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io.polaris.core.codec.Base64Encoder Maven / Gradle / Ivy
package io.polaris.core.codec;
import java.io.IOException;
import java.io.OutputStream;
/**
* @author Qt
* @since 1.8
*/
public class Base64Encoder implements Encoder {
protected final byte[] encodingTable =
{
(byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G',
(byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
(byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U',
(byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
(byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g',
(byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n',
(byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u',
(byte) 'v',
(byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z',
(byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6',
(byte) '7', (byte) '8', (byte) '9',
(byte) '+', (byte) '/'
};
protected byte padding = (byte) '=';
/*
* set up the decoding table.
*/
protected final byte[] decodingTable = new byte[128];
protected void initialiseDecodingTable() {
for (int i = 0; i < decodingTable.length; i++) {
decodingTable[i] = (byte) 0xff;
}
for (int i = 0; i < encodingTable.length; i++) {
decodingTable[encodingTable[i]] = (byte) i;
}
}
public Base64Encoder() {
initialiseDecodingTable();
}
public int encode(byte[] inBuf, int inOff, int inLen, byte[] outBuf, int outOff) throws IOException {
int inPos = inOff;
int inEnd = inOff + inLen - 2;
int outPos = outOff;
while (inPos < inEnd) {
int a1 = inBuf[inPos++];
int a2 = inBuf[inPos++] & 0xFF;
int a3 = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 2) & 0x3F];
outBuf[outPos++] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3F];
outBuf[outPos++] = encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3F];
outBuf[outPos++] = encodingTable[a3 & 0x3F];
}
switch (inLen - (inPos - inOff)) {
case 1: {
int a1 = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 2) & 0x3F];
outBuf[outPos++] = encodingTable[(a1 << 4) & 0x3F];
outBuf[outPos++] = padding;
outBuf[outPos++] = padding;
break;
}
case 2: {
int a1 = inBuf[inPos++] & 0xFF;
int a2 = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 2) & 0x3F];
outBuf[outPos++] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3F];
outBuf[outPos++] = encodingTable[(a2 << 2) & 0x3F];
outBuf[outPos++] = padding;
break;
}
}
return outPos - outOff;
}
@Override
public int getEncodedLength(int inputLength) {
return (inputLength + 2) / 3 * 4;
}
@Override
public int getMaxDecodedLength(int inputLength) {
return inputLength / 4 * 3;
}
/**
* encode the input data producing a base 64 output stream.
*
* @return the number of bytes produced.
*/
@Override
public int encode(byte[] buf, int off, int len, OutputStream out)
throws IOException {
if (len < 0) {
return 0;
}
byte[] tmp = new byte[72];
int remaining = len;
while (remaining > 0) {
int inLen = Math.min(54, remaining);
int outLen = encode(buf, off, inLen, tmp, 0);
out.write(tmp, 0, outLen);
off += inLen;
remaining -= inLen;
}
return (len + 2) / 3 * 4;
}
private boolean ignore(
char c) {
return (c == '\n' || c == '\r' || c == '\t' || c == ' ');
}
/**
* decode the base 64 encoded byte data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
@Override
public int decode(
byte[] data,
int off,
int length,
OutputStream out)
throws IOException {
byte b1, b2, b3, b4;
byte[] outBuffer = new byte[54]; // S/MIME standard
int bufOff = 0;
int outLen = 0;
int end = off + length;
while (end > off) {
if (!ignore((char) data[end - 1])) {
break;
}
end--;
}
// empty data!
