用Java解码Base64数据
我有一个Base64编码的图像。 在Java中解码的最好方法是什么？ 希望只使用Sun Java 6附带的库。
从第6版开始，Java SE随JAXB一起提供。 javax.xml.bind.DatatypeConverter有一个简单的静态方法。 请参阅parseBase64Binary()和printBase64Binary() 。
从Java 8开始 ，有一个官方支持的Base64编码和解码API。 这可能会成为默认的select。
该API包括类java.util.Base64及其嵌套类。 它支持三种不同的风格：基本，URL安全和MIME。
使用“基本”编码的示例代码：
import java.util.Base64; byte[] bytes = "Hello, World!".getBytes("UTF-8"); String encoded = Base64.getEncoder().encodeToString(bytes); byte[] decoded = Base64.getDecoder().decode(encoded);
java.util.Base64的文档包含了更多的configuration编码器和解码器的方法，以及使用不同的类作为input和输出（字节数组，string，ByteBuffers，java.iostream）的方法。
这是一个使用Apache Commons编解码器的工作示例：
import org.apache.commons.codec.binary.Base64; import org.apache.commons.codec.binary.StringUtils; public String decode(String s) { return StringUtils.newStringUtf8(Base64.decodeBase64(s)); } public String encode(String s) { return Base64.encodeBase64String(StringUtils.getBytesUtf8(s)); }
Maven / sbt回购：commons-codec，commons-codec，1.8。
不需要使用commons – Sun公司发布了一个带有Java的base64编码器。 你可以像这样导入它：
import sun.misc.BASE64Decoder;
然后像这样使用它：
BASE64Decoder decoder = new BASE64Decoder(); byte[] decodedBytes = decoder.decodeBuffer(encodedBytes);
其中encodedBytes是java.lang.String或java.io.InputStream 。 请注意， sun.*课程并不受Sun的“正式支持”。
编辑：谁知道这将是我曾经发表的最有争议的答案？ 我知道太阳。*软件包不被支持或保证继续存在，我知道Commons并且一直使用它。 但是，海报要求提供一个“包含在Sun Java 6中”的课程，这就是我想要回答的问题。 我同意下议院是一般的最佳途径。
编辑2：正如下面amir75指出的那样，Java 6+附带了JAXB，其中包含支持的Base64编码/解码代码。 请看下面的杰里米·罗斯的答案 。
具体在Commons Codec中 ：class Base64 decode(byte[] array)或encode(byte[] array)
番石榴现在有内置的Base64解码。
使用BaseEncoding.base64（）。decode（）
至于在input使用中处理可能的空白
BaseEncoding.base64().decode(CharMatcher.WHITESPACE.removeFrom(...));
有关更多信息，请参阅此讨论
我的解决scheme是最快，最简单的。
public class MyBase64 { private final static char[] ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray(); private static int[] toInt = new int[128]; static { for(int i=0; i< ALPHABET.length; i++){ toInt[ALPHABET[i]]= i; } } /** * Translates the specified byte array into Base64 string. * * @param buf the byte array (not null) * @return the translated Base64 string (not null) */ public static String encode(byte[] buf){ int size = buf.length; char[] ar = new char[((size + 2) / 3) * 4]; int a = 0; int i=0; while(i < size){ byte b0 = buf[i++]; byte b1 = (i < size) ? buf[i++] : 0; byte b2 = (i < size) ? buf[i++] : 0; int mask = 0x3F; ar[a++] = ALPHABET[(b0 >> 2) & mask]; ar[a++] = ALPHABET[((b0 << 4) | ((b1 & 0xFF) >> 4)) & mask]; ar[a++] = ALPHABET[((b1 << 2) | ((b2 & 0xFF) >> 6)) & mask]; ar[a++] = ALPHABET[b2 & mask]; } switch(size % 3){ case 1: ar[--a] = '='; case 2: ar[--a] = '='; } return new String(ar); } /** * Translates the specified Base64 string into a byte array. * * @param s the Base64 string (not null) * @return the byte array (not null) */ public static byte[] decode(String s){ int delta = s.endsWith( "==" ) ? 2 : s.endsWith( "=" ) ? 1 : 0; byte[] buffer = new byte[s.length()*3/4 - delta]; int mask = 0xFF; int index = 0; for(int i=0; i< s.length(); i+=4){ int c0 = toInt[s.charAt( i )]; int c1 = toInt[s.charAt( i + 1)]; buffer[index++]= (byte)(((c0 << 2) | (c1 >> 4)) & mask); if(index >= buffer.length){ return buffer; } int c2 = toInt[s.charAt( i + 2)]; buffer[index++]= (byte)(((c1 << 4) | (c2 >> 2)) & mask); if(index >= buffer.length){ return buffer; } int c3 = toInt[s.charAt( i + 3 )]; buffer[index++]= (byte)(((c2 << 6) | c3) & mask); } return buffer; } }
这是我自己的实现，如果它可能对某人有用：
