Base64 (stdlib 5.1.2 API)

java.lang.Object
- com.peterphi.std.util.Base64

```
public class Base64
extends Object
```
Encodes and decodes to and from Base64 notation.

Homepage: http://iharder.net/base64.

Example:

String encoded = Base64.encode( myByteArray );
byte[] myByteArray = Base64.decode( encoded );

The options parameter, which appears in a few places, is used to pass several pieces of information to the encoder. In the "higher level" methods such as encodeBytes( bytes, options ) the options parameter can be used to indicate such things as first gzipping the bytes before encoding them, not inserting linefeeds, and encoding using the URL-safe and Ordered dialects.

Note, according to RFC3548, Section 2.1, implementations should not add line feeds unless explicitly told to do so. I've got Base64 set the opposite way so that you tell it _not_ to add line feeds since I always thought line feeds were required -- I was wrong, but I'm reluctant to change the default behavior now. Sorry.

The constants defined in Base64 can be OR-ed together to combine options, so you might make a call like this:

String encoded = Base64.encodeBytes( mybytes, Base64.GZIP | Base64.DONT_BREAK_LINES );

to compress the data before encoding it and then making the output have no newline characters.

Change Log:
- v2.3.1 - Added encodeBytesToBytes(byte[], int, int, int) and some similar helper methods to be more efficient with memory by not returning a String but just a byte array.
- v2.3 - This is not a drop-in replacement! This is two years of comments and bug fixes queued up and finally executed. Thanks to everyone who sent me stuff, and I'm sorry I wasn't able to distribute your fixes to everyone else. Much bad coding was cleaned up including throwing exceptions where necessary instead of returning null values or something similar. Here are some changes that may affect you:
  - Does not break lines, by default. This is to keep in compliance with RFC3548.
  - Throws exceptions instead of returning null values. Because some operations (especially those that may permit the GZIP option) use IO streams, there is a possiblity of an java.io.IOException being thrown. After some discussion and thought, I've changed the behavior of the methods to throw java.io.IOExceptions rather than return null if ever there's an error. I think this is more appropriate, though it will require some changes to your code. Sorry, it should have been done this way to begin with.
  - Removed all references to System.out, System.err, and the like. Shame on me. All I can say is sorry they were ever there.
  - Throws NullPointerExceptions and IllegalArgumentExceptions as needed such as when passed arrays are null or offsets are invalid.
  - Cleaned up as much javadoc as I could to avoid any javadoc warnings. This was especially annoying before for people who were thorough in their own projects and then had gobs of javadoc warnings on this file.
- v2.2.1 - Fixed bug using URL_SAFE and ORDERED encodings. Fixed bug when using very small files (~< 40 bytes).
- v2.2 - Added some helper methods for encoding/decoding directly from one file to the next. Also added a main() method to support command line encoding/decoding from one file to the next. Also added these Base64 dialects:
  1. The default is RFC3548 format.
  2. Calling Base64.setFormat(Base64.BASE64_FORMAT.URLSAFE_FORMAT) generates URL and file name friendly format as described in Section 4 of RFC3548. http://www.faqs.org/rfcs/rfc3548.html
  3. Calling Base64.setFormat(Base64.BASE64_FORMAT.ORDERED_FORMAT) generates URL and file name friendly format that preserves lexical ordering as described in http://www.faqs.org/qa/rfcc-1940.html
  Special thanks to Jim Kellerman at http://www.powerset.com/ for contributing the new Base64 dialects.
- v2.1 - Cleaned up javadoc comments and unused variables and methods. Added some convenience methods for reading and writing to and from files.
- v2.0.2 - Now specifies UTF-8 encoding in places where the code fails on systems with other encodings (like EBCDIC).
- v2.0.1 - Fixed an error when decoding a single byte, that is, when the encoded data was a single byte.
- v2.0 - I got rid of methods that used booleans to set options. Now everything is more consolidated and cleaner. The code now detects when data that's being decoded is gzip-compressed and will decompress it automatically. Generally things are cleaner. You'll probably have to change some method calls that you were making to support the new options format (ints that you "OR" together).
- v1.5.1 - Fixed bug when decompressing and decoding to a byte[] using decode( String s, boolean gzipCompressed ). Added the ability to "suspend" encoding in the Output Stream so you can turn on and off the encoding if you need to embed base64 data in an otherwise "normal" stream (like an XML file).
- v1.5 - Output stream pases on flush() command but doesn't do anything itself. This helps when using GZIP streams. Added the ability to GZip-compress objects before encoding them.
- v1.4 - Added helper methods to read/write files.
- v1.3.6 - Fixed OutputStream.flush() so that 'position' is reset.
- v1.3.5 - Added flag to turn on and off line breaks. Fixed bug in input stream where last buffer being read, if not completely full, was not returned.
- v1.3.4 - Fixed when "improperly padded stream" error was thrown at the wrong time.
- v1.3.3 - Fixed I/O streams which were totally messed up.
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 http://iharder.net/base64 periodically to check for updates or to contribute improvements.
Version:

