Add base 64 encoding/decoding extensions.

api/current.txt

@@ -450,6 +450,14 @@ package androidx.core.util {
     method @RequiresApi(17) public static void writeText(android.util.AtomicFile, String text, java.nio.charset.Charset charset = "Charsets.UTF_8");
   }
 
+  public final class Base64Kt {
+    ctor public Base64Kt();
+    method public static byte[] decodeBase64(String, int flags = "Base64.DEFAULT");
+    method public static byte[] decodeBase64(byte[], int flags = "Base64.DEFAULT", int offset = "0", int length = "size");
+    method public static String encodeBase64(String, int flags = "Base64.DEFAULT", java.nio.charset.Charset charset = "UTF_8");
+    method public static String encodeBase64(byte[], int flags = "Base64.DEFAULT", int offset = "0", int length = "size");
+  }
+
   public final class HalfKt {
     ctor public HalfKt();
     method @RequiresApi(26) public static android.util.Half toHalf(short);

src/androidTest/java/androidx/core/util/Base64Test.kt

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.core.util
+
+import android.util.Base64.NO_WRAP
+import org.junit.Assert.assertArrayEquals
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import kotlin.text.Charsets.UTF_16BE
+
+class Base64Test {
+    @Test fun encodeFromString() {
+        val result = "a\uD83C\uDF69c".encodeBase64()
+        assertEquals("YfCfjalj\n", result)
+    }
+
+    @Test fun encodeFromStringWithFlags() {
+        val result = "a\uD83C\uDF69c".encodeBase64(flags = NO_WRAP)
+        assertEquals("YfCfjalj", result)
+    }
+
+    @Test fun encodeFromStringWithCharset() {
+        val result = "a\uD83C\uDF69c".encodeBase64(charset = UTF_16BE)
+        assertEquals("AGHYPN9pAGM=\n", result)
+    }
+
+    @Test fun encodeFromByteArray() {
+        val result = "a\uD83C\uDF69c".toByteArray().encodeBase64()
+        assertEquals("YfCfjalj\n", result)
+    }
+
+    @Test fun encodeFromByteArrayFlags() {
+        val result = "a\uD83C\uDF69c".toByteArray().encodeBase64(flags = NO_WRAP)
+        assertEquals("YfCfjalj", result)
+    }
+
+    @Test fun encodeFromByteArrayOffsetAndLength() {
+        val result = "a\uD83C\uDF69c".toByteArray().encodeBase64(offset = 1, length = 4)
+        assertEquals("8J+NqQ==\n", result)
+    }
+
+    @Test fun decodeFromString() {
+        val result = "YfCfjalj\n".decodeBase64()
+        assertArrayEquals("a\uD83C\uDF69c".toByteArray(), result)
+    }
+
+    @Test fun decodeFromStringWithFlags() {
+        val result = "YfCfjalj".decodeBase64(flags = NO_WRAP)
+        assertArrayEquals("a\uD83C\uDF69c".toByteArray(), result)
+    }
+
+    @Test fun decodeFromByteArray() {
+        val result = "YfCfjalj\n".toByteArray().decodeBase64()
+        assertArrayEquals("a\uD83C\uDF69c".toByteArray(), result)
+    }
+
+    @Test fun decodeFromByteArrayWithFlags() {
+        val result = "YfCfjalj".toByteArray().decodeBase64(flags = NO_WRAP)
+        assertArrayEquals("a\uD83C\uDF69c".toByteArray(), result)
+    }
+
+    @Test fun decodeFromByteArrayOffsetAndLength() {
+        val result = "xx8J+NqQ==xx".toByteArray().decodeBase64(offset = 2, length = 8)
+        assertArrayEquals("\uD83C\uDF69".toByteArray(), result)
+    }
+}

src/main/java/androidx/core/util/Base64.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@file:Suppress("NOTHING_TO_INLINE")
+
+package androidx.core.util
+
+import android.util.Base64
+import java.nio.charset.Charset
+import kotlin.text.Charsets.US_ASCII
+import kotlin.text.Charsets.UTF_8
+
+/**
+ * Encode this [String] to its base-64 ASCII string representation.
+ *
+ * @see Base64.encode
+ */
+inline fun String.encodeBase64(
+    flags: Int = Base64.DEFAULT,
+    charset: Charset = UTF_8
+): String = Base64.encode(toByteArray(charset), flags).toString(US_ASCII)
+
+/**
+ * Encode this [ByteArray] to its base-64 ASCII string representation.
+ *
+ * @see Base64.encode
+ */
+inline fun ByteArray.encodeBase64(
+    flags: Int = Base64.DEFAULT,
+    offset: Int = 0,
+    length: Int = size
+): String = Base64.encode(this, offset, length, flags).toString(US_ASCII)
+
+/**
+ * Decode this base-64 encoded ASCII [String] to its original bytes.
+ *
+ * @see Base64.decode
+ */
+inline fun String.decodeBase64(
+    flags: Int = Base64.DEFAULT
+): ByteArray = Base64.decode(toByteArray(US_ASCII), flags)
+
+/**
+ * Decode this base-64 encoded [ByteArray] to its original bytes.
+ *
+ * @see Base64.decode
+ */
+inline fun ByteArray.decodeBase64(
+    flags: Int = Base64.DEFAULT,
+    offset: Int = 0,
+    length: Int = size
+): ByteArray = Base64.decode(this, offset, length, flags)