public class Base64Coder { // The line separator string of the operating system. private static final String systemLineSeparator = System.getProperty("line.separator"); // Mapping table from 6-bit nibbles to Base64 characters. private static final char[] map1 = new char[64]; static { int i=0; for (char c='A'; c<='Z'; c++) map1[i++] = c; for (char c='a'; c<='z'; c++) map1[i++] = c; for (char c='0'; c<='9'; c++) map1[i++] = c; map1[i++] = '+'; map1[i++] = '/'; } // Mapping table from Base64 characters to 6-bit nibbles. private static final byte[] map2 = new byte[128]; static { for (int i=0; i<map2.length; i++) map2[i] = -1; for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; } /** * Encodes a string into Base64 format. * No blanks or line breaks are inserted. * @param s A String to be encoded. * @return A String containing the Base64 encoded data. */ public static String encodeString (String s) { return new String(encode(s.getBytes())); } /** * Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters. * This method is compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>. * @param in An array containing the data bytes to be encoded. * @return A String containing the Base64 encoded data, broken into lines. */ public static String encodeLines (byte[] in) { return encodeLines(in, 0, in.length, 76, systemLineSeparator); } /** * Encodes a byte array into Base 64 format and breaks the output into lines. * @param in An array containing the data bytes to be encoded. * @param iOff Offset of the first byte in <code>in</code> to be processed. * @param iLen Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>. * @param lineLen Line length for the output data. Should be a multiple of 4. * @param lineSeparator The line separator to be used to separate the output lines. * @return A String containing the Base64 encoded data, broken into lines. */ public static String encodeLines (byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) { int blockLen = (lineLen*3) / 4; if (blockLen <= 0) throw new IllegalArgumentException(); int lines = (iLen+blockLen-1) / blockLen; int bufLen = ((iLen+2)/3)*4 + lines*lineSeparator.length(); StringBuilder buf = new StringBuilder(bufLen); int ip = 0; while (ip < iLen) { int l = Math.min(iLen-ip, blockLen); buf.append (encode(in, iOff+ip, l)); buf.append (lineSeparator); ip += l; } return buf.toString(); } /** * Encodes a byte array into Base64 format. * No blanks or line breaks are inserted in the output. * @param in An array containing the data bytes to be encoded. * @return A character array containing the Base64 encoded data. */ public static char[] encode (byte[] in) { return encode(in, 0, in.length); } /** * Encodes a byte array into Base64 format. * No blanks or line breaks are inserted in the output. * @param in An array containing the data bytes to be encoded. * @param iLen Number of bytes to process in <code>in</code>. * @return A character array containing the Base64 encoded data. */ public static char[] encode (byte[] in, int iLen) { return encode(in, 0, iLen); } /** * Encodes a byte array into Base64 format. * No blanks or line breaks are inserted in the output. * @param in An array containing the data bytes to be encoded. * @param iOff Offset of the first byte in <code>in</code> to be processed. * @param iLen Number of bytes to process in <code>in</code>, starting at <code>iOff</code>. * @return A character array containing the Base64 encoded data. */ public static char[] encode (byte[] in, int iOff, int iLen) { int oDataLen = (iLen*4+2)/3; // output length without padding int oLen = ((iLen+2)/3)*4; // output length including padding char[] out = new char[oLen]; int ip = iOff; int iEnd = iOff + iLen; int op = 0; while (ip < iEnd) { int i0 = in[ip++] & 0xff; int i1 = ip < iEnd ? in[ip++] & 0xff : 0; int i2 = ip < iEnd ? in[ip++] & 0xff : 0; int o0 = i0 >>> 2; int o1 = ((i0 & 3) << 4) | (i1 >>> 