2.3.1

Author:

Robert Harder, rob@iharder.net

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DECODE` Specify decoding in first bit.
`static int`	`DO_BREAK_LINES` Do break lines when encoding.
`static int`	`ENCODE` Specify encoding in first bit.
`static int`	`GZIP` Specify that data should be gzip-compressed in second bit.
`static int`	`NO_OPTIONS` No options specified.
`static int`	`ORDERED` Encode using the special "ordered" dialect of Base64 described here: http://www.faqs.org/qa/rfcc-1940.html.
`static int`	`URL_SAFE` Encode using Base64-like encoding that is URL- and Filename-safe as described in Section 4 of RFC3548: http://www.faqs.org/rfcs/rfc3548.html.

Method Summary

Methods
Modifier and Type	Method and Description
`static byte[]`	`decode(byte[] source)` Low-level access to decoding ASCII characters in the form of a byte array.
`static byte[]`	`decode(byte[] source, int off, int len, int options)` Low-level access to decoding ASCII characters in the form of a byte array.
`static byte[]`	`decode(String s)` Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
`static byte[]`	`decode(String s, int options)` Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
`static void`	`decodeFileToFile(String infile, String outfile)` Reads `infile` and decodes it to `outfile`.
`static byte[]`	`decodeFromFile(String filename)` Convenience method for reading a base64-encoded file and decoding it.
`static void`	`decodeToFile(String dataToDecode, String filename)` Convenience method for decoding data to a file.
`static Object`	`decodeToObject(String encodedObject)` Attempts to decode Base64 data and deserialize a Java Object within.
`static void`	`encode(ByteBuffer raw, ByteBuffer encoded)` Performs Base64 encoding on the `raw` ByteBuffer, writing it to the `encoded` ByteBuffer.
`static void`	`encode(ByteBuffer raw, CharBuffer encoded)` Performs Base64 encoding on the `raw` ByteBuffer, writing it to the `encoded` CharBuffer.
`static String`	`encodeBytes(byte[] source)` Encodes a byte array into Base64 notation.
`static String`	`encodeBytes(byte[] source, int options)` Encodes a byte array into Base64 notation.
`static String`	`encodeBytes(byte[] source, int off, int len)` Encodes a byte array into Base64 notation.
`static String`	`encodeBytes(byte[] source, int off, int len, int options)` Encodes a byte array into Base64 notation.
`static byte[]`	`encodeBytesToBytes(byte[] source)` Similar to `encodeBytes(byte[])` but returns a byte array instead of instantiating a String.
`static byte[]`	`encodeBytesToBytes(byte[] source, int off, int len, int options)` Similar to `encodeBytes(byte[], int, int, int)` but returns a byte array instead of instantiating a String.
`static void`	`encodeFileToFile(String infile, String outfile)` Reads `infile` and encodes it to `outfile`.
`static String`	`encodeFromFile(String filename)` Convenience method for reading a binary file and base64-encoding it.
`static String`	`encodeObject(Serializable serializableObject)` Serializes an object and returns the Base64-encoded version of that serialized object.
`static String`	`encodeObject(Serializable serializableObject, int options)` Serializes an object and returns the Base64-encoded version of that serialized object.
`static void`	`encodeToFile(byte[] dataToEncode, String filename)` Convenience method for encoding data to a file.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - NO_OPTIONS
```
public static final int NO_OPTIONS
```
    No options specified. Value is zero.
    
    See Also:
    Constant Field Values
  - ENCODE
```
public static final int ENCODE
```
    Specify encoding in first bit. Value is one.
    
    See Also:
    Constant Field Values
  - DECODE
```
public static final int DECODE
```
    Specify decoding in first bit. Value is zero.
    
