net.hasor.utils.io.output.Base64OutputStream Maven / Gradle / Ivy
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/*
* Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
* All rights reserved.
*/
package net.hasor.utils.io.output;
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 Base64OutputStream 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 Base64OutputStream(final int size, final Writer writer) {
if (size < 0) {
throw new IllegalArgumentException("Negative initial size: " + size);
}
this.buf = new byte[size];
this.chars = new char[size];
this.totalCharsWritten = 0;
this.writer = writer;
}
/**
* Writes the specified byte to this byte array output stream.
*
* @param b the byte to be written.
*/
@Override
public void write(final 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(final byte b[], final int off, final 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 (this.count + len > this.buf.length) {
this.encodePendingBytes(false);
}
System.arraycopy(b, off, this.buf, this.count, len);
this.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(final byte b[]) throws IOException {
this.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 {
this.encodePendingBytes(true);
}
/**
* @return the total number of characters written
*/
public int getTotalCharsWritten() {
return this.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(final boolean pad) throws IOException {
int eLen = this.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 = (this.buf[s++] & 0xff) << 16 | (this.buf[s++] & 0xff) << 8 | this.buf[s++] & 0xff;
if (this.encCount + 4 > this.chars.length) {
// we're full, so write the encoded chars
// and reset the pointer
this.drainCharBuffer();
}
// Encode the int into four chars
this.chars[this.encCount++] = Base64OutputStream.CA[i >>> 18 & 0x3f];
this.chars[this.encCount++] = Base64OutputStream.CA[i >>> 12 & 0x3f];
this.chars[this.encCount++] = Base64OutputStream.CA[i >>> 6 & 0x3f];
this.chars[this.encCount++] = Base64OutputStream.CA[i & 0x3f];
}
int left = this.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(this.buf, eLen, this.buf, 0, left);
this.count = left;
} else {
this.drainCharBuffer();
// pad if necessary
if (left > 0) {
// Prepare the int
int i = (this.buf[eLen] & 0xff) << 10 | (left == 2 ? (this.buf[this.count - 1] & 0xff) << 2 : 0);
// write last four chars
this.writer.write(Base64OutputStream.CA[i >> 12]);
this.writer.write(Base64OutputStream.CA[i >>> 6 & 0x3f]);
this.writer.write(left == 2 ? Base64OutputStream.CA[i & 0x3f] : '=');
this.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 {
this.writer.write(this.chars, 0, this.encCount);
this.totalCharsWritten += this.encCount;
this.encCount = 0;
}
// Test Case: com.sun.faces.io.TestIO
} // END Base64OutputStreamWriter