top.ibase4j.core.support.security

类 CharacterDecoder

java.lang.Object

top.ibase4j.core.support.security.CharacterDecoder

直接已知子类:

BASE64Decoder

public abstract class CharacterDecoder
extends Object

37 * This class defines the decoding half of character encoders. 38 * A character decoder is an algorithim for transforming 8 bit 39 * binary data that has been encoded into text by a character 40 * encoder, back into original binary form. 41 * 42 * The character encoders, in general, have been structured 43 * around a central theme that binary data can be encoded into 44 * text that has the form: 45 * 46 *

    47    *      [Buffer Prefix]
    48    *      [Line Prefix][encoded data atoms][Line Suffix]
    49    *      [Buffer Suffix]
    50    *
 

51 * 52 * Of course in the simplest encoding schemes, the buffer has no 53 * distinct prefix of suffix, however all have some fixed relationship 54 * between the text in an 'atom' and the binary data itself. 55 * 56 * In the CharacterEncoder and CharacterDecoder classes, one complete 57 * chunk of data is referred to as a buffer. Encoded buffers 58 * are all text, and decoded buffers (sometimes just referred to as 59 * buffers) are binary octets. 60 * 61 * To create a custom decoder, you must, at a minimum, overide three 62 * abstract methods in this class. 63 *

64 *

bytesPerAtom which tells the decoder how many bytes to 65 * expect from decodeAtom 66 *

decodeAtom which decodes the bytes sent to it as text. 67 *

bytesPerLine which tells the encoder the maximum number of 68 * bytes per line. 69 *

70 * 71 * In general, the character decoders return error in the form of a 72 * CEFormatException. The syntax of the detail string is 73 *

    74    *      DecoderClassName: Error message.
    75    *
 

76 * 77 * Several useful decoders have already been written and are 78 * referenced in the See Also list below. 79 * 80 * @author Chuck McManis 81 * @see CEFormatException 82 * @see CharacterEncoder 83 * @see UCDecoder 84 * @see UUDecoder 85 * @see BASE64Decoder 86

构造器概要

构造器

构造器和说明
CharacterDecoder()

方法概要

限定符和类型	方法和说明
protected abstract int	bytesPerAtom() Return the number of bytes per atom of decoding
protected abstract int	bytesPerLine() Return the maximum number of bytes that can be encoded per line
protected void	decodeAtom(PushbackInputStream aStream, OutputStream bStream, int l) 121 * This method does an actual decode.
byte[]	decodeBuffer(InputStream in) 199 * Decode the contents of the inputstream into a buffer. 200
void	decodeBuffer(InputStream aStream, OutputStream bStream) 145 * Decode the text from the InputStream and write the decoded 146 * octets to the OutputStream.
byte[]	decodeBuffer(String inputString) 182 * Alternate decode interface that takes a String containing the encoded 183 * buffer and returns a byte array containing the data. 184 * @exception CEFormatException An error has occured while decoding 185
protected void	decodeBufferPrefix(PushbackInputStream aStream, OutputStream bStream) decode the beginning of the buffer, by default this is a NOP.
protected void	decodeBufferSuffix(PushbackInputStream aStream, OutputStream bStream) decode the buffer suffix, again by default it is a NOP.
ByteBuffer	decodeBufferToByteBuffer(InputStream in) 216 * Decode the contents of the inputStream into a ByteBuffer. 217
ByteBuffer	decodeBufferToByteBuffer(String inputString) 208 * Decode the contents of the String into a ByteBuffer. 209
protected int	decodeLinePrefix(PushbackInputStream aStream, OutputStream bStream) 103 * This method should return, if it knows, the number of bytes 104 * that will be decoded.
protected void	decodeLineSuffix(PushbackInputStream aStream, OutputStream bStream) 113 * This method post processes the line, if there are error detection 114 * or correction codes in a line, they are generally processed by 115 * this method.
protected int	readFully(InputStream in, byte[] buffer, int offset, int len) 130 * This method works around the bizarre semantics of BufferedInputStream's 131 * read method. 132

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

CharacterDecoder

public CharacterDecoder()

方法详细资料

bytesPerAtom

protected abstract int bytesPerAtom()

Return the number of bytes per atom of decoding

bytesPerLine

protected abstract int bytesPerLine()

Return the maximum number of bytes that can be encoded per line

decodeBufferPrefix

protected void decodeBufferPrefix(PushbackInputStream aStream,
                                  OutputStream bStream)
                           throws IOException

decode the beginning of the buffer, by default this is a NOP.

抛出:

IOException

decodeBufferSuffix

protected void decodeBufferSuffix(PushbackInputStream aStream,
                                  OutputStream bStream)
                           throws IOException

decode the buffer suffix, again by default it is a NOP.

抛出:

IOException

decodeLinePrefix

protected int decodeLinePrefix(PushbackInputStream aStream,
                               OutputStream bStream)
                        throws IOException

103 * This method should return, if it knows, the number of bytes 104 * that will be decoded. Many formats such as uuencoding provide 105 * this information. By default we return the maximum bytes that 106 * could have been encoded on the line. 107

抛出:

IOException

decodeLineSuffix

protected void decodeLineSuffix(PushbackInputStream aStream,
                                OutputStream bStream)
                         throws IOException

113 * This method post processes the line, if there are error detection 114 * or correction codes in a line, they are generally processed by 115 * this method. The simplest version of this method looks for the 116 * (newline) character. 117

抛出:

IOException

decodeAtom

protected void decodeAtom(PushbackInputStream aStream,
                          OutputStream bStream,
                          int l)
                   throws IOException

121 * This method does an actual decode. It takes the decoded bytes and 122 * writes them to the OutputStream. The integer l tells the 123 * method how many bytes are required. This is always <= bytesPerAtom(). 124

抛出:

IOException

readFully

protected int readFully(InputStream in,
                        byte[] buffer,
                        int offset,
                        int len)
                 throws IOException

130 * This method works around the bizarre semantics of BufferedInputStream's 131 * read method. 132

抛出:

IOException

decodeBuffer

public void decodeBuffer(InputStream aStream,
                         OutputStream bStream)
                  throws IOException

145 * Decode the text from the InputStream and write the decoded 146 * octets to the OutputStream. This method runs until the stream 147 * is exhausted. 148 * @exception CEFormatException An error has occured while decoding 149 * @exception CEStreamExhausted The input stream is unexpectedly out of data 150

抛出:

IOException

decodeBuffer

public byte[] decodeBuffer(String inputString)
                    throws IOException

182 * Alternate decode interface that takes a String containing the encoded 183 * buffer and returns a byte array containing the data. 184 * @exception CEFormatException An error has occured while decoding 185

抛出:

IOException

decodeBuffer

public byte[] decodeBuffer(InputStream in)
                    throws IOException

199 * Decode the contents of the inputstream into a buffer. 200

抛出:

IOException

decodeBufferToByteBuffer

public ByteBuffer decodeBufferToByteBuffer(String inputString)
                                    throws IOException

208 * Decode the contents of the String into a ByteBuffer. 209

抛出:

IOException

decodeBufferToByteBuffer

public ByteBuffer decodeBufferToByteBuffer(InputStream in)
                                    throws IOException

216 * Decode the contents of the inputStream into a ByteBuffer. 217

抛出:

IOException