4); int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6); int o3 = i2 & 0x3F; out[op++] = map1[o0]; out[op++] = map1[o1]; out[op] = op < oDataLen ? map1[o2] : '='; op++; out[op] = op < oDataLen ? map1[o3] : '='; op++; } return out; } /** * Decodes a string from Base64 format. * No blanks or line breaks are allowed within the Base64 encoded input data. * @param s A Base64 String to be decoded. * @return A String containing the decoded data. * @throws IllegalArgumentException If the input is not valid Base64 encoded data. */ public static String decodeString (String s) { return new String(decode(s)); } /** * Decodes a byte array from Base64 format and ignores line separators, tabs and blanks. * CR, LF, Tab and Space characters are ignored in the input data. * This method is compatible with <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>. * @param s A Base64 String to be decoded. * @return An array containing the decoded data bytes. * @throws IllegalArgumentException If the input is not valid Base64 encoded data. */ public static byte[] decodeLines (String s) { char[] buf = new char[s.length()]; int p = 0; for (int ip = 0; ip < s.length(); ip++) { char c = s.charAt(ip); if (c != ' ' && c != '\r' && c != '\n' && c != '\t') buf[p++] = c; } return decode(buf, 0, p); } /** * Decodes a byte array from Base64 format. * No blanks or line breaks are allowed within the Base64 encoded input data. * @param s A Base64 String to be decoded. * @return An array containing the decoded data bytes. * @throws IllegalArgumentException If the input is not valid Base64 encoded data. */ public static byte[] decode (String s) { return decode(s.toCharArray()); } /** * Decodes a byte array from Base64 format. * No blanks or line breaks are allowed within the Base64 encoded input data. * @param in A character array containing the Base64 encoded data. * @return An array containing the decoded data bytes. * @throws IllegalArgumentException If the input is not valid Base64 encoded data. */ public static byte[] decode (char[] in) { return decode(in, 0, in.length); } /** * Decodes a byte array from Base64 format. * No blanks or line breaks are allowed within the Base64 encoded input data. * @param in A character array containing the Base64 encoded data. * @param iOff Offset of the first character in <code>in</code> to be processed. * @param iLen Number of characters to process in <code>in</code>, starting at <code>iOff</code>. * @return An array containing the decoded data bytes. * @throws IllegalArgumentException If the input is not valid Base64 encoded data. */ public static byte[] decode (char[] in, int iOff, int iLen) { if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4."); while (iLen > 0 && in[iOff+iLen-1] == '=') iLen--; int oLen = (iLen*3) / 4; byte[] out = new byte[oLen]; int ip = iOff; int iEnd = iOff + iLen; int op = 0; while (ip < iEnd) { int i0 = in[ip++]; int i1 = in[ip++]; int i2 = ip < iEnd ? in[ip++] : 'A'; int i3 = ip < iEnd ? in[ip++] : 'A'; if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127) throw new IllegalArgumentException ("Illegal character in Base64 encoded data."); int b0 = map2[i0]; int b1 = map2[i1]; int b2 = map2[i2]; int b3 = map2[i3]; if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0) throw new IllegalArgumentException ("Illegal character in Base64 encoded data."); int o0 = ( b0 <<2) | (b1>>>4); int o1 = ((b1 & 0xf)<<4) | (b2>>>2); int o2 = ((b2 & 3)<<6) | b3; out[op++] = (byte)o0; if (op<oLen) out[op++] = (byte)o1; if (op<oLen) out[op++] = (byte)o2; } return out; } // Dummy constructor. private Base64Coder() {} }
作为sun.misc.BASE64Decoder或非核心库的替代方法，请sun.misc.BASE64Decoder javax.mail.internet.MimeUtility.decode() 。
