_next() throws Exception {
+        try (Connection conn = DriverManager.getConnection(JDBC_URL)) {
+            try (Statement stmt = conn.createStatement()) {
+                try (ResultSet rs = stmt.executeQuery("SELECT 'AAAA'::BLOB;")) {
+                    Blob blob = null;
+                    while (rs.next()) {
+                        blob = rs.getBlob(1);
+                    }
+                    assertEquals(blob_to_string(blob), "AAAA");
+                }
+            }
+        }
+    }
+
     public static void main(String[] args) throws Exception {
         System.exit(runTests(args, TestDuckDBJDBC.class, TestExtensionTypes.class));
     }