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fastdfs-client-java/src/org/csource/common/Base64.java

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2014-12-07 11:24:05 +08:00
package org.csource.common;
import java.io.IOException;
/**
* Freeware from:
* Roedy Green
* Canadian Mind Products
* #327 - 964 Heywood Avenue
* Victoria, BC Canada V8V 2Y5
* tel:(250) 361-9093
* mailto:roedy@mindprod.com
*/
/**
* Encode arbitrary binary into printable ASCII using BASE64 encoding.
* very loosely based on the Base64 Reader by
* Dr. Mark Thornton
* Optrak Distribution Software Ltd.
* http://www.optrak.co.uk
* and Kevin Kelley's http://www.ruralnet.net/~kelley/java/Base64.java
*
* Base64 is a way of encoding 8-bit characters using only ASCII printable
* characters similar to UUENCODE. UUENCODE includes a filename where BASE64 does not.
* The spec is described in RFC 2045. Base64 is a scheme where
* 3 bytes are concatenated, then split to form 4 groups of 6-bits each; and
* each 6-bits gets translated to an encoded printable ASCII character, via a
* table lookup. An encoded string is therefore longer than the original by
* about 1/3. The "=" character is used to pad the end. Base64 is used,
* among other things, to encode the user:password string in an
* Authorization: header for HTTP. Don't confuse Base64 with
* x-www-form-urlencoded which is handled by
* Java.net.URLEncoder.encode/decode
* If you don't like this code, there is another implementation at http://www.ruffboy.com/download.htm
* Sun has an undocumented method called sun.misc.Base64Encoder.encode.
* You could use hex, simpler to code, but not as compact.
*
* If you wanted to encode a giant file, you could do it in large chunks that
* are even multiples of 3 bytes, except for the last chunk, and append the outputs.
*
* To encode a string, rather than binary data java.net.URLEncoder may be better. See
* printable characters in the Java glossary for a discussion of the differences.
*
* version 1.4 2002 February 15 -- correct bugs with uneven line lengths,
* allow you to configure line separator.
* now need Base64 object and instance methods.
* new mailing address.
* version 1.3 2000 September 12 -- fix problems with estimating output length in encode
* version 1.2 2000 September 09 -- now handles decode as well.
* version 1.1 1999 December 04 -- more symmetrical encoding algorithm.
* more accurate StringBuffer allocation size.
* version 1.0 1999 December 03 -- posted in comp.lang.java.programmer.
* Futures Streams or files.
*/
public class Base64
{
/**
* how we separate lines, e.g. \n, \r\n, \r etc.
*/
private String lineSeparator = System.getProperty( "line.separator" );
/**
* max chars per line, excluding lineSeparator. A multiple of 4.
*/
private int lineLength = 72;
private char[] valueToChar = new char[64];
/**
* binary value encoded by a given letter of the alphabet 0..63
*/
private int[] charToValue = new int[256];
private int[] charToPad = new int[4];
/* constructor */
public Base64()
{
this.init('+', '/', '=');
}
/* constructor */
public Base64(char chPlus, char chSplash, char chPad, int lineLength)
{
this.init(chPlus, chSplash, chPad);
this.lineLength = lineLength;
}
public Base64(int lineLength)
{
this.lineLength = lineLength;
}
/* initialise defaultValueToChar and defaultCharToValue tables */
private void init(char chPlus, char chSplash, char chPad)
{
int index = 0;
// build translate this.valueToChar table only once.
// 0..25 -> 'A'..'Z'
for ( int i='A'; i<='Z'; i++) {
this.valueToChar[index++] = (char)i;
}
// 26..51 -> 'a'..'z'
for ( int i='a'; i<='z'; i++ ) {
this.valueToChar[index++] = (char)i;
}
// 52..61 -> '0'..'9'
for ( int i='0'; i<='9'; i++) {
this.valueToChar[index++] = (char)i;
}
this.valueToChar[index++] = chPlus;
this.valueToChar[index++] = chSplash;
// build translate defaultCharToValue table only once.
for ( int i=0; i<256; i++ )
{
this.charToValue[i] = IGNORE; // default is to ignore
}
for ( int i=0; i<64; i++ )
{
this.charToValue[this.valueToChar[i]] = i;
}
this.charToValue[chPad] = PAD;
java.util.Arrays.fill(this.charToPad, chPad);
}
/**
* Encode an arbitrary array of bytes as Base64 printable ASCII.
* It will be broken into lines of 72 chars each. The last line is not
* terminated with a line separator.
* The output will always have an even multiple of data characters,
* exclusive of \n. It is padded out with =.
