From b5d2fc84d781d32d4d3369a4791de3733ee9d42d Mon Sep 17 00:00:00 2001
From: Andrei Selkin <andreyselkin@gmail.com>
Date: Wed, 13 Apr 2016 16:39:08 +0300
Subject: [PATCH] Pull #3093: Use DatatypeConverter#printHexBinary to convert
 byte array to hex String in PropertyCacheFile (#3093)

---
 config/import-control.xml                     |  1 +
 .../tools/checkstyle/PropertyCacheFile.java   | 32 ++-----------------
 2 files changed, 4 insertions(+), 29 deletions(-)

diff --git a/config/import-control.xml b/config/import-control.xml
index df7ae9e87..ea2b6cb13 100644
--- a/config/import-control.xml
+++ b/config/import-control.xml
@@ -24,6 +24,7 @@
   <!-- The local ones -->
   <allow class="java.security.MessageDigest" local-only="true"/>
   <allow class="java.security.NoSuchAlgorithmException" local-only="true"/>
+  <allow class="javax.xml.bind.DatatypeConverter" local-only="true"/>
   <allow pkg="com.puppycrawl.tools.checkstyle.grammars" local-only="true"/>
   <allow pkg="org.apache.commons.cli" local-only="true"/>
 
diff --git a/src/main/java/com/puppycrawl/tools/checkstyle/PropertyCacheFile.java b/src/main/java/com/puppycrawl/tools/checkstyle/PropertyCacheFile.java
index 1308d5e42..068654827 100644
--- a/src/main/java/com/puppycrawl/tools/checkstyle/PropertyCacheFile.java
+++ b/src/main/java/com/puppycrawl/tools/checkstyle/PropertyCacheFile.java
@@ -36,6 +36,8 @@ import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.Properties;
 
+import javax.xml.bind.DatatypeConverter;
+
 import com.google.common.io.Closeables;
 import com.google.common.io.Flushables;
 import com.puppycrawl.tools.checkstyle.api.Configuration;
@@ -62,18 +64,6 @@ final class PropertyCacheFile {
      */
     private static final String CONFIG_HASH_KEY = "configuration*?";
 
-    /** Hex digits. */
-    private static final char[] HEX_CHARS = {
-        '0', '1', '2', '3', '4', '5', '6', '7',
-        '8', '9', 'A', 'B', 'C', 'D', 'E', 'F',
-    };
-
-    /** Mask for last byte. */
-    private static final int MASK_0X0F = 0x0F;
-
-    /** Bit shift. */
-    private static final int SHIFT_4 = 4;
-
     /** The details on files. **/
     private final Properties details = new Properties();
 
@@ -221,27 +211,11 @@ final class PropertyCacheFile {
             final MessageDigest digest = MessageDigest.getInstance("SHA-1");
             digest.update(outputStream.toByteArray());
 
-            return hexEncode(digest.digest());
+            return DatatypeConverter.printHexBinary(digest.digest());
         }
         catch (final IOException | NoSuchAlgorithmException ex) {
             // rethrow as unchecked exception
             throw new IllegalStateException("Unable to calculate hashcode.", ex);
         }
     }
-
-    /**
-     * Hex-encodes a byte array.
-     * @param byteArray the byte array
-     * @return hex encoding of {@code byteArray}
-     */
-    private static String hexEncode(byte... byteArray) {
-        final StringBuilder buf = new StringBuilder(2 * byteArray.length);
-        for (final byte b : byteArray) {
-            final int low = b & MASK_0X0F;
-            final int high = b >> SHIFT_4 & MASK_0X0F;
-            buf.append(HEX_CHARS[high]);
-            buf.append(HEX_CHARS[low]);
-        }
-        return buf.toString();
-    }
 }