    See Also:
    Constant Field Values
  - GZIP
```
public static final int GZIP
```
    Specify that data should be gzip-compressed in second bit. Value is two.
    
    See Also:
    Constant Field Values
  - DO_BREAK_LINES
```
public static final int DO_BREAK_LINES
```
    Do break lines when encoding. Value is 8.
    
    See Also:
    Constant Field Values
  - URL_SAFE
```
public static final int URL_SAFE
```
    Encode using Base64-like encoding that is URL- and Filename-safe as described in Section 4 of RFC3548: http://www.faqs.org/rfcs/rfc3548.html. It is important to note that data encoded this way is not officially valid Base64, or at the very least should not be called Base64 without also specifying that is was encoded using the URL- and Filename-safe dialect.
    
    See Also:
    Constant Field Values
  - ORDERED
```
public static final int ORDERED
```
    Encode using the special "ordered" dialect of Base64 described here: http://www.faqs.org/qa/rfcc-1940.html.
    
    See Also:
    Constant Field Values
- Method Detail
  - encode
```
public static void encode(ByteBuffer raw,
          ByteBuffer encoded)
```
    Performs Base64 encoding on the raw ByteBuffer, writing it to the encoded ByteBuffer. This is an experimental feature. Currently it does not pass along any options (such as DO_BREAK_LINES or GZIP.
    
    Parameters:
    raw - input buffer
    encoded - output buffer
    Since:
    
    2.3
  - encode
```
public static void encode(ByteBuffer raw,
          CharBuffer encoded)
```
    Performs Base64 encoding on the raw ByteBuffer, writing it to the encoded CharBuffer. This is an experimental feature. Currently it does not pass along any options (such as DO_BREAK_LINES or GZIP.
    
    Parameters:
    raw - input buffer
    encoded - output buffer
    Since:
    
    2.3
  - encodeObject
```
public static String encodeObject(Serializable serializableObject)
                           throws IOException
```
    Serializes an object and returns the Base64-encoded version of that serialized object.
    
    As of v 2.3, if the object cannot be serialized or there is another error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned a null value, but in retrospect that's a pretty poor way to handle it.
    
    The object is not GZip-compressed before being encoded.
    
    Parameters:
    serializableObject - The object to encode
    
    Returns:
    The Base64-encoded object
    
    Throws:
    
    IOException - if there is an error
    
    NullPointerException - if serializedObject is null
    Since:
    
    1.4
  - encodeObject
```
public static String encodeObject(Serializable serializableObject,
                  int options)
                           throws IOException
```
    Serializes an object and returns the Base64-encoded version of that serialized object.
    
    As of v 2.3, if the object cannot be serialized or there is another error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned a null value, but in retrospect that's a pretty poor way to handle it.
    
    The object is not GZip-compressed before being encoded.
    Example options:
```
   GZIP: gzip-compresses object before encoding it.
   DO_BREAK_LINES: break lines at 76 characters
 
```
    Example: encodeObject( myObj, Base64.GZIP ) or
    Example: encodeObject( myObj, Base64.GZIP | Base64.DO_BREAK_LINES )
    Parameters:
    serializableObject - The object to encode
    options - Specified options
    
    Returns:
    The Base64-encoded object
    
    Throws:
    
    IOException - if there is an error
    Since:
    
    2.0
    
    See Also:
    GZIP, DO_BREAK_LINES
  - encodeBytes
```
public static String encodeBytes(byte[] source)
```
    Encodes a byte array into Base64 notation. Does not GZip-compress data.
    
    Parameters:
    source - The data to convert
    
    Returns:
    The data in Base64-encoded form
    
    Throws:
    
    NullPointerException - if source array is null
    Since:
    
    1.4
  - encodeBytes
```
public static String encodeBytes(byte[] source,
                 int options)
                          throws IOException
```
    Encodes a byte array into Base64 notation.
    Example options:
```
   GZIP: gzip-compresses object before encoding it.
   DO_BREAK_LINES: break lines at 76 characters
     <i>Note: Technically, this makes your encoding non-compliant.</i>
 
```
    Example: encodeBytes( myData, Base64.GZIP ) or
    Example: encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )
    
    As of v 2.3, if there is an error with the GZIP stream, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned a null value, but in retrospect that's a pretty poor way to handle it.
    Parameters:
    source - The data to convert
    options - Specified options
    
    Returns:
    The Base64-encoded data as a String
    
    Throws:
    
    IOException - if there is an error
    
    NullPointerException - if source array is null
    Since:
    
    2.0
    
    See Also:
    GZIP, DO_BREAK_LINES
  - encodeBytes
```
public static String encodeBytes(byte[] source,
                 int off,
                 int len)
```
    Encodes a byte array into Base64 notation. Does not GZip-compress data.
    