if (end == 0) {
return 0;
}
int i = 0;
int finish = end;
while (finish > off && i != 4) {
if (!ignore((char) data[finish - 1])) {
i++;
}
finish--;
}
i = nextI(data, off, finish);
while (i < finish) {
b1 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b2 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b3 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b4 = decodingTable[data[i++]];
if ((b1 | b2 | b3 | b4) < 0) {
throw new IOException("invalid characters encountered in base64 data");
}
outBuffer[bufOff++] = (byte) ((b1 << 2) | (b2 >> 4));
outBuffer[bufOff++] = (byte) ((b2 << 4) | (b3 >> 2));
outBuffer[bufOff++] = (byte) ((b3 << 6) | b4);
if (bufOff == outBuffer.length) {
out.write(outBuffer);
bufOff = 0;
}
outLen += 3;
i = nextI(data, i, finish);
}
if (bufOff > 0) {
out.write(outBuffer, 0, bufOff);
}
int e0 = nextI(data, i, end);
int e1 = nextI(data, e0 + 1, end);
int e2 = nextI(data, e1 + 1, end);
int e3 = nextI(data, e2 + 1, end);
outLen += decodeLastBlock(out, (char) data[e0], (char) data[e1], (char) data[e2], (char) data[e3]);
return outLen;
}
private int nextI(byte[] data, int i, int finish) {
while ((i < finish) && ignore((char) data[i])) {
i++;
}
return i;
}
/**
* decode the base 64 encoded String data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
@Override
public int decode(
String data,
OutputStream out)
throws IOException {
byte b1, b2, b3, b4;
byte[] outBuffer = new byte[54]; // S/MIME standard
int bufOff = 0;
int length = 0;
int end = data.length();
while (end > 0) {
if (!ignore(data.charAt(end - 1))) {
break;
}
end--;
}
// empty data!
if (end == 0) {
return 0;
}
int i = 0;
int finish = end;
while (finish > 0 && i != 4) {
if (!ignore(data.charAt(finish - 1))) {
i++;
}
finish--;
}
i = nextI(data, 0, finish);
while (i < finish) {
b1 = decodingTable[data.charAt(i++)];
i = nextI(data, i, finish);
b2 = decodingTable[data.charAt(i++)];
i = nextI(data, i, finish);
b3 = decodingTable[data.charAt(i++)];
i = nextI(data, i, finish);
b4 = decodingTable[data.charAt(i++)];
if ((b1 | b2 | b3 | b4) < 0) {
throw new IOException("invalid characters encountered in base64 data");
}
outBuffer[bufOff++] = (byte) ((b1 << 2) | (b2 >> 4));
outBuffer[bufOff++] = (byte) ((b2 << 4) | (b3 >> 2));
outBuffer[bufOff++] = (byte) ((b3 << 6) | b4);
length += 3;
if (bufOff == outBuffer.length) {
out.write(outBuffer);
bufOff = 0;
}
i = nextI(data, i, finish);
}
if (bufOff > 0) {
out.write(outBuffer, 0, bufOff);
}
int e0 = nextI(data, i, end);
int e1 = nextI(data, e0 + 1, end);
int e2 = nextI(data, e1 + 1, end);
int e3 = nextI(data, e2 + 1, end);
length += decodeLastBlock(out, data.charAt(e0), data.charAt(e1), data.charAt(e2), data.charAt(e3));
return length;
}
private int decodeLastBlock(OutputStream out, char c1, char c2, char c3, char c4)
throws IOException {
byte b1, b2, b3, b4;
if (c3 == padding) {
if (c4 != padding) {
throw new IOException("invalid characters encountered at end of base64 data");
}
b1 = decodingTable[c1];
b2 = decodingTable[c2];
if ((b1 | b2) < 0) {
throw new IOException("invalid characters encountered at end of base64 data");
}
out.write((b1 << 2) | (b2 >> 4));
return 1;
} else if (c4 == padding) {
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
if ((b1 | b2 | b3) < 0) {
throw new IOException("invalid characters encountered at end of base64 data");
}
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
return 2;
} else {
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
b4 = decodingTable[c4];
if ((b1 | b2 | b3 | b4) < 0) {
throw new IOException("invalid characters encountered at end of base64 data");
}
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
out.write((b3 << 6) | b4);
return 3;
}
}
private int nextI(String data, int i, int finish) {
while ((i < finish) && ignore(data.charAt(i))) {
i++;
}
return i;
}
}
