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MySQL JDBC Type 4 driver
/*
Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
The MySQL Connector/J is licensed under the terms of the GPLv2
, like most MySQL Connectors.
There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
this software, see the FLOSS License Exception
.
This program is free software; you can redistribute it and/or modify it under the terms
of the GNU General Public License as published by the Free Software Foundation; version 2
of the License.
This program 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 for more details.
You should have received a copy of the GNU General Public License along with this
program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
Floor, Boston, MA 02110-1301 USA
*/
package com.mysql.jdbc;
import java.io.UnsupportedEncodingException;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
/**
* Converter for char[]->byte[] and byte[]->char[] for single-byte character
* sets.
*
* Much faster (5-6x) than the built-in solution that ships with the JVM, even
* with JDK-1.4.x and NewIo.
*
* @author Mark Matthews
*/
public class SingleByteCharsetConverter {
private static final int BYTE_RANGE = (1 + Byte.MAX_VALUE) - Byte.MIN_VALUE;
private static byte[] allBytes = new byte[BYTE_RANGE];
private static final Map CONVERTER_MAP = new HashMap();
private final static byte[] EMPTY_BYTE_ARRAY = new byte[0];
// The initial charToByteMap, with all char mappings mapped
// to (byte) '?', so that unknown characters are mapped to '?'
// instead of '\0' (which means end-of-string to MySQL).
private static byte[] unknownCharsMap = new byte[65536];
static {
for (int i = Byte.MIN_VALUE; i <= Byte.MAX_VALUE; i++) {
allBytes[i - Byte.MIN_VALUE] = (byte) i;
}
for (int i = 0; i < unknownCharsMap.length; i++) {
unknownCharsMap[i] = (byte) '?'; // use something 'sane' for
// unknown chars
}
}
// ~ Instance fields
// --------------------------------------------------------
/**
* Get a converter for the given encoding name
*
* @param encodingName
* the Java character encoding name
* @param conn
*
* @return a converter for the given encoding name
* @throws UnsupportedEncodingException
* if the character encoding is not supported
*/
public static synchronized SingleByteCharsetConverter getInstance(
String encodingName, Connection conn)
throws UnsupportedEncodingException, SQLException {
SingleByteCharsetConverter instance = CONVERTER_MAP
.get(encodingName);
if (instance == null) {
instance = initCharset(encodingName);
}
return instance;
}
/**
* Initialize the shared instance of a converter for the given character
* encoding.
*
* @param javaEncodingName
* the Java name for the character set to initialize
* @return a converter for the given character set
* @throws UnsupportedEncodingException
* if the character encoding is not supported
*/
public static SingleByteCharsetConverter initCharset(String javaEncodingName)
throws UnsupportedEncodingException, SQLException {
try {
if (CharsetMapping.isMultibyteCharset(javaEncodingName)) {
return null;
}
} catch (RuntimeException ex) {
SQLException sqlEx = SQLError.createSQLException(ex.toString(), SQLError.SQL_STATE_ILLEGAL_ARGUMENT, null);
sqlEx.initCause(ex);
throw sqlEx;
}
SingleByteCharsetConverter converter = new SingleByteCharsetConverter(
javaEncodingName);
CONVERTER_MAP.put(javaEncodingName, converter);
return converter;
}
// ~ Constructors
// -----------------------------------------------------------
/**
* Convert the byte buffer from startPos to a length of length to a string
* using the default platform encoding.
*
* @param buffer
* the bytes to convert
* @param startPos
* the index to start at
* @param length
* the number of bytes to convert
* @return the String representation of the given bytes
*/
public static String toStringDefaultEncoding(byte[] buffer, int startPos,
int length) {
return new String(buffer, startPos, length);
}
// ~ Methods
// ----------------------------------------------------------------
private char[] byteToChars = new char[BYTE_RANGE];
private byte[] charToByteMap = new byte[65536];
/**
* Prevent instantiation, called out of static method initCharset().
