From 08c8520b39083ec6354dc5df2f18c1f4c3588053 Mon Sep 17 00:00:00 2001
From: Patrick Strawderman <patrick@kilink.net>
Date: Wed, 4 Mar 2026 20:04:30 +0000
Subject: [PATCH] 8378698: Optimize Base64.Encoder#encodeToString

Reviewed-by: liach, rriggs
---
 .../share/classes/java/util/Base64.java       |  6 +-
 .../bench/java/util/Base64EncodeToString.java | 55 +++++++++++++++++++
 2 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100644 test/micro/org/openjdk/bench/java/util/Base64EncodeToString.java

diff --git a/src/java.base/share/classes/java/util/Base64.java b/src/java.base/share/classes/java/util/Base64.java
index ed1a4a8d638..fd714050149 100644
--- a/src/java.base/share/classes/java/util/Base64.java
+++ b/src/java.base/share/classes/java/util/Base64.java
@@ -32,6 +32,8 @@ import java.io.OutputStream;
 import java.nio.ByteBuffer;
 
 import sun.nio.cs.ISO_8859_1;
+import jdk.internal.access.JavaLangAccess;
+import jdk.internal.access.SharedSecrets;
 import jdk.internal.util.Preconditions;
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 
@@ -201,6 +203,7 @@ public final class Base64 {
      * @since   1.8
      */
     public static class Encoder {
+        private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
 
         private final byte[] newline;
         private final int linemax;
@@ -344,10 +347,9 @@ public final class Base64 {
          *          the byte array to encode
          * @return  A String containing the resulting Base64 encoded characters
          */
-        @SuppressWarnings("deprecation")
         public String encodeToString(byte[] src) {
             byte[] encoded = encode(src);
-            return new String(encoded, 0, 0, encoded.length);
+            return JLA.uncheckedNewStringWithLatin1Bytes(encoded);
         }
 
         /**
diff --git a/test/micro/org/openjdk/bench/java/util/Base64EncodeToString.java b/test/micro/org/openjdk/bench/java/util/Base64EncodeToString.java
new file mode 100644
index 00000000000..5b259230341
--- /dev/null
+++ b/test/micro/org/openjdk/bench/java/util/Base64EncodeToString.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.micro.bench.java.util;
+
+import org.openjdk.jmh.annotations.*;
+
+import java.util.Base64;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+@State(Scope.Benchmark)
+@Warmup(iterations = 5, time = 2)
+@Measurement(iterations = 5, time = 2)
+@Fork(value = 2)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+public class Base64EncodeToString {
+
+    private byte[] input;
+
+    @Param({"10", "100", "1000", "10000"})
+    private int inputSize;
+
+    @Setup
+    public void setup() {
+        Random r = new Random(1123);
+        input = new byte[inputSize];
+        r.nextBytes(input);
+    }
+
+    @Benchmark
+    public String testEncodeToString() {
+        return Base64.getEncoder().encodeToString(input);
+    }
+}
+