JIST：
public static byte[] encode(byte[] b) throws Exception { ByteArrayOutputStream baos = new ByteArrayOutputStream(); OutputStream b64os = MimeUtility.encode(baos, "base64"); b64os.write(b); b64os.close(); return baos.toByteArray(); } public static byte[] decode(byte[] b) throws Exception { ByteArrayInputStream bais = new ByteArrayInputStream(b); InputStream b64is = MimeUtility.decode(bais, "base64"); byte[] tmp = new byte[b.length]; int n = b64is.read(tmp); byte[] res = new byte[n]; System.arraycopy(tmp, 0, res, 0, n); return res; }
链接与完整的代码： 编码/解码到/从Base64
给出一个使用parseBase64Binary（）和printBase64Binary（）引用@ jeremy-ross和@nightfirecat答案的javax.xml.bind.DatatypeConverter的testing编码/解码示例。
@Test public void EncodeDecode() { //ENCODE String hello = "Hello World"; byte[] helloBytes = hello.getBytes(StandardCharsets.UTF_8); String encodedHello = DatatypeConverter.printBase64Binary(helloBytes); LOGGER.info(hello + " encoded=> " + encodedHello); //DECODE byte[] encodedHelloBytes = DatatypeConverter.parseBase64Binary(encodedHello); String helloAgain = new String(encodedHelloBytes, StandardCharsets.UTF_8) ; LOGGER.info(encodedHello + " decoded=> " + helloAgain); Assert.assertEquals(hello, helloAgain); }
结果：
INFO - Hello World encoded=> SGVsbG8gV29ybGQ= INFO - SGVsbG8gV29ybGQ= decoded=> Hello World
另一个迟到的答案，但我的基准testing表明， Jetty的Base64编码器的实施是相当快的。 不如MiGBase64快，但比iHarder Base64快。
import org.eclipse.jetty.util.B64Code; final String decoded = B64Code.decode(encoded, "UTF-8");
我也做了一些基准：
library | encode | decode ------------------+--------------+------------- 'MiGBase64' | 10146001.00 | 6426446.00 'Jetty B64Code' | 8846191.00 | 3101361.75 'iHarder Base64' | 3259590.50 | 2505280.00 'Commons-Codec' | 241318.04 | 255179.96
这些是每秒运行，所以越高越好。
如果您偏好基于性能的解决scheme，那么您可以使用“MiGBase64”
http://migbase64.sourceforge.net/
public class Base64Test { public static void main(String[] args) { String encodeToString = Base64.encodeToString("JavaTips.net".getBytes(), true); System.out.println("encodeToString " + encodeToString); byte[] decodedBytes = Base64.decode(encodeToString.getBytes()); System.out.println("decodedBytes " + new String(decodedBytes)); } }
希望这可以帮助你：
import com.sun.org.apache.xml.internal.security.utils.Base64; String str="Hello World"; String base64_str=Base64.encode(str.getBytes("UTF-8"));
要么：
String str="Hello World"; String base64_str=""; try {base64_str=(String)Class.forName("java.util.prefs.Base64").getDeclaredMethod("byteArrayToBase64", new Class[]{byte[].class}).invoke(null, new Object[]{str.getBytes("UTF-8")}); } catch (Exception ee) {}
java.util.prefs.Base64在本地rt.jar ，
但它不在JRE类白名单中
而不在GAE / J白名单中未列出的可用class级中
太遗憾了！
PS。 在android中，这很容易，因为android.util.Base64已经被包含在Android API Level 8之后。
这是一个迟到的答案，但是Joshua Bloch在java.util.prefs包下面做了他的Base64类（当他在Sun，ahem，Oracle工作时）。 这个类从JDK 1.4开始就存在了。
例如
String currentString = "Hello World"; String base64String = java.util.prefs.Base64.byteArrayToBase64(currentString.getBytes("UTF-8"));
您可以编写或从编码的Base64string下载文件：
Base64 base64 = new Base64(); String encodedFile="JVBERi0xLjUKJeLjz9MKMSAwIG9iago8PCAKICAgL1R5cGUgL0NhdGFsb2cKICAgL1BhZ2VzIDIgMCBSCiAgIC9QYWdlTGF5b3V0IC9TaW5"; byte[] dd=encodedFile.getBytes(); byte[] bytes = Base64.decodeBase64(dd); response.setHeader("Content-disposition", "attachment; filename=\""+filename+"\""); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Expires", "-1"); // actually send result bytes response.getOutputStream().write(bytes);
为我工作，希望为你也…
如果您已经添加了适用于Java的AWS开发工具包 ，则可以使用com.amazonaws.util.Base64 。
java.util.Base64的Java 8实现不依赖于其他Java 8特定的类。
我不确定这是否适用于Java 6项目，但是可以将Base64.java文件复制并粘贴到Java 7项目中，除了导入java.util.Arrays和java.util.Objects之外，无需修改即可编译它java.util.Objects 。