*/
public String encode(byte[] b) throws IOException
{
// Each group or partial group of 3 bytes becomes four chars
// covered quotient
int outputLength = ((b.length + 2) / 3) * 4;
// account for trailing newlines, on all but the very last line
if ( lineLength != 0 )
{
int lines = ( outputLength + lineLength -1 ) / lineLength - 1;
if ( lines > 0 )
{
outputLength += lines * lineSeparator.length();
}
}
// must be local for recursion to work.
StringBuffer sb = new StringBuffer( outputLength );
// must be local for recursion to work.
int linePos = 0;
// first deal with even multiples of 3 bytes.
int len = (b.length / 3) * 3;
int leftover = b.length - len;
for ( int i=0; i<len; i+=3 )
{
// Start a new line if next 4 chars won't fit on the current line
// We can't encapsulete the following code since the variable need to
// be local to this incarnation of encode.
linePos += 4;
if ( linePos > lineLength )
{
if ( lineLength != 0 )
{
sb.append(lineSeparator);
}
linePos = 4;
}
// get next three bytes in unsigned form lined up,
// in big-endian order
int combined = b[i+0] & 0xff;
combined <<= 8;
combined |= b[i+1] & 0xff;
combined <<= 8;
combined |= b[i+2] & 0xff;
// break those 24 bits into a 4 groups of 6 bits,
// working LSB to MSB.
int c3 = combined & 0x3f;
combined >>>= 6;
int c2 = combined & 0x3f;
combined >>>= 6;
int c1 = combined & 0x3f;
combined >>>= 6;
int c0 = combined & 0x3f;
// Translate into the equivalent alpha character
// emitting them in big-endian order.
sb.append( valueToChar[c0]);
sb.append( valueToChar[c1]);
sb.append( valueToChar[c2]);
sb.append( valueToChar[c3]);
}
// deal with leftover bytes
switch ( leftover )
{
case 0:
default:
// nothing to do
break;
case 1:
// One leftover byte generates xx==
// Start a new line if next 4 chars won't fit on the current line
linePos += 4;
if ( linePos > lineLength )
{
if ( lineLength != 0 )
{
sb.append(lineSeparator);
}
linePos = 4;
}
// Handle this recursively with a faked complete triple.
// Throw away last two chars and replace with ==
sb.append(encode(new byte[] {b[len], 0, 0}
).substring(0,2));
sb.append("==");
break;
case 2:
// Two leftover bytes generates xxx=
// Start a new line if next 4 chars won't fit on the current line
linePos += 4;
if ( linePos > lineLength )
{
if ( lineLength != 0 )
{
sb.append(lineSeparator);
}
linePos = 4;
}
// Handle this recursively with a faked complete triple.
// Throw away last char and replace with =
sb.append(encode(new byte[] {b[len], b[len+1], 0}
).substring(0,3));
sb.append("=");
break;
} // end switch;
if ( outputLength != sb.length() )
{
System.out.println("oops: minor program flaw: output length mis-estimated");
System.out.println("estimate:" + outputLength);
System.out.println("actual:" + sb.length());
}
return sb.toString();
}// end encode
/**
* decode a well-formed complete Base64 string back into an array of bytes.
* It must have an even multiple of 4 data characters (not counting \n),
* padded out with = as needed.
*/
public byte[] decodeAuto( String s) {
int nRemain = s.length() % 4;
if (nRemain == 0) {
return this.decode(s);
} else {
return this.decode(s + new String(this.charToPad, 0, 4 - nRemain));
}
}
/**
* decode a well-formed complete Base64 string back into an array of bytes.
* It must have an even multiple of 4 data characters (not counting \n),
* padded out with = as needed.
*/
public byte[] decode( String s)
{
// estimate worst case size of output array, no embedded newlines.
byte[] b = new byte[(s.length() / 4) * 3];
// tracks where we are in a cycle of 4 input chars.
int cycle = 0;
// where we combine 4 groups of 6 bits and take apart as 3 groups of 8.
int combined = 0;
// how many bytes we have prepared.
int j = 0;
// will be an even multiple of 4 chars, plus some embedded \n
int len = s.length();
int dummies = 0;
for ( int i=0; i<len; i++ )
{
int c = s.charAt(i);
int value = (c <= 255) ? charToValue[c] : IGNORE;
// there are two magic values PAD (=) and IGNORE.
switch ( value )
{
case IGNORE:
// e.g. \n, just ignore it.
break;
case PAD:
value = 0;
dummies++;
// fallthrough
default:
/* regular value character */
switch ( cycle )
{
case 0:
combined = value;
cycle = 1;
break;
case 1:
combined <<= 6;
combined |= value;
cycle = 2;
break;
case 2:
combined <<= 6;
combined |= value;
cycle = 3;
break;
case 3:
combined <<= 6;
combined |= value;
// we have just completed a cycle of 4 chars.
