forked from fanruan/design
李攀
8 years ago
3 changed files with 5 additions and 258 deletions
@ -1,256 +0,0 @@ |
|||||||
package com.fr.design.extra.ucenter; |
|
||||||
|
|
||||||
import java.io.*; |
|
||||||
|
|
||||||
/** |
|
||||||
* Created by lp on 2016/9/9. |
|
||||||
*/ |
|
||||||
public class Base64 { |
|
||||||
/** |
|
||||||
* returns an array of base64-encoded characters to represent the |
|
||||||
* passed data array. |
|
||||||
* |
|
||||||
* @param data the array of bytes to encode |
|
||||||
* @return base64-coded character array. |
|
||||||
*/ |
|
||||||
public static char[] encode(byte[] data) { |
|
||||||
char[] out = new char[((data.length + 2) / 3) * 4]; |
|
||||||
|
|
||||||
//
|
|
||||||
// 3 bytes encode to 4 chars. Output is always an even
|
|
||||||
// multiple of 4 characters.
|
|
||||||
//
|
|
||||||
for (int i = 0, index = 0; i < data.length; i += 3, index += 4) { |
|
||||||
boolean quad = false; |
|
||||||
boolean trip = false; |
|
||||||
|
|
||||||
int val = (0xFF & data[i]); |
|
||||||
val <<= 8; |
|
||||||
if ((i + 1) < data.length) { |
|
||||||
val |= (0xFF & data[i + 1]); |
|
||||||
trip = true; |
|
||||||
} |
|
||||||
val <<= 8; |
|
||||||
if ((i + 2) < data.length) { |
|
||||||
val |= (0xFF & data[i + 2]); |
|
||||||
quad = true; |
|
||||||
} |
|
||||||
out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)]; |
|
||||||
val >>= 6; |
|
||||||
out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)]; |
|
||||||
val >>= 6; |
|
||||||
out[index + 1] = alphabet[val & 0x3F]; |
|
||||||
val >>= 6; |
|
||||||
out[index + 0] = alphabet[val & 0x3F]; |
|
||||||
} |
|
||||||
return out; |
|
||||||
} |
|
||||||
|
|
||||||
/** |
|
||||||
* Decodes a BASE-64 encoded stream to recover the original |
|
||||||
* data. White space before and after will be trimmed away, |
|
||||||
* but no other manipulation of the input will be performed. |
|
||||||
* |
|
||||||
* As of version 1.2 this method will properly handle input |
|
||||||
* containing junk characters (newlines and the like) rather |
|
||||||
* than throwing an error. It does this by pre-parsing the |
|
||||||
* input and generating from that a count of VALID input |
|
||||||
* characters. |
|
||||||
**/ |
|
||||||
public static byte[] decode(char[] data) { |
|
||||||
// as our input could contain non-BASE64 data (newlines,
|
|
||||||
// whitespace of any sort, whatever) we must first adjust
|
|
||||||
// our count of USABLE data so that...
|
|
||||||
// (a) we don't misallocate the output array, and
|
|
||||||
// (b) think that we miscalculated our data length
|
|
||||||
// just because of extraneous throw-away junk
|
|
||||||
|
|
||||||
int tempLen = data.length; |
|
||||||
for (int ix = 0; ix < data.length; ix++) { |
|
||||||
if ((data[ix] > 255) || codes[data[ix]] < 0) |
|
||||||
--tempLen; // ignore non-valid chars and padding
|
|
||||||
} |
|
||||||
// calculate required length:
|
|
||||||
// -- 3 bytes for every 4 valid base64 chars
|
|
||||||
// -- plus 2 bytes if there are 3 extra base64 chars,
|
|
||||||
// or plus 1 byte if there are 2 extra.
|
|
||||||
|
|
||||||
int len = (tempLen / 4) * 3; |
|
||||||
if ((tempLen % 4) == 3) |
|
||||||
len += 2; |
|
||||||
if ((tempLen % 4) == 2) |
|
||||||
len += 1; |
|
||||||
|
|
||||||
byte[] out = new byte[len]; |
|
||||||
|
|
||||||
|
|
||||||
int shift = 0; // # of excess bits stored in accum
|
|
||||||
int accum = 0; // excess bits
|
|
||||||
int index = 0; |
|
||||||
|
|
||||||
// we now go through the entire array (NOT using the 'tempLen' value)
|
|
||||||
for (int ix = 0; ix < data.length; ix++) { |
|
||||||
int value = (data[ix] > 255) ? -1 : codes[data[ix]]; |
|
||||||
|
|
||||||
if (value >= 0)// skip over non-code
|
|
||||||
{ |
|
||||||
accum <<= 6; // bits shift up by 6 each time thru
|
|
||||||
shift += 6; // loop, with new bits being put in
|
|
||||||
accum |= value; // at the bottom.
|
|
||||||
if (shift >= 8)// whenever there are 8 or more shifted in,
|
|
||||||
{ |
|
||||||
shift -= 8; // write them out (from the top, leaving any
|
|
||||||
out[index++] = // excess at the bottom for next iteration.
|
|
||||||
(byte) ((accum >> shift) & 0xff); |
|
||||||
} |
|
||||||
} |
|
||||||
// we will also have skipped processing a padding null byte ('=') here;
|
|
||||||
// these are used ONLY for padding to an even length and do not legally
|
|
||||||
// occur as encoded data. for this reason we can ignore the fact that
|
|
||||||
// no index++ operation occurs in that special case: the out[] array is
|
|
||||||
// initialized to all-zero bytes to start with and that works to our
|
|
||||||
// advantage in this combination.
|
|
||||||
} |
|
||||||
|
|
||||||
// if there is STILL something wrong we just have to throw up now!