注意Base64.java文件被GNU GPL2覆盖
我使用的android.util.base64没有任何依赖的工作相当不错：
用法：
byte[] decodedKey = Base64.decode(encodedPublicKey, Base64.DEFAULT);
包com.test;
import java.io.UnsupportedEncodingException; /** * Utilities for encoding and decoding the Base64 representation of * binary data. See RFCs <a * href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and <a * href="http://www.ietf.org/rfc/rfc3548.txt">3548</a>. */ public class Base64 { public static final int DEFAULT = 0; public static final int NO_PADDING = 1; public static final int NO_WRAP = 2; public static final int CRLF = 4; public static final int URL_SAFE = 8; public static final int NO_CLOSE = 16; // -------------------------------------------------------- // shared code // -------------------------------------------------------- /* package */ static abstract class Coder { public byte[] output; public int op; public abstract boolean process(byte[] input, int offset, int len, boolean finish); public abstract int maxOutputSize(int len); } // -------------------------------------------------------- // decoding // -------------------------------------------------------- public static byte[] decode(String str, int flags) { return decode(str.getBytes(), flags); } public static byte[] decode(byte[] input, int flags) { return decode(input, 0, input.length, flags); } public static byte[] decode(byte[] input, int offset, int len, int flags) { // Allocate space for the most data the input could represent. // (It could contain less if it contains whitespace, etc.) Decoder decoder = new Decoder(flags, new byte[len*3/4]); if (!decoder.process(input, offset, len, true)) { throw new IllegalArgumentException("bad base-64"); } // Maybe we got lucky and allocated exactly enough output space. if (decoder.op == decoder.output.length) { return decoder.output; } // Need to shorten the array, so allocate a new one of the // right size and copy. byte[] temp = new byte[decoder.op]; System.arraycopy(decoder.output, 0, temp, 0, decoder.op); return temp; } static class Decoder extends Coder { private static final int DECODE[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, }; /** * Decode lookup table for the "web safe" variant (RFC 3548 * sec. 4) where - and _ replace + and /. */ private static final int DECODE_WEBSAFE[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, }; /** Non-data values in the DECODE arrays. */ private static final int SKIP = -1; private static final int EQUALS = -2; private int state; // state number (0 to 6) private int value; final private int[] alphabet; public Decoder(int flags, byte[] output) { this.output = output; alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE; state = 0; value = 0; } public int maxOutputSize(int len) { return len * 3/4 + 10; } /** * Decode another block of input data. * * @return true if the state machine is still healthy. false if * bad base-64 data has been detected in the input stream. */ public boolean process(byte[] input, int offset, int len, boolean finish) { if (this.state == 6) return false; int p = offset; len += offset; int state = this.state; int value = this.value; int op = 0; final byte[] output = this.output; final int[] alphabet = this.alphabet; while (p < len) { if (state == 0) { while (p+4 <= len && (value = ((alphabet[input[p] & 0xff] << 18) | (alphabet[input[p+1] & 0xff] << 12) | (alphabet[input[p+2] & 0xff] << 6) | (alphabet[input[p+3] & 0xff]))) >= 0) { output[op+2] = (byte) value; output[op+1] = (byte) (value >> 8); output[op] = (byte) (value >> 16); op += 3; p += 4; } if (p >= len) break; } int d = alphabet[input[p++] & 0xff]; switch (state) { case 