refactor && enhance mysql sql parser support

src/main/java/com/alibaba/druid/util/HexBin.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 1999-2002,2004 The Apache Software Foundation.
+ * 
+ * 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 com.alibaba.druid.util;
+
+
+/**
+ * format validation
+ *
+ * This class encodes/decodes hexadecimal data
+ * 
+ * @xerces.internal  
+ * 
+ * @author Jeffrey Rodriguez
+ * @version $Id: HexBin.java,v 1.4 2007/07/19 04:38:32 ofung Exp $
+ */
+public final class  HexBin {
+    static private final int  BASELENGTH   = 128;
+    static private final int  LOOKUPLENGTH = 16;
+    static final private byte [] hexNumberTable    = new byte[BASELENGTH];
+    static final private char [] lookUpHexAlphabet = new char[LOOKUPLENGTH];
+
+
+    static {
+        for (int i = 0; i < BASELENGTH; i++ ) {
+            hexNumberTable[i] = -1;
+        }
+        for ( int i = '9'; i >= '0'; i--) {
+            hexNumberTable[i] = (byte) (i-'0');
+        }
+        for ( int i = 'F'; i>= 'A'; i--) {
+            hexNumberTable[i] = (byte) ( i-'A' + 10 );
+        }
+        for ( int i = 'f'; i>= 'a'; i--) {
+           hexNumberTable[i] = (byte) ( i-'a' + 10 );
+        }
+
+        for(int i = 0; i<10; i++ ) {
+            lookUpHexAlphabet[i] = (char)('0'+i);
+        }
+        for(int i = 10; i<=15; i++ ) {
+            lookUpHexAlphabet[i] = (char)('A'+i -10);
+        }
+    }
+
+    /**
+     * Encode a byte array to hex string
+     *
+     * @param binaryData array of byte to encode
+     * @return return encoded string
+     */
+    static public String encode(byte[] binaryData) {
+        if (binaryData == null)
+            return null;
+        int lengthData   = binaryData.length;
+        int lengthEncode = lengthData * 2;
+        char[] encodedData = new char[lengthEncode];
+        int temp;
+        for (int i = 0; i < lengthData; i++) {
+            temp = binaryData[i];
+            if (temp < 0)
+                temp += 256;
+            encodedData[i*2] = lookUpHexAlphabet[temp >> 4];
+            encodedData[i*2+1] = lookUpHexAlphabet[temp & 0xf];
+        }
+        return new String(encodedData);
+    }
+
+    /**
+     * Decode hex string to a byte array
+     *
+     * @param encoded encoded string
+     * @return return array of byte to encode
+     */
+    static public byte[] decode(String encoded) {
+        if (encoded == null)
+            return null;
+        int lengthData = encoded.length();
+        if (lengthData % 2 != 0)
+            return null;
+
+        char[] binaryData = encoded.toCharArray();
+        int lengthDecode = lengthData / 2;
+        byte[] decodedData = new byte[lengthDecode];
+        byte temp1, temp2;
+        char tempChar;
+        for( int i = 0; i<lengthDecode; i++ ){
+            tempChar = binaryData[i*2];
+            temp1 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
+            if (temp1 == -1)
+                return null;
+            tempChar = binaryData[i*2+1];
+            temp2 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
+            if (temp2 == -1)
+                return null;
+            decodedData[i] = (byte)((temp1 << 4) | temp2);
+        }
+        return decodedData;
+    }
+}