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/*
* Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
* All rights reserved.
*/
package com.sun.faces.io;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;
/**
* Provides a mechanism to accept and Base64 encode bytes into
* chars which will be flushed to the provided writer as the
* internal buffer fills.
*/
public class Base64OutputStreamWriter extends OutputStream {
/**
* The buffer where data is stored.
*/
private byte[] buf;
/**
* The Base64 encoded bytes as chars; essentially the output
* buffer
*/
private char[] chars;
/**
* The number of valid bytes in the buffer.
*/
private int count;
/**
* The current position within chars
*/
private int encCount;
/**
*
Tracks the total number of characters written.
*/
private int totalCharsWritten;
/**
* The writer we'll flush the bytes to instead of growing
* the array.
*/
private Writer writer;
private static final char[] CA =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
.toCharArray();
/**
* Creates a new byte array output stream, with a buffer capacity of
* the specified size, in bytes.
*
* @param size the initial size.
* @param writer the writer we'll flush to once
* we reach our capacity
*
* @throws IllegalArgumentException if size is negative.
*/
public Base64OutputStreamWriter(int size, Writer writer) {
if (size < 0) {
throw new IllegalArgumentException("Negative initial size: "
+ size);
}
buf = new byte[size];
chars = new char[size];
totalCharsWritten = 0;
this.writer = writer;
}
/**
* Writes the specified byte to this byte array output stream.
*
* @param b the byte to be written.
*/
public void write(int b) throws IOException {
throw new UnsupportedOperationException();
}
/**
* Writes len bytes from the specified byte array
* starting at offset off to this byte array output stream.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
*/
@Override
public void write(byte b[], int off, int len) throws IOException {
if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
if ((count + len) > buf.length) {
encodePendingBytes(false);
}
System.arraycopy(b, off, buf, count, len);
count += len;
}
/**
* Calls through to {@link #write(byte[], int, int)}/
* @param b the bytes to write
* @throws IOException if an error occurs
*/
@Override
public void write(byte b[]) throws IOException {
write(b, 0, b.length);
}
/** Closing Base64OutputStreamWriter does nothing. */
@Override
public void close() throws IOException {
}
/**
* Encodes the remaining bytes and flushes the char[]
* to the wrapped Writer.
*
* @throws IOException if an error occurs writing the remaining bytes
*/
public void finish() throws IOException {
encodePendingBytes(true);
}
/**
* @return the total number of characters written
*/
public int getTotalCharsWritten() {
return totalCharsWritten;
}
/**
* Base64 encode any bytes found in buf and
* store the result as characters in chars. This method
* will automatically write the contents of chars when
* necessary.
* @param pad flag to signal we're finalizing the encoding processes.
* @throws IOException if an error occurs
*/
private void encodePendingBytes(boolean pad) throws IOException {
int eLen = (count / 3) * 3; // Length of even 24-bits.
for (int s = 0; s < eLen;) {
// Copy next three bytes into lower 24 bits of int, paying attension to sign.
int i = (buf[s++] & 0xff) << 16
| (buf[s++] & 0xff) << 8
| (buf[s++] & 0xff);
if ((encCount + 4) > chars.length) {
// we're full, so write the encoded chars
// and reset the pointer
drainCharBuffer();
}
// Encode the int into four chars
chars[encCount++] = CA[(i >>> 18) & 0x3f];
chars[encCount++] = CA[(i >>> 12) & 0x3f];
chars[encCount++] = CA[(i >>> 6) & 0x3f];
chars[encCount++] = CA[i & 0x3f];
}
int left = (count - eLen);
if (!pad) {
// push the non-encoded bytes to the beginning of the byte array
// and set count to the end of those bytes
System.arraycopy(buf, eLen, buf, 0, left);
count = left;
} else {
drainCharBuffer();
// pad if necessary
if (left > 0) {
// Prepare the int
int i = ((buf[eLen] & 0xff) << 10) | (left == 2
? ((buf[count - 1]
& 0xff) << 2)
: 0);
// write last four chars
writer.write(CA[i >> 12]);
writer.write(CA[(i >>> 6) & 0x3f]);
writer.write(left == 2 ? CA[i & 0x3f] : '=');
writer.write('=');
}
}
}
/**
*
Write the contents of chars to the
* wrapped Writer and reset encCount
* to zero.
* @throws IOException if an error occurs
*/
private void drainCharBuffer() throws IOException {
writer.write(chars, 0, encCount);
totalCharsWritten += encCount;
encCount = 0;
}
// Test Case: com.sun.faces.io.TestIO
} // END Base64OutputStreamWriter