如果文件太大,就有点麻烦 如果不大,可以直接 new sun.misc.BASE64Encoder().encode(内容); 内容是byte[],返回是String
import java.io.*; // needed only for main() method. /** * Provides encoding of raw bytes to base64-encoded characters, and * decoding of base64 characters to raw bytes. * * @author Kevin Kelley ([email protected]) * @version 1.3 * @date 06 August 1998 * @modified 14 February 2000 * @modified 22 September 2000 */ public class Base64 {/** * returns an array of base64-encoded characters to represent the * passed data array. * * @param data the array of bytes to encode * @return base64-coded character array. */ static public char[] encode(byte[] data) { char[] out = new char[((data.length + 2) / 3) * 4]; // // 3 bytes encode to 4 chars. Output is always an even // multiple of 4 characters. // for (int i=0, index=0; i<data.length; i+=3, index+=4) { boolean quad = false; boolean trip = false; int val = (0xFF & (int) data[i]); val <<= 8; if ((i+1) < data.length) { val |= (0xFF & (int) data[i+1]); trip = true; } val <<= 8; if ((i+2) < data.length) { val |= (0xFF & (int) data[i+2]); quad = true; } out[index+3] = alphabet[(quad? (val & 0x3F): 64)]; val >>= 6; out[index+2] = alphabet[(trip? (val & 0x3F): 64)]; val >>= 6; out[index+1] = alphabet[val & 0x3F]; val >>= 6; out[index+0] = alphabet[val & 0x3F]; } return out; } /** * Decodes a BASE-64 encoded stream to recover the original * data. White space before and after will be trimmed away, * but no other manipulation of the input will be performed. * * As of version 1.2 this method will properly handle input * containing junk characters (newlines and the like) rather * than throwing an error. It does this by pre-parsing the * input and generating from that a count of VALID input * characters. **/ static public byte[] decode(char[] data) { // as our input could contain non-BASE64 data (newlines, // whitespace of any sort, whatever) we must first adjust // our count of USABLE data so that... // (a) we don't misallocate the output array, and // (b) think that we miscalculated our data length // just because of extraneous throw-away junk int tempLen = data.length; for( int ix=0; ix<data.length; ix++ ) { if( (data[ix] > 255) || codes[ data[ix] ] < 0 ) --tempLen; // ignore non-valid chars and padding } // calculate required length: // -- 3 bytes for every 4 valid base64 chars // -- plus 2 bytes if there are 3 extra base64 chars, // or plus 1 byte if there are 2 extra. int len = (tempLen / 4) * 3; if ((tempLen % 4) == 3) len += 2; if ((tempLen % 4) == 2) len += 1; byte[] out = new byte[len]; int shift = 0; // # of excess bits stored in accum int accum = 0; // excess bits int index = 0; // we now go through the entire array (NOT using the 'tempLen' value) for (int ix=0; ix<data.length; ix++) { int value = (data[ix]>255)? -1: codes[ data[ix] ]; if ( value >= 0 ) // skip over non-code { accum <<= 6; // bits shift up by 6 each time thru shift += 6; // loop, with new bits being put in accum |= value; // at the bottom. if ( shift >= 8 ) // whenever there are 8 or more shifted in, { shift -= 8; // write them out (from the top, leaving any out[index++] = // excess at the bottom for next iteration. (byte) ((accum >> shift) & 0xff); } } // we will also have skipped processing a padding null byte ('=') here; // these are used ONLY for padding to an even length and do not legally // occur as encoded data. for this reason we can ignore the fact that // no index++ operation occurs in that special case: the out[] array is // initialized to all-zero bytes to start with and that works to our // advantage in this combination. } // if there is STILL something wrong we just have to throw up now! if( index != out.length) { throw new Error("Miscalculated data length (wrote " + index + " instead of " + out.length + ")"); } return out; }/** added by Neal * * @param str String * @return String */public static String encodeString(String str){ byte[] bt = str.getBytes(); char[] cArray = Base64.encode(bt); return new String(cArray); }/** added by Neal * * @param str String * @return String */ public static String decodeString(String str){ char[] cArray = str.toCharArray(); byte[] bt = Base64.decode(cArray); return (new String(bt)); }// // code characters for values 0..63 // static private char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" .toCharArray();// // lookup table for converting base64 characters to value in range 0..63 // static private byte[] codes = new byte[256]; static { for (int i=0; i<256; i++) codes[i] = -1; for (int i = 'A'; i <= 'Z'; i++) codes[i] = (byte)( i - 'A'); for (int i = 'a'; i <= 'z'; i++) codes[i] = (byte)(26 + i - 'a'); for (int i = '0'; i <= '9'; i++) codes[i] = (byte)(52 + i - '0'); codes['+'] = 62; codes['/'] = 63; }