0: if (d >= 0) { value = d; ++state; } else if (d != SKIP) { this.state = 6; return false; } break; case 1: if (d >= 0) { value = (value << 6) | d; ++state; } else if (d != SKIP) { this.state = 6; return false; } break; case 2: if (d >= 0) { value = (value << 6) | d; ++state; } else if (d == EQUALS) { // Emit the last (partial) output tuple; // expect exactly one more padding character. output[op++] = (byte) (value >> 4); state = 4; } else if (d != SKIP) { this.state = 6; return false; } break; case 3: if (d >= 0) { // Emit the output triple and return to state 0. value = (value << 6) | d; output[op+2] = (byte) value; output[op+1] = (byte) (value >> 8); output[op] = (byte) (value >> 16); op += 3; state = 0; } else if (d == EQUALS) { // Emit the last (partial) output tuple; // expect no further data or padding characters. output[op+1] = (byte) (value >> 2); output[op] = (byte) (value >> 10); op += 2; state = 5; } else if (d != SKIP) { this.state = 6; return false; } break; case 4: if (d == EQUALS) { ++state; } else if (d != SKIP) { this.state = 6; return false; } break; case 5: if (d != SKIP) { this.state = 6; return false; } break; } } if (!finish) { // We're out of input, but a future call could provide // more. this.state = state; this.value = value; this.op = op; return true; } switch (state) { case 0: break; case 1: this.state = 6; return false; case 2: output[op++] = (byte) (value >> 4); break; case 3: output[op++] = (byte) (value >> 10); output[op++] = (byte) (value >> 2); break; case 4: this.state = 6; return false; case 5: break; } this.state = state; this.op = op; return true; } } // -------------------------------------------------------- // encoding // -------------------------------------------------------- public static String encodeToString(byte[] input, int flags) { try { return new String(encode(input, flags), "US-ASCII"); } catch (UnsupportedEncodingException e) { // US-ASCII is guaranteed to be available. throw new AssertionError(e); } } public static String encodeToString(byte[] input, int offset, int len, int flags) { try { return new String(encode(input, offset, len, flags), "US-ASCII"); } catch (UnsupportedEncodingException e) { // US-ASCII is guaranteed to be available. throw new AssertionError(e); } } public static byte[] encode(byte[] input, int flags) { return encode(input, 0, input.length, flags); } public static byte[] encode(byte[] input, int offset, int len, int flags) { Encoder encoder = new Encoder(flags, null); // Compute the exact length of the array we will produce. int output_len = len / 3 * 4; // Account for the tail of the data and the padding bytes, if any. if (encoder.do_padding) { if (len % 3 > 0) { output_len += 4; } } else { switch (len % 3) { case 0: break; case 1: output_len += 2; break; case 2: output_len += 3; break; } } // Account for the newlines, if any. if (encoder.do_newline && len > 0) { output_len += (((len-1) / (3 * Encoder.LINE_GROUPS)) + 1) * (encoder.do_cr ? 2 : 1); } encoder.output = new byte[output_len]; encoder.process(input, offset, len, true); assert encoder.op == output_len; return encoder.output; } /* package */ static class Encoder extends Coder { /** * Emit a new line every this many output tuples. Corresponds to * a 76-character line length (the maximum allowable according to * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>). */ public static final int LINE_GROUPS = 19; /** * Lookup table for turning Base64 alphabet positions (6 bits) * into output bytes. */ private static final byte ENCODE[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', }; /** * Lookup table for turning Base64 alphabet positions (6 bits) * into output