📄 d0981a3d6d36001b19ca9d8cdf62cf01
字号:
this.encode = encode;
this.bufferLength = encode ? 4 : 3;
this.buffer = new byte[ bufferLength ];
this.position = -1;
this.lineLength = 0;
} // end constructor
/**
* Reads enough of the input stream to convert
* to/from Base64 and returns the next byte.
*
* @return next byte
* @since 1.3
*/
public int read() throws java.io.IOException
{
// Do we need to get data?
if( position < 0 )
{
if( encode )
{
byte[] b3 = new byte[3];
int numBinaryBytes = 0;
for( int i = 0; i < 3; i++ )
{
try
{
int b = in.read();
// If end of stream, b is -1.
if( b >= 0 )
{
b3[i] = (byte)b;
numBinaryBytes++;
} // end if: not end of stream
} // end try: read
catch( java.io.IOException e )
{
// Only a problem if we got no data at all.
if( i == 0 )
throw e;
} // end catch
} // end for: each needed input byte
if( numBinaryBytes > 0 )
{
encode3to4( b3, 0, numBinaryBytes, buffer, 0 );
position = 0;
numSigBytes = 4;
} // end if: got data
else
{
return -1;
} // end else
} // end if: encoding
// Else decoding
else
{
byte[] b4 = new byte[4];
int i = 0;
for( i = 0; i < 4; i++ )
{
// Read four "meaningful" bytes:
int b = 0;
do{ b = in.read(); }
while( b >= 0 && DECODABET[ b & 0x7f ] <= WHITE_SPACE_ENC );
if( b < 0 )
break; // Reads a -1 if end of stream
b4[i] = (byte)b;
} // end for: each needed input byte
if( i == 4 )
{
numSigBytes = decode4to3( b4, 0, buffer, 0 );
position = 0;
} // end if: got four characters
else if( i == 0 ){
return -1;
} // end else if: also padded correctly
else
{
// Must have broken out from above.
throw new java.io.IOException( "Improperly padded Base64 input." );
} // end
} // end else: decode
} // end else: get data
// Got data?
if( position >= 0 )
{
// End of relevant data?
if( /*!encode &&*/ position >= numSigBytes )
return -1;
if( encode && breakLines && lineLength >= MAX_LINE_LENGTH )
{
lineLength = 0;
return '\n';
} // end if
else
{
lineLength++; // This isn't important when decoding
// but throwing an extra "if" seems
// just as wasteful.
int b = buffer[ position++ ];
if( position >= bufferLength )
position = -1;
return b & 0xFF; // This is how you "cast" a byte that's
// intended to be unsigned.
} // end else
} // end if: position >= 0
// Else error
else
{
// When JDK1.4 is more accepted, use an assertion here.
throw new java.io.IOException( "Error in Base64 code reading stream." );
} // end else
} // end read
/**
* Calls {@link #read} repeatedly until the end of stream
* is reached or <var>len</var> bytes are read.
* Returns number of bytes read into array or -1 if
* end of stream is encountered.
*
* @param dest array to hold values
* @param off offset for array
* @param len max number of bytes to read into array
* @return bytes read into array or -1 if end of stream is encountered.
* @since 1.3
*/
public int read( byte[] dest, int off, int len ) throws java.io.IOException
{
int i;
int b;
for( i = 0; i < len; i++ )
{
b = read();
//if( b < 0 && i == 0 )
// return -1;
if( b >= 0 )
dest[off + i] = (byte)b;
else if( i == 0 )
return -1;
else
break; // Out of 'for' loop
} // end for: each byte read
return i;
} // end read
} // end inner class InputStream
/* ******** I N N E R C L A S S O U T P U T S T R E A M ******** */
/**
* A {@link Base64#OutputStream} will write data to another
* {@link java.io.OutputStream}, given in the constructor,
* and encode/decode to/from Base64 notation on the fly.
*
* @see Base64
* @see java.io.FilterOutputStream
* @since 1.3
*/
public static class OutputStream extends java.io.FilterOutputStream
{
private boolean encode;
private int position;
private byte[] buffer;
private int bufferLength;
private int lineLength;
private boolean breakLines;
/**
* Constructs a {@link Base64#OutputStream} in ENCODE mode.
*
* @param out the {@link java.io.OutputStream} to which data will be written.
* @since 1.3
*/
public OutputStream( java.io.OutputStream out )
{
this( out, Base64.ENCODE );
} // end constructor
/**
* Constructs a {@link Base64#OutputStream} in
* either ENCODE or DECODE mode.
*
* @param out the {@link java.io.OutputStream} to which data will be written.
* @param encode Conversion direction
* @see Base64#ENCODE
* @see Base64#DECODE
* @since 1.3
*/
public OutputStream( java.io.OutputStream out, boolean encode )
{
this( out, encode, true );
} // end constructor
/**
* 根据解码或编码，构建输出流类；（OutputStream）
*/
public OutputStream( java.io.OutputStream out, boolean encode, boolean breakLines )
{
super( out );
this.breakLines = breakLines;
this.encode = encode;
this.bufferLength = encode ? 3 : 4;
this.buffer = new byte[ bufferLength ];
this.position = 0;
this.lineLength = 0;
} // end constructor
/**
* 对base64进行解码或编码时，将字节输出。
* 编码时，一次缓冲3个字节；解码时，一次缓冲四个字节；
*/
public void write(int theByte) throws java.io.IOException
{
if( encode )
{
buffer[ position++ ] = (byte)theByte;
if( position >= bufferLength ) // Enough to encode.
{
out.write( Base64.encode3to4( buffer, bufferLength ) );
lineLength += 4;
if( breakLines && lineLength >= MAX_LINE_LENGTH )
{
out.write( NEW_LINE );
lineLength = 0;
} // end if: end of line
position = 0;
} // end if: enough to output
} // end if: encoding
// Else, Decoding
else
{
// Meaningful Base64 character?
if( DECODABET[ theByte & 0x7f ] > WHITE_SPACE_ENC )
{
buffer[ position++ ] = (byte)theByte;
if( position >= bufferLength ) // Enough to output.
{
out.write( Base64.decode4to3( buffer ) );
position = 0;
} // end if: enough to output
} // end if: meaningful base64 character
else if( DECODABET[ theByte & 0x7f ] != WHITE_SPACE_ENC )
{
throw new java.io.IOException( "Invalid character in Base64 data." );
} // end else: not white space either
} // end else: decoding
} // end write
/**
* 重复调用函数直至调用len次
*/
public void write( byte[] theBytes, int off, int len ) throws java.io.IOException
{
for( int i = 0; i < len; i++ )
{
write( theBytes[ off + i ] );
} // end for: each byte written
} // end write
/**
* 编码时对base64进行补位，如果出错就抛出异常；
*/
public void flush() throws java.io.IOException
{
super.flush();
if( position > 0 )
{
if( encode )
{
out.write( Base64.encode3to4( buffer, position ) );
position = 0;
} // end if: encoding
else
{
throw new java.io.IOException( "Base64 input not properly padded." );
} // end else: decoding
} // end if: buffer partially full
out.flush();
} // end flush
/**
* 刷新和关闭流
*/
public void close() throws java.io.IOException
{
super.close();
//this.flush();
out.close();
buffer = null;
out = null;
} // end close
} // end inner class OutputStream
} // end class Base64
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -