Java tutorial
/* * * The DbUnit Database Testing Framework * Copyright (C)2002-2004, DbUnit.org * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ import java.io.FileInputStream; /** * <p> * I am placing this code in the Public Domain. Do with it as you will. * This software comes with no guarantees or warranties but with * plenty of well-wishing instead! * Please visit <a href="http://iharder.net/base64">http://iharder.net/base64</a> * periodically to check for updates or to contribute improvements. * </p> * * @author Robert Harder (rharder@usa.net) * @author Last changed by: $Author: gommma $ * @version $Revision: 769 $ $Date: 2008-08-02 09:31:15 +0200 (sab, 02 ago 2008) $ * @since 1.3 */ public class Base64 { /** Specify encoding (value is <tt>true</tt>). */ public final static boolean ENCODE = true; /** Specify decoding (value is <tt>false</tt>). */ public final static boolean DECODE = false; /** Maximum line length (76) of Base64 output. */ private final static int MAX_LINE_LENGTH = 76; /** The equals sign (=) as a byte. */ private final static byte EQUALS_SIGN = (byte) '='; /** The new line character (\n) as a byte. */ private final static byte NEW_LINE = (byte) '\n'; /** The 64 valid Base64 values. */ private final static byte[] ALPHABET = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) '+', (byte) '/' }; /** * Translates a Base64 value to either its 6-bit reconstruction value * or a negative number indicating some other meaning. **/ private final static byte[] DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8 -5, -5, // Whitespace: Tab and Linefeed -9, -9, // Decimal 11 - 12 -5, // Whitespace: Carriage Return -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26 -9, -9, -9, -9, -9, // Decimal 27 - 31 -5, // Whitespace: Space -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42 62, // Plus sign at decimal 43 -9, -9, -9, // Decimal 44 - 46 63, // Slash at decimal 47 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine -9, -9, -9, // Decimal 58 - 60 -1, // Equals sign at decimal 61 -9, -9, -9, // Decimal 62 - 64 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N' 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z' -9, -9, -9, -9, -9, -9, // Decimal 91 - 96 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm' 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z' -9, -9, -9, -9 // Decimal 123 - 126 /*,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 - 152 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 179 - 191 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 - 230 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255 */ }; private final static byte BAD_ENCODING = -9; // Indicates error in encoding private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding /** Defeats instantiation. */ private Base64() { } /** Testing. */ public static void main(String[] args) { String s = "Hello, world"; s = "abcd"; //s = System.getProperties().toString(); //System.out.println( s + ": \n [" + encode( s ) + "]\n [" + decode(encode(s)) + "]" ); byte[] b = encodeString(s).getBytes(); byte[] c = decode(b, 0, b.length); System.out.println("\n\n" + s + ":" + new String(b) + ":" + new String(c)); try { FileInputStream fis = new FileInputStream("c:\\abcd.txt"); InputStream b64is = new InputStream(fis, DECODE); int ib = 0; while ((ib = b64is.read()) > 0) { //System.out.print( new String( ""+(char)ib ) ); } } // end try catch (Exception e) { e.printStackTrace(); } } /* ******** E N C O D I N G M E T H O D S ******** */ /** * Encodes the first three bytes of array <var>threeBytes</var> * and returns a four-byte array in Base64 notation. * * @param threeBytes the array to convert * @return four byte array in Base64 notation. * @since 1.3 */ private static byte[] encode3to4(byte[] threeBytes) { return encode3to4(threeBytes, 3); } // end encodeToBytes /** * Encodes up to the first three bytes of array <var>threeBytes</var> * and returns a four-byte array in Base64 notation. * The actual number of significant bytes in your array is * given by <var>numSigBytes</var>. * The array <var>threeBytes</var> needs only be as big as * <var>numSigBytes</var>. * * @param threeBytes the array to convert * @param numSigBytes the number of significant bytes in your array * @return four byte array in Base64 notation. * @since 1.3 */ private static byte[] encode3to4(byte[] threeBytes, int numSigBytes) { byte[] dest = new byte[4]; encode3to4(threeBytes, 0, numSigBytes, dest, 0); return dest; } /** * Encodes up to three bytes of the array <var>source</var> * and writes the resulting four Base64 bytes to <var>destination</var>. * The source and destination arrays can be manipulated * anywhere along their length