bytes. */ private static final byte ENCODE_WEBSAFE[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_', }; final private byte[] tail; /* package */ int tailLen; private int count; final public boolean do_padding; final public boolean do_newline; final public boolean do_cr; final private byte[] alphabet; public Encoder(int flags, byte[] output) { this.output = output; do_padding = (flags & NO_PADDING) == 0; do_newline = (flags & NO_WRAP) == 0; do_cr = (flags & CRLF) != 0; alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE; tail = new byte[2]; tailLen = 0; count = do_newline ? LINE_GROUPS : -1; } /** * @return an overestimate for the number of bytes {@code * len} bytes could encode to. */ public int maxOutputSize(int len) { return len * 8/5 + 10; } public boolean process(byte[] input, int offset, int len, boolean finish) { // Using local variables makes the encoder about 9% faster. final byte[] alphabet = this.alphabet; final byte[] output = this.output; int op = 0; int count = this.count; int p = offset; len += offset; int v = -1; // First we need to concatenate the tail of the previous call // with any input bytes available now and see if we can empty // the tail. switch (tailLen) { case 0: // There was no tail. break; case 1: if (p+2 <= len) { // A 1-byte tail with at least 2 bytes of // input available now. v = ((tail[0] & 0xff) << 16) | ((input[p++] & 0xff) << 8) | (input[p++] & 0xff); tailLen = 0; }; break; case 2: if (p+1 <= len) { // A 2-byte tail with at least 1 byte of input. v = ((tail[0] & 0xff) << 16) | ((tail[1] & 0xff) << 8) | (input[p++] & 0xff); tailLen = 0; } break; } if (v != -1) { output[op++] = alphabet[(v >> 18) & 0x3f]; output[op++] = alphabet[(v >> 12) & 0x3f]; output[op++] = alphabet[(v >> 6) & 0x3f]; output[op++] = alphabet[v & 0x3f]; if (--count == 0) { if (do_cr) output[op++] = '\r'; output[op++] = '\n'; count = LINE_GROUPS; } } // At this point either there is no tail, or there are fewer // than 3 bytes of input available. // The main loop, turning 3 input bytes into 4 output bytes on // each iteration. while (p+3 <= len) { v = ((input[p] & 0xff) << 16) | ((input[p+1] & 0xff) << 8) | (input[p+2] & 0xff); output[op] = alphabet[(v >> 18) & 0x3f]; output[op+1] = alphabet[(v >> 12) & 0x3f]; output[op+2] = alphabet[(v >> 6) & 0x3f]; output[op+3] = alphabet[v & 0x3f]; p += 3; op += 4; if (--count == 0) { if (do_cr) output[op++] = '\r'; output[op++] = '\n'; count = LINE_GROUPS; } } if (finish) { if (p-tailLen == len-1) { int t = 0; v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4; tailLen -= t; output[op++] = alphabet[(v >> 6) & 0x3f]; output[op++] = alphabet[v & 0x3f]; if (do_padding) { output[op++] = '='; output[op++] = '='; } if (do_newline) { if (do_cr) output[op++] = '\r'; output[op++] = '\n'; } } else if (p-tailLen == len-2) { int t = 0; v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) | (((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2); tailLen -= t; output[op++] = alphabet[(v >> 12) & 0x3f]; output[op++] = alphabet[(v >> 6) & 0x3f]; output[op++] = alphabet[v & 0x3f]; if (do_padding) { output[op++] = '='; } if (do_newline) { if (do_cr) output[op++] = '\r'; output[op++] = '\n'; } } else if (do_newline && op > 0 && count != LINE_GROUPS) { if (do_cr) output[op++] = '\r'; output[op++] = '\n'; } assert tailLen == 0; assert p == len; } else { // Save the leftovers in tail to be consumed on the next // call to encodeInternal. if (p == len-1) { tail[tailLen++] = input[p]; } else if (p == len-2) { tail[tailLen++] = input[p]; tail[tailLen++] = input[p+1]; } } this.op = op; this.count = count; return true; } } private Base64() { } // don't instantiate }