    As of v 2.3, if there is an error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned a null value, but in retrospect that's a pretty poor way to handle it.
    
    Parameters:
    source - The data to convert
    off - Offset in array where conversion should begin
    len - Length of data to convert
    
    Returns:
    The Base64-encoded data as a String
    
    Throws:
    
    NullPointerException - if source array is null
    
    IllegalArgumentException - if source array, offset, or length are invalid
    Since:
    
    1.4
  - encodeBytes
```
public static String encodeBytes(byte[] source,
                 int off,
                 int len,
                 int options)
                          throws IOException
```
    Encodes a byte array into Base64 notation.
    Example options:
```
   GZIP: gzip-compresses object before encoding it.
   DO_BREAK_LINES: break lines at 76 characters
     <i>Note: Technically, this makes your encoding non-compliant.</i>
 
```
    Example: encodeBytes( myData, Base64.GZIP ) or
    Example: encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )
    
    As of v 2.3, if there is an error with the GZIP stream, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned a null value, but in retrospect that's a pretty poor way to handle it.
    Parameters:
    source - The data to convert
    off - Offset in array where conversion should begin
    len - Length of data to convert
    options - Specified options
    
    Returns:
    The Base64-encoded data as a String
    
    Throws:
    
    IOException - if there is an error
    
    NullPointerException - if source array is null
    
    IllegalArgumentException - if source array, offset, or length are invalid
    Since:
    
    2.0
    
    See Also:
    GZIP, DO_BREAK_LINES
  - encodeBytesToBytes
```
public static byte[] encodeBytesToBytes(byte[] source)
```
    Similar to encodeBytes(byte[]) but returns a byte array instead of instantiating a String. This is more efficient if you're working with I/O streams and have large data sets to encode.
    
    Parameters:
    source - The data to convert
    
    Returns:
    The Base64-encoded data as a byte[] (of ASCII characters)
    
    Throws:
    
    NullPointerException - if source array is null
    Since:
    
    2.3.1
  - encodeBytesToBytes
```
public static byte[] encodeBytesToBytes(byte[] source,
                        int off,
                        int len,
                        int options)
                                 throws IOException
```
    Similar to encodeBytes(byte[], int, int, int) but returns a byte array instead of instantiating a String. This is more efficient if you're working with I/O streams and have large data sets to encode.
    
    Parameters:
    source - The data to convert
    off - Offset in array where conversion should begin
    len - Length of data to convert
    options - Specified options
    
    Returns:
    The Base64-encoded data as a String
    
    Throws:
    
    IOException - if there is an error
    
    NullPointerException - if source array is null
    
    IllegalArgumentException - if source array, offset, or length are invalid
    Since:
    
    2.3.1
    
    See Also:
    GZIP, DO_BREAK_LINES
  - decode
```
public static byte[] decode(byte[] source)
```
    Low-level access to decoding ASCII characters in the form of a byte array. Ignores GUNZIP option, if it's set. This is not generally a recommended method, although it is used internally as part of the decoding process. Special case: if len = 0, an empty array is returned. Still, if you need more quantity and reduced memory footprint (and aren't gzipping), consider this method.
    
    Parameters:
    source - The Base64 encoded data
    
    Returns:
    decoded data
    Since:
    
    2.3.1
  - decode
```
public static byte[] decode(byte[] source,
            int off,
            int len,
            int options)
                     throws IOException
```
    Low-level access to decoding ASCII characters in the form of a byte array. Ignores GUNZIP option, if it's set. This is not generally a recommended method, although it is used internally as part of the decoding process. Special case: if len = 0, an empty array is returned. Still, if you need more quantity and reduced memory footprint (and aren't gzipping), consider this method.
    