/////////////////////////////////////////////////// // remainder (main method and helper functions) is // for testing purposes only, feel free to clip it. ///////////////////////////////////////////////////public static void main(String[] args) { boolean decode = false; if (args.length == 0) { System.out.println("usage: java Base64 [-d[ecode]] filename"); System.exit(0); } for (int i=0; i<args.length; i++) { if ("-decode".equalsIgnoreCase(args[i])) decode = true; else if ("-d".equalsIgnoreCase(args[i])) decode = true; } String filename = args[args.length-1]; File file = new File(filename); if (!file.exists()) { System.out.println("Error: file '" + filename + "' doesn't exist!"); System.exit(0); } if (decode) { char[] encoded = readChars(file); byte[] decoded = decode(encoded); writeBytes(file, decoded); } else { byte[] decoded = readBytes(file); char[] encoded = encode(decoded); writeChars(file, encoded); } }private static byte[] readBytes(File file) { ByteArrayOutputStream baos = new ByteArrayOutputStream(); try { InputStream fis = new FileInputStream(file); InputStream is = new BufferedInputStream(fis); int count = 0; byte[] buf = new byte[16384]; while ((count=is.read(buf)) != -1) { if (count > 0) baos.write(buf, 0, count); } is.close(); } catch (Exception e) { e.printStackTrace(); } return baos.toByteArray(); }private static char[] readChars(File file) { CharArrayWriter caw = new CharArrayWriter(); try { Reader fr = new FileReader(file); Reader in = new BufferedReader(fr); int count = 0; char[] buf = new char[16384]; while ((count=in.read(buf)) != -1) { if (count > 0) caw.write(buf, 0, count); } in.close(); } catch (Exception e) { e.printStackTrace(); } return caw.toCharArray(); }private static void writeBytes(File file, byte[] data) { try { OutputStream fos = new FileOutputStream(file); OutputStream os = new BufferedOutputStream(fos); os.write(data); os.close(); } catch (Exception e) { e.printStackTrace(); } }private static void writeChars(File file, char[] data) { try { Writer fos = new FileWriter(file); Writer os = new BufferedWriter(fos); os.write(data); os.close(); } catch (Exception e) { e.printStackTrace(); } } /////////////////////////////////////////////////// // end of test code. ///////////////////////////////////////////////////}
如果不大,可以直接
new sun.misc.BASE64Encoder().encode(内容);
内容是byte[],返回是String
/**
* Provides encoding of raw bytes to base64-encoded characters, and
* decoding of base64 characters to raw bytes.
*
* @author Kevin Kelley ([email protected])
* @version 1.3
* @date 06 August 1998
* @modified 14 February 2000
* @modified 22 September 2000
*/
public class Base64 {/**
* returns an array of base64-encoded characters to represent the
* passed data array.
*
* @param data the array of bytes to encode
* @return base64-coded character array.
*/
static public char[] encode(byte[] data)
{
char[] out = new char[((data.length + 2) / 3) * 4]; //
// 3 bytes encode to 4 chars. Output is always an even
// multiple of 4 characters.
//
for (int i=0, index=0; i<data.length; i+=3, index+=4) {
boolean quad = false;
boolean trip = false; int val = (0xFF & (int) data[i]);
val <<= 8;
if ((i+1) < data.length) {
val |= (0xFF & (int) data[i+1]);
trip = true;
}
val <<= 8;
if ((i+2) < data.length) {
val |= (0xFF & (int) data[i+2]);
quad = true;
}
out[index+3] = alphabet[(quad? (val & 0x3F): 64)];
val >>= 6;
out[index+2] = alphabet[(trip? (val & 0x3F): 64)];
val >>= 6;
out[index+1] = alphabet[val & 0x3F];
val >>= 6;
out[index+0] = alphabet[val & 0x3F];
}
return out;
} /**
* Decodes a BASE-64 encoded stream to recover the original
* data. White space before and after will be trimmed away,
* but no other manipulation of the input will be performed.
*
* As of version 1.2 this method will properly handle input
* containing junk characters (newlines and the like) rather
* than throwing an error. It does this by pre-parsing the
* input and generating from that a count of VALID input
* characters.
**/
static public byte[] decode(char[] data)
{
// as our input could contain non-BASE64 data (newlines,
// whitespace of any sort, whatever) we must first adjust
// our count of USABLE data so that...