by specifying * <var>srcOffset</var> and <var>destOffset</var>. * This method does not check to make sure your arrays * are large enough to accomodate <var>srcOffset</var> + 3 for * the <var>source</var> array or <var>destOffset</var> + 4 for * the <var>destination</var> array. * The actual number of significant bytes in your array is * given by <var>numSigBytes</var>. * * @param source the array to convert * @param srcOffset the index where conversion begins * @param numSigBytes the number of significant bytes in your array * @param destination the array to hold the conversion * @param destOffset the index where output will be put * @return the <var>destination</var> array * @since 1.3 */ private static byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset) { // 1 2 3 // 01234567890123456789012345678901 Bit position // --------000000001111111122222222 Array position from threeBytes // --------| || || || | Six bit groups to index ALPHABET // >>18 >>12 >> 6 >> 0 Right shift necessary // 0x3f 0x3f 0x3f Additional AND // Create buffer with zero-padding if there are only one or two // significant bytes passed in the array. // We have to shift left 24 in order to flush out the 1's that appear // when Java treats a value as negative that is cast from a byte to an int. int inBuff = (numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0) | (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0) | (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0); switch (numSigBytes) { case 3: destination[destOffset] = ALPHABET[(inBuff >>> 18)]; destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f]; destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f]; destination[destOffset + 3] = ALPHABET[(inBuff) & 0x3f]; return destination; case 2: destination[destOffset] = ALPHABET[(inBuff >>> 18)]; destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f]; destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f]; destination[destOffset + 3] = EQUALS_SIGN; return destination; case 1: destination[destOffset] = ALPHABET[(inBuff >>> 18)]; destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f]; destination[destOffset + 2] = EQUALS_SIGN; destination[destOffset + 3] = EQUALS_SIGN; return destination; default: return destination; } // end switch } // end encode3to4 /** * Serializes an object and returns the Base64-encoded * version of that serialized object. If the object * cannot be serialized or there is another error, * the method will return <tt>null</tt>. * * @param serializableObject The object to encode * @return The Base64-encoded object * @since 1.4 */ public static String encodeObject(java.io.Serializable serializableObject) { java.io.ByteArrayOutputStream baos = null; java.io.OutputStream b64os = null; java.io.ObjectOutputStream oos = null; try { baos = new java.io.ByteArrayOutputStream(); b64os = new OutputStream(baos, Base64.ENCODE); oos = new java.io.ObjectOutputStream(b64os); oos.writeObject(serializableObject); } // end try catch (java.io.IOException e) { e.printStackTrace(); return null; } // end catch finally { try { oos.close(); b64os.close(); baos.close(); } catch (Exception e) { } } // end finally return new String(baos.toByteArray()); } // end encode /** * Encodes a byte array into Base64 notation. * Equivalen to calling * <code>encodeBytes( source, 0, source.length )</code> * * @param source The data to convert * @since 1.4 */ public static String encodeBytes(byte[] source) { return encodeBytes(source, 0, source.length); } // end encodeBytes /** * Encodes a byte array into Base64 notation. * * @param source The data to convert * @param off Offset in array where conversion should begin * @param len Length of data to convert * @since 1.4 */ public static String encodeBytes(byte[] source, int off, int len) { int len43 = len * 4 / 3; byte[] outBuff = new byte[(len43) // Main 4:3 + ((len % 3) > 0 ? 4 : 0) // Account for padding + (len43 / MAX_LINE_LENGTH)]; // New lines int d = 0; int e = 0; int len2 = len - 2; int lineLength = 0; for (; d < len2; d += 3, e += 4) { encode3to4(source, d, 3, outBuff, e); lineLength += 4; if (lineLength == MAX_LINE_LENGTH) { outBuff[e + 4] = NEW_LINE; e++; lineLength = 0; } // end if: end of line } // en dfor: each piece of array if (d < len) { encode3to4(source, d, len - d, outBuff, e); e += 4; } // end if: some padding needed return new String(outBuff, 0, e); } // end encodeBytes /** * Encodes a string in Base64 notation with line breaks * after every 75 Base64 characters. * * @param s the string to encode * @return the encoded string * @since 1.3 */ public static String encodeString(String s) { return encodeBytes(s.getBytes()); } // end encodeString /* ******** D E C O D I N