    Parameters:
    source - The Base64 encoded data
    off - The offset of where to begin decoding
    len - The length of characters to decode
    options - Can specify options such as alphabet type to use
    
    Returns:
    decoded data
    
    Throws:
    
    IOException - If bogus characters exist in source data
    Since:
    
    1.3
  - decode
```
public static byte[] decode(String s)
                     throws IOException
```
    Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
    
    Parameters:
    s - the string to decode
    
    Returns:
    the decoded data
    
    Throws:
    
    IOException - If there is a problem
    Since:
    
    1.4
  - decode
```
public static byte[] decode(String s,
            int options)
                     throws IOException
```
    Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
    
    Parameters:
    s - the string to decode
    options - encode options such as URL_SAFE
    
    Returns:
    the decoded data
    
    Throws:
    
    IOException - if there is an error
    
    NullPointerException - if s is null
    Since:
    
    1.4
  - decodeToObject
```
public static Object decodeToObject(String encodedObject)
                             throws IOException,
                                    ClassNotFoundException
```
    Attempts to decode Base64 data and deserialize a Java Object within. Returns null if there was an error.
    
    Parameters:
    encodedObject - The Base64 data to decode
    
    Returns:
    The decoded and deserialized object
    
    Throws:
    
    NullPointerException - if encodedObject is null
    
    IOException - if there is a general error
    
    ClassNotFoundException - if the decoded object is of a class that cannot be found by the JVM
    Since:
    
    1.5
  - encodeToFile
```
public static void encodeToFile(byte[] dataToEncode,
                String filename)
                         throws IOException
```
    Convenience method for encoding data to a file.
    
    As of v 2.3, if there is a error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned false, but in retrospect that's a pretty poor way to handle it.
    
    Parameters:
    dataToEncode - byte array of data to encode in base64 form
    filename - Filename for saving encoded data
    
    Throws:
    
    IOException - if there is an error
    
    NullPointerException - if dataToEncode is null
    Since:
    
    2.1
  - decodeToFile
```
public static void decodeToFile(String dataToDecode,
                String filename)
                         throws IOException
```
    Convenience method for decoding data to a file.
    
    As of v 2.3, if there is a error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned false, but in retrospect that's a pretty poor way to handle it.
    
    Parameters:
    dataToDecode - Base64-encoded data as a string
    filename - Filename for saving decoded data
    
    Throws:
    
    IOException - if there is an error
    Since:
    
    2.1
  - decodeFromFile
```
public static byte[] decodeFromFile(String filename)
                             throws IOException
```
    Convenience method for reading a base64-encoded file and decoding it.
    
    As of v 2.3, if there is a error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned false, but in retrospect that's a pretty poor way to handle it.
    
    Parameters:
    filename - Filename for reading encoded data
    
    Returns:
    decoded byte array
    
    Throws:
    
    IOException - if there is an error
    Since:
    
    2.1
  - encodeFromFile
```
public static String encodeFromFile(String filename)
                             throws IOException
```
    Convenience method for reading a binary file and base64-encoding it.
    
    As of v 2.3, if there is a error, the method will throw an java.io.IOException. This is new to v2.3! In earlier versions, it just returned false, but in retrospect that's a pretty poor way to handle it.
    
    Parameters:
    filename - Filename for reading binary data
    
    Returns:
    base64-encoded string
    
    Throws:
    
    IOException - if there is an error
    Since:
    
    2.1
  - encodeFileToFile
```
public static void encodeFileToFile(String infile,
                    String outfile)
                             throws IOException
```
    Reads infile and encodes it to outfile.
    
    Parameters:
    infile - Input file
    outfile - Output file
    
    Throws:
    
    IOException - if there is an error
    Since:
    
    2.2
  - decodeFileToFile
```
public static void decodeFileToFile(String infile,
                    String outfile)
                             throws IOException
```
    Reads infile and decodes it to outfile.
    
    Parameters:
    infile - Input file
    outfile - Output file
    
    Throws:
    
    IOException - if there is an error
    Since:
    
    2.2

Class Base64

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NO_OPTIONS

ENCODE

DECODE

GZIP

DO_BREAK_LINES

URL_SAFE

ORDERED

Method Detail

encode

encode

encodeObject

encodeObject

encodeBytes

encodeBytes

encodeBytes

encodeBytes

encodeBytesToBytes

encodeBytesToBytes

decode

decode

decode

decode

decodeToObject

encodeToFile

decodeToFile

decodeFromFile

encodeFromFile

encodeFileToFile

decodeFileToFile