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CompressionOutputStream.javaAPI DocExample4652Wed Apr 19 11:20:14 BST 2000examples.rmisocfac

CompressionOutputStream

public class CompressionOutputStream extends FilterOutputStream implements CompressionConstants

Fields Summary
int[]
buf
int
bufPos
Constructors Summary
public CompressionOutputStream(OutputStream out)

        super(out);
Methods Summary
public voidflush()

    while (bufPos > 0)
      writeCode(NOP);
public voidwrite(int b)

 

    /*  
     * This method writes one byte to the socket stream. 
     */ 
          
        // force argument to one byte
        b &= 0xFF;  

        // Look up pos in codeTable to get its encoding. 
        int pos = codeTable.indexOf((char)b);

        if (pos != -1){
            // If pos is in the codeTable, write BASE + pos into buf. 
            // By adding BASE to pos, we know that the characters in
            // the codeTable will always have a code between 2 and 63
            // inclusive. This allows us to use RAW (RAW is equal to
            // 1) to signify that the next two groups of 6-bits are 
            // necessary for decompression of the next character.
	    
            writeCode(BASE + pos);
        } else {
            // Otherwise, write RAW into buf to signify that the
            // Character is being sent in 12 bits.
            writeCode(RAW);

            // Write the last 4 bits of b into the buf.
            writeCode(b >> 4);

            // Truncate b to contain data in only the first 4 bits, 
            // and write the first 4 bits of b into buf.
            writeCode(b & 0xF);
        }
public voidwrite(byte[] b, int off, int len)

        /*
         * This implementation is quite inefficient because it has to
         * call the other write method for every byte in the array.  It
         * could be optimized for performance by doing all the processing
         * in this method.
         */
        for (int i = 0; i < len; i++)
            write(b[off + i]);
private voidwriteCode(int c)

        buf[bufPos++] = c;
        if (bufPos == 5) {      // write next word when we have 5 codes
            int pack = (buf[0] << 24) | (buf[1] << 18) | (buf[2] << 12) |
                       (buf[3] << 6) | buf[4];
            out.write((pack >>> 24) & 0xFF);
            out.write((pack >>> 16) & 0xFF);
            out.write((pack >>> 8)  & 0xFF);
            out.write((pack >>> 0)  & 0xFF);
            bufPos = 0;
        }