G M E T H O D S ******** */ /** * Decodes the first four bytes of array <var>fourBytes</var> * and returns an array up to three bytes long with the * decoded values. * * @param fourBytes the array with Base64 content * @return array with decoded values * @since 1.3 */ private static byte[] decode4to3(byte[] fourBytes) { byte[] outBuff1 = new byte[3]; int count = decode4to3(fourBytes, 0, outBuff1, 0); byte[] outBuff2 = new byte[count]; for (int i = 0; i < count; i++) outBuff2[i] = outBuff1[i]; return outBuff2; } /** * Decodes four bytes from array <var>source</var> * and writes the resulting bytes (up to three of them) * to <var>destination</var>. * The source and destination arrays can be manipulated * anywhere along their length by specifying * <var>srcOffset</var> and <var>destOffset</var>. * This method does not check to make sure your arrays * are large enough to accomodate <var>srcOffset</var> + 4 for * the <var>source</var> array or <var>destOffset</var> + 3 for * the <var>destination</var> array. * This method returns the actual number of bytes that * were converted from the Base64 encoding. * * * @param source the array to convert * @param srcOffset the index where conversion begins * @param destination the array to hold the conversion * @param destOffset the index where output will be put * @return the number of decoded bytes converted * @since 1.3 */ private static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset) { // Example: Dk== if (source[srcOffset + 2] == EQUALS_SIGN) { int outBuff = ((DECODABET[source[srcOffset]] << 24) >>> 6) | ((DECODABET[source[srcOffset + 1]] << 24) >>> 12); destination[destOffset] = (byte) (outBuff >>> 16); return 1; } // Example: DkL= else if (source[srcOffset + 3] == EQUALS_SIGN) { int outBuff = ((DECODABET[source[srcOffset]] << 24) >>> 6) | ((DECODABET[source[srcOffset + 1]] << 24) >>> 12) | ((DECODABET[source[srcOffset + 2]] << 24) >>> 18); destination[destOffset] = (byte) (outBuff >>> 16); destination[destOffset + 1] = (byte) (outBuff >>> 8); return 2; } // Example: DkLE else { int outBuff = ((DECODABET[source[srcOffset]] << 24) >>> 6) | ((DECODABET[source[srcOffset + 1]] << 24) >>> 12) | ((DECODABET[source[srcOffset + 2]] << 24) >>> 18) | ((DECODABET[source[srcOffset + 3]] << 24) >>> 24); destination[destOffset] = (byte) (outBuff >> 16); destination[destOffset + 1] = (byte) (outBuff >> 8); destination[destOffset + 2] = (byte) (outBuff); return 3; } } // end decodeToBytes /** * Decodes data from Base64 notation. * * @param s the string to decode * @return the decoded data * @since 1.4 */ public static byte[] decode(String s) { byte[] bytes = s.getBytes(); return decode(bytes, 0, bytes.length); } // end decode /** * Decodes data from Base64 notation and * returns it as a string. * Equivalent to calling * <code>new String( decode( s ) )</code> * * @param s the string to decode * @return The data as a string * @since 1.4 */ public static String decodeToString(String s) { return new String(decode(s)); } // end decodeToString /** * Attempts to decode Base64 data and deserialize a Java * Object within. Returns <tt>null</tt> if there was an error. * * @param encodedObject The Base64 data to decode * @return The decoded and deserialized object * @since 1.4 */ public static Object decodeToObject(String encodedObject) { byte[] objBytes = decode(encodedObject); java.io.ByteArrayInputStream bais = null; java.io.ObjectInputStream ois = null; try { bais = new java.io.ByteArrayInputStream(objBytes); ois = new java.io.ObjectInputStream(bais); return ois.readObject(); } // end try catch (java.io.IOException e) { e.printStackTrace(); return null; } // end catch catch (ClassNotFoundException e) { e.printStackTrace(); return null; } // end catch finally { try { bais.close(); ois.close(); } catch (Exception e) { } } // end finally } // end decodeObject /** * Decodes Base64 content in byte array format and returns * the decoded byte array. * * @param source The Base64 encoded data * @param off The offset of where to begin decoding * @param len The length of characters to decode * @return decoded data * @since 1.3 */ public static byte[] decode(byte[] source, int off, int len) { int len34 = len * 3 / 4; byte[] outBuff = new byte[len34]; // Upper limit on size of output int outBuffPosn = 0; byte[] b4 = new byte[4]; int b4Posn = 0; int i = 0; byte sbiCrop = 0; byte sbiDecode = 0; for (i = 0; i < len; i++) { sbiCrop = (byte) (source[i] & 0x7f); // Only the low seven bits sbiDecode = DECODABET[sbiCrop]; if (sbiDecode >= WHITE_SPACE_ENC) // White space, Equals sign or better { if (sbiDecode >= EQUALS_SIGN_ENC) { b4[b4Posn++] = sbiCrop; if (b4Posn > 3) { outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn); b4Posn = 0; // If that was the equals sign, break out of 'for' loop if (sbiCrop == EQUALS_SIGN) break; } // end if: quartet built } // end if: equals sign or better } // end if: white space, equals sign or better else { System.err.println("Bad Base64 input character at " + i + ": " + source[i] + "(decimal)"); return null; } // end else: } // each input character byte[] out = new byte[outBuffPosn]; System.arraycopy(outBuff, 0, out, 0, outBuffPosn); return out; } // end decode /* ******** I N N E R C L A S S I N P U T S T R E A M ******** */ /** * A {@link Base64.InputStream} will read data from another * {@link java.io.InputStream}, given in the constructor, * and encode/decode to/from Base64 notation on the fly. * * @see Base64 * @see java.io.FilterInputStream * @since 1.3 */ public static class InputStream extends java.io.FilterInputStream { private boolean encode; // Encoding or decoding private int position; // Current position in the buffer private byte[] buffer; // Small buffer holding converted data private int bufferLength; // Length of buffer (3 or 4) private int numSigBytes; // Number of meaningful bytes in the buffer /** * Constructs a {@link Base64.InputStream} in DECODE mode. * * @param in the {@link java.io.InputStream} from which to read data. * @since 1.3 */ public InputStream(java.io.InputStream in) { this(in, Base64.DECODE); } // end constructor /** * Constructs a {@link Base64.InputStream} in * either ENCODE or DECODE mode. * * @param in the {@link java.io.InputStream} from which to read data. * @param encode Conversion direction * @see Base64#ENCODE * @see Base64#DECODE * @since 1.3 */ public InputStream(java.io.InputStream in, boolean encode) { super(in); this.encode = encode; this.bufferLength = encode ? 4 : 3; this.buffer = new byte[bufferLength]; this.position = -1; } // 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]; numSigBytes = 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; numSigBytes++; } // 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 (numSigBytes > 0) { encode3to4(b3, 0, numSigBytes, buffer, 0); position = 0; } // end if: got data } // end if: encoding // Else decoding else { byte[] b4 = new byte[4]; int i = 0; for (i = 0; i < 4; i++) { 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 } // end else: decode } // end else: get data // Got data? if (position >= 0) { // End of relevant data? if (position >= numSigBytes) return -1; int b = buffer[position++]; if (position >= bufferLength) position = -1; return b; } // end if: position >= 0 // Else error else return -1; } // 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) return -1; dest[off + i] = (byte) b; } // 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; /** * 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) { super(out); this.encode = encode; this.bufferLength = encode ? 3 : 4; this.buffer = new byte[bufferLength]; this.position = 0; this.lineLength = 0; } // end constructor /** * Writes the byte to the output stream after * converting to/from Base64 notation. * When encoding, bytes are buffered three * at a time before the output stream actually * gets a write() call. * When decoding, bytes are buffered four * at a time. * * @param theByte the byte to write * @since 1.3 */ public void write(int theByte) throws java.io.IOException { buffer[position++] = (byte) theByte; if (position >= bufferLength) { if (encode) { out.write(Base64.encode3to4(buffer, bufferLength)); lineLength += 4; if (lineLength >= MAX_LINE_LENGTH) { out.write(NEW_LINE); lineLength = 0; } // end if: end o fline } // end if: encoding else out.write(Base64.decode4to3(buffer)); position = 0; } // end if: convert and flush } // end write /** * Calls {@link #write} repeatedly until <var>len</var> * bytes are written. * * @param theBytes array from which to read bytes * @param off offset for array * @param len max number of bytes to read into array * @since 1.3 */ 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 /** * Appropriately pads Base64 notation when encoding * or throws an exception if Base64 input is not * properly padded when decoding. * * @since 1.3 */ public void flush() throws java.io.IOException { if (position > 0) { if (encode) { out.write(Base64.encode3to4(buffer, position)); } // end if: encoding else { throw new java.io.IOException("Base64 input not properly padded."); } // end else: decoding } // end if: buffer partially full super.flush(); out.flush(); } // end flush /** * Flushes and closes stream. * * @since 1.3 */ public void close() throws java.io.IOException { this.flush(); super.close(); out.close(); buffer = null; out = null; } // end close } // end inner class OutputStream } // end class Base64