// (a) we don't misallocate the output array, and
// (b) think that we miscalculated our data length
// just because of extraneous throw-away junk int tempLen = data.length;
for( int ix=0; ix<data.length; ix++ )
{
if( (data[ix] > 255) || codes[ data[ix] ] < 0 )
--tempLen; // ignore non-valid chars and padding
}
// calculate required length:
// -- 3 bytes for every 4 valid base64 chars
// -- plus 2 bytes if there are 3 extra base64 chars,
// or plus 1 byte if there are 2 extra. int len = (tempLen / 4) * 3;
if ((tempLen % 4) == 3) len += 2;
if ((tempLen % 4) == 2) len += 1; byte[] out = new byte[len]; int shift = 0; // # of excess bits stored in accum
int accum = 0; // excess bits
int index = 0; // we now go through the entire array (NOT using the 'tempLen' value)
for (int ix=0; ix<data.length; ix++)
{
int value = (data[ix]>255)? -1: codes[ data[ix] ]; if ( value >= 0 ) // skip over non-code
{
accum <<= 6; // bits shift up by 6 each time thru
shift += 6; // loop, with new bits being put in
accum |= value; // at the bottom.
if ( shift >= 8 ) // whenever there are 8 or more shifted in,
{
shift -= 8; // write them out (from the top, leaving any
out[index++] = // excess at the bottom for next iteration.
(byte) ((accum >> shift) & 0xff);
}
}
// we will also have skipped processing a padding null byte ('=') here;
// these are used ONLY for padding to an even length and do not legally
// occur as encoded data. for this reason we can ignore the fact that
// no index++ operation occurs in that special case: the out[] array is
// initialized to all-zero bytes to start with and that works to our
// advantage in this combination.
} // if there is STILL something wrong we just have to throw up now!
if( index != out.length)
{
throw new Error("Miscalculated data length (wrote " + index + " instead of " + out.length + ")");
} return out;
}/** added by Neal
*
* @param str String
* @return String
*/public static String encodeString(String str){
byte[] bt = str.getBytes();
char[] cArray = Base64.encode(bt);
return new String(cArray);
}/** added by Neal
*
* @param str String
* @return String
*/
public static String decodeString(String str){
char[] cArray = str.toCharArray();
byte[] bt = Base64.decode(cArray);
return (new String(bt));
}//
// code characters for values 0..63
//
static private char[] alphabet =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
.toCharArray();//
// lookup table for converting base64 characters to value in range 0..63
//
static private byte[] codes = new byte[256];
static {
for (int i=0; i<256; i++) codes[i] = -1;
for (int i = 'A'; i <= 'Z'; i++) codes[i] = (byte)( i - 'A');
for (int i = 'a'; i <= 'z'; i++) codes[i] = (byte)(26 + i - 'a');
for (int i = '0'; i <= '9'; i++) codes[i] = (byte)(52 + i - '0');
codes['+'] = 62;
codes['/'] = 63;
}
// remainder (main method and helper functions) is
// for testing purposes only, feel free to clip it.
///////////////////////////////////////////////////public static void main(String[] args)
{
boolean decode = false; if (args.length == 0) {
System.out.println("usage: java Base64 [-d[ecode]] filename");
System.exit(0);
}
for (int i=0; i<args.length; i++) {
if ("-decode".equalsIgnoreCase(args[i])) decode = true;
else if ("-d".equalsIgnoreCase(args[i])) decode = true;
} String filename = args[args.length-1];
File file = new File(filename);
if (!file.exists()) {
System.out.println("Error: file '" + filename + "' doesn't exist!");
System.exit(0);
} if (decode)
{
char[] encoded = readChars(file);
byte[] decoded = decode(encoded);
writeBytes(file, decoded);
}
else
{
byte[] decoded = readBytes(file);
char[] encoded = encode(decoded);
writeChars(file, encoded);
}
}private static byte[] readBytes(File file)
{
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try
{
InputStream fis = new FileInputStream(file);
InputStream is = new BufferedInputStream(fis);
int count = 0;
byte[] buf = new byte[16384];
while ((count=is.read(buf)) != -1) {
if (count > 0) baos.write(buf, 0, count);
}
is.close();
}
catch (Exception e) { e.printStackTrace(); } return baos.toByteArray();
}private static char[] readChars(File file)
{
CharArrayWriter caw = new CharArrayWriter();
try
{
Reader fr = new FileReader(file);
Reader in = new BufferedReader(fr);
int count = 0;
char[] buf = new char[16384];
while ((count=in.read(buf)) != -1) {
if (count > 0) caw.write(buf, 0, count);
}
in.close();
}
catch (Exception e) { e.printStackTrace(); } return caw.toCharArray();
}private static void writeBytes(File file, byte[] data) {
try {
OutputStream fos = new FileOutputStream(file);
OutputStream os = new BufferedOutputStream(fos);
os.write(data);
os.close();
}
catch (Exception e) { e.printStackTrace(); }
}private static void writeChars(File file, char[] data) {
try {
Writer fos = new FileWriter(file);
Writer os = new BufferedWriter(fos);
os.write(data);
os.close();
}
catch (Exception e) { e.printStackTrace(); }
}
///////////////////////////////////////////////////
// end of test code.
///////////////////////////////////////////////////}