// the four 6-bit values are in combined in big-endian order
// peel them off 8 bits at a time working lsb to msb
// to get our original 3 8-bit bytes back
b[j+2] = (byte)combined;
combined >>>= 8;
b[j+1] = (byte)combined;
combined >>>= 8;
b[j] = (byte)combined;
j += 3;
cycle = 0;
break;
}
break;
}
} // end for
if ( cycle != 0 )
{
throw new ArrayIndexOutOfBoundsException ("Input to decode not an even multiple of 4 characters; pad with =.");
}
j -= dummies;
if ( b.length != j )
{
byte[] b2 = new byte[j];
System.arraycopy(b, 0, b2, 0, j);
b = b2;
}
return b;
}// end decode
/**
* determines how long the lines are that are generated by encode.
* Ignored by decode.
* @param length 0 means no newlines inserted. Must be a multiple of 4.
*/
public void setLineLength(int length)
{
this.lineLength = (length/4) * 4;
}
/**
* How lines are separated.
* Ignored by decode.
* @param lineSeparator may be "" but not null.
* Usually contains only a combination of chars \n and \r.
* Could be any chars not in set A-Z a-z 0-9 + /.
*/
public void setLineSeparator(String lineSeparator)
{
this.lineSeparator = lineSeparator;
}
/**
* Marker value for chars we just ignore, e.g. \n \r high ascii
*/
static final int IGNORE = -1;
/**
* Marker for = trailing pad
*/
static final int PAD = -2;
/**
* used to disable test driver
*/
private static final boolean debug = true;
/**
* debug display array
*/
public static void show (byte[] b)
{
int count = 0;
int rows = 0;
for ( int i=0; i<b.length; i++ )
{
if(count == 8)
{
System.out.print(" ");
}
else if(count == 16)
{
System.out.println("");
count = 0;
continue;
}
System.out.print( Integer.toHexString(b[i] & 0xFF).toUpperCase() + " ");
count ++;
}
System.out.println();
}
/**
* debug display array
*/
public static void display (byte[] b)
{
for ( int i=0; i<b.length; i++ )
{
System.out.print( (char)b[i]);
}
System.out.println();
}
/**
* test driver
*/
public static void main(String[] args)
{
test();
System.exit(1);
if ( debug )
{
try
{
Base64 b64 = new Base64();
String str = "agfrtu<EFBFBD><EFBFBD>etʲ1234<EFBFBD>ٴ<EFBFBD>erty<EFBFBD><EFBFBD>234<EFBFBD><EFBFBD><EFBFBD><EFBFBD>2344ʲ<EFBFBD><EFBFBD>";
String str64 = "";
//encode
str64 = b64.encode(str.getBytes());
System.out.println(str64);
//decode
byte[] theBytes = b64.decode(str64);
show(theBytes);
String rst = new String(theBytes);
System.out.println(rst);
System.out.println(str);
}
catch(Exception e)
{
e.printStackTrace();
}
//getBytes(String charsetName);
/*
byte[] a = { (byte)0xfc, (byte)0x0f, (byte)0xc0};
byte[] b = { (byte)0x03, (byte)0xf0, (byte)0x3f};
byte[] c = { (byte)0x00, (byte)0x00, (byte)0x00};
byte[] d = { (byte)0xff, (byte)0xff, (byte)0xff};
byte[] e = { (byte)0xfc, (byte)0x0f, (byte)0xc0, (byte)1};
byte[] f = { (byte)0xfc, (byte)0x0f, (byte)0xc0, (byte)1, (byte)2};
byte[] g = { (byte)0xfc, (byte)0x0f, (byte)0xc0, (byte)1, (byte)2, (byte)3};
byte[] h = "AAAAAAAAAAB".getBytes();
show(a);
show(b);
show(c);
show(d);
show(e);
show(f);
show(g);
show(h);
Base64 b64 = new Base64();
show(b64.decode(b64.encode(a)));
show(b64.decode(b64.encode(b)));
show(b64.decode(b64.encode(c)));
show(b64.decode(b64.encode(d)));
show(b64.decode(b64.encode(e)));
show(b64.decode(b64.encode(f)));
show(b64.decode(b64.encode(g)));
show(b64.decode(b64.encode(h)));
b64.setLineLength(8);
show((b64.encode(h)).getBytes());
*/
}
}// end main
public static void test()
{
try
{
Base64 b64 = new Base64();
//encode
//str64 = b64.encode(str.getBytes());
//System.out.println(str64);
String str64 = "CwUEFYoAAAADjQMC7ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267ELJiY6w05267EI=";
//decode
byte[] theBytes = b64.decode(str64);
show(theBytes);
}
catch(Exception e)
{
e.printStackTrace();
}
}
} // end Base64
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