|
|
||||||
if (index != out.length) { |
|
||||||
throw new Error("Miscalculated data length (wrote " + |
|
||||||
index + " instead of " + out.length + ")"); |
|
||||||
} |
|
||||||
|
|
||||||
return out; |
|
||||||
} |
|
||||||
|
|
||||||
|
|
||||||
//
|
|
||||||
// code characters for values 0..63
|
|
||||||
//
|
|
||||||
private static char[] alphabet = |
|
||||||
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=".toCharArray(); |
|
||||||
|
|
||||||
//
|
|
||||||
// lookup table for converting base64 characters to value in range 0..63
|
|
||||||
//
|
|
||||||
private static byte[] codes = new byte[256]; |
|
||||||
|
|
||||||
static { |
|
||||||
for (int i = 0; i < 256; i++) |
|
||||||
codes[i] = -1; |
|
||||||
for (int i = 'A'; i <= 'Z'; i++) |
|
||||||
codes[i] = (byte) (i - 'A'); |
|
||||||
for (int i = 'a'; i <= 'z'; i++) |
|
||||||
codes[i] = (byte) (26 + i - 'a'); |
|
||||||
for (int i = '0'; i <= '9'; i++) |
|
||||||
codes[i] = (byte) (52 + i - '0'); |
|
||||||
codes['+'] = 62; |
|
||||||
codes['/'] = 63; |
|
||||||
} |
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
///////////////////////////////////////////////////
|
|
||||||
// remainder (main method and helper functions) is
|
|
||||||
// for testing purposes only, feel free to clip it.
|
|
||||||
///////////////////////////////////////////////////
|
|
||||||
|
|
||||||
public static void main(String[] args) { |
|
||||||
boolean decode = false; |
|
||||||
|
|
||||||
if (args.length == 0) { |
|
||||||
System.out.println("usage: java Base64 [-d[ecode]] filename"); |
|
||||||
System.exit(0); |
|
||||||
} |
|
||||||
for (int i = 0; i < args.length; i++) { |
|
||||||
if ("-decode".equalsIgnoreCase(args[i])) |
|
||||||
decode = true; |
|
||||||
else if ("-d".equalsIgnoreCase(args[i])) |
|
||||||
decode = true; |
|
||||||
} |
|
||||||
|
|
||||||
String filename = args[args.length - 1]; |
|
||||||
File file = new File(filename); |
|
||||||
if (!file.exists()) { |
|
||||||
System.out.println("Error: file '" + filename + "' doesn't exist!"); |
|
||||||
System.exit(0); |
|
||||||
} |
|
||||||
|
|
||||||
if (decode) { |
|
||||||
char[] encoded = readChars(file); |
|
||||||
byte[] decoded = decode(encoded); |
|
||||||
writeBytes(file, decoded); |
|
||||||
} |
|
||||||
else { |
|
||||||
byte[] decoded = readBytes(file); |
|
||||||
char[] encoded = encode(decoded); |
|
||||||
writeChars(file, encoded); |
|
||||||
} |
|
||||||
} |
|
||||||
|
|
||||||
private static byte[] readBytes(File file) { |
|
||||||
ByteArrayOutputStream baos = new ByteArrayOutputStream(); |
|
||||||
try { |
|
||||||
InputStream fis = new FileInputStream(file); |
|
||||||
InputStream is = new BufferedInputStream(fis); |
|
||||||
int count = 0; |
|
||||||
byte[] buf = new byte[16384]; |
|
||||||
while ((count = is.read(buf)) != -1) { |
|
||||||
if (count > 0) |
|
||||||
baos.write(buf, 0, count); |
|
||||||
} |
|
||||||
is.close(); |
|
||||||
} |
|
||||||
catch (Exception e) { |
|
||||||
e.printStackTrace(); |
|
||||||
} |
|
||||||
|
|
||||||
return baos.toByteArray(); |
|
||||||
} |
|
||||||
|
|
||||||
private static char[] readChars(File file) { |
|
||||||
CharArrayWriter caw = new CharArrayWriter(); |
|
||||||
try { |
|
||||||
Reader fr = new FileReader(file); |
|
||||||
Reader in = new BufferedReader(fr); |
|
||||||
int count = 0; |
|
||||||
char[] buf = new char[16384]; |
|
||||||
while ((count = in.read(buf)) != -1) { |
|
||||||
if (count > 0) |
|
||||||
caw.write(buf, 0, count); |
|
||||||
} |
|
||||||
in.close(); |
|
||||||
} |
|
||||||
catch (Exception e) { |
|
||||||
e.printStackTrace(); |
|
||||||
} |
|
||||||
|
|
||||||
return caw.toCharArray(); |
|
||||||
} |
|
||||||
|
|
||||||
private static void writeBytes(File file, byte[] data) { |
|
||||||
try { |
|
||||||
OutputStream fos = new FileOutputStream(file); |
|
||||||
OutputStream os = new BufferedOutputStream(fos); |
|
||||||
os.write(data); |
|
||||||
os.close(); |
|
||||||
} |
|
||||||
catch (Exception e) { |
|
||||||
e.printStackTrace(); |
|
||||||
} |
|
||||||
} |
|
||||||
|
|
||||||
private static void writeChars(File file, char[] data) { |
|
||||||
try { |
|
||||||
Writer fos = new FileWriter(file); |
|
||||||
Writer os = new BufferedWriter(fos); |
|
||||||
os.write(data); |
|
||||||
os.close(); |
|
||||||
} |
|
||||||
catch (Exception e) { |
|
||||||
e.printStackTrace(); |
|
||||||
} |
|
||||||
} |
|
||||||
///////////////////////////////////////////////////
|
|
||||||
// end of test code.
|
|
||||||
///////////////////////////////////////////////////
|
|
||||||
} |
|
Loading…
Reference in new issue