*
* @param encodingName
* a JVM character encoding
* @throws UnsupportedEncodingException
* if the JVM does not support the encoding
*/
private SingleByteCharsetConverter(String encodingName)
throws UnsupportedEncodingException {
String allBytesString = new String(allBytes, 0, BYTE_RANGE,
encodingName);
int allBytesLen = allBytesString.length();
System.arraycopy(unknownCharsMap, 0, this.charToByteMap, 0,
this.charToByteMap.length);
for (int i = 0; i < BYTE_RANGE && i < allBytesLen; i++) {
char c = allBytesString.charAt(i);
this.byteToChars[i] = c;
this.charToByteMap[c] = allBytes[i];
}
}
public final byte[] toBytes(char[] c) {
if (c == null) {
return null;
}
int length = c.length;
byte[] bytes = new byte[length];
for (int i = 0; i < length; i++) {
bytes[i] = this.charToByteMap[c[i]];
}
return bytes;
}
public final byte[] toBytesWrapped(char[] c, char beginWrap, char endWrap) {
if (c == null) {
return null;
}
int length = c.length + 2;
int charLength = c.length;
byte[] bytes = new byte[length];
bytes[0] = this.charToByteMap[beginWrap];
for (int i = 0; i < charLength; i++) {
bytes[i + 1] = this.charToByteMap[c[i]];
}
bytes[length - 1] = this.charToByteMap[endWrap];
return bytes;
}
public final byte[] toBytes(char[] chars, int offset, int length) {
if (chars == null) {
return null;
}
if (length == 0) {
return EMPTY_BYTE_ARRAY;
}
byte[] bytes = new byte[length];
for (int i = 0; (i < length); i++) {
bytes[i] = this.charToByteMap[chars[i + offset]];
}
return bytes;
}
/**
* Convert the given string to an array of bytes.
*
* @param s
* the String to convert
* @return the bytes that make up the String
*/
public final byte[] toBytes(String s) {
if (s == null) {
return null;
}
int length = s.length();
byte[] bytes = new byte[length];
for (int i = 0; i < length; i++) {
bytes[i] = this.charToByteMap[s.charAt(i)];
}
return bytes;
}
public final byte[] toBytesWrapped(String s, char beginWrap, char endWrap) {
if (s == null) {
return null;
}
int stringLength = s.length();
int length = stringLength + 2;
byte[] bytes = new byte[length];
bytes[0] = this.charToByteMap[beginWrap];
for (int i = 0; i < stringLength; i++) {
bytes[i + 1] = this.charToByteMap[s.charAt(i)];
}
bytes[length - 1] = this.charToByteMap[endWrap];
return bytes;
}
/**
* Convert the given string to an array of bytes.
*
* @param s
* the String to convert
* @param offset
* the offset to start at
* @param length
* length (max) to convert
*
* @return the bytes that make up the String
*/
public final byte[] toBytes(String s, int offset, int length) {
if (s == null) {
return null;
}
if (length == 0) {
return EMPTY_BYTE_ARRAY;
}
byte[] bytes = new byte[length];
for (int i = 0; (i < length); i++) {
char c = s.charAt(i + offset);
bytes[i] = this.charToByteMap[c];
}
return bytes;
}
/**
* Convert the byte buffer to a string using this instance's character
* encoding.
*
* @param buffer
* the bytes to convert to a String
* @return the converted String
*/
public final String toString(byte[] buffer) {
return toString(buffer, 0, buffer.length);
}
/**
* Convert the byte buffer from startPos to a length of length to a string
* using this instance's character encoding.
*
* @param buffer
* the bytes to convert
* @param startPos
* the index to start at
* @param length
* the number of bytes to convert
* @return the String representation of the given bytes
*/
public final String toString(byte[] buffer, int startPos, int length) {
char[] charArray = new char[length];
int readpoint = startPos;
for (int i = 0; i < length; i++) {
charArray[i] = this.byteToChars[buffer[readpoint] - Byte.MIN_VALUE];
readpoint++;
}
return new String(charArray);
}
}