Base64Util工具类

import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.ByteArrayOutputStream;import java.io.CharArrayWriter;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.io.Reader;import java.io.Writer;public class Base64Util {        public Base64Util() {      }         /**      * 功能：编码字符串      * @param data      *      源字符串      * @return String      */      public static String encode(String data) {          return new String(encode(data.getBytes()));      }         /**      * 功能：解码字符串      * @param data      *      源字符串      * @return String      */      public static String decode(String data) {          return new String(decode(data.toCharArray()));      }         /**      * 功能：编码byte[]      * @param data      *      源      * @return char[]      */      public static char[] encode(byte[] data) {          char[] out = new char[((data.length + 2) / 3) * 4];          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;      }         /**      * 功能：解码      * @param data      *      编码后的字符数组      * @return byte[]      */      public static byte[] decode(char[] data) {             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);                  }              }          }             // 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;      }         /**      * 功能：编码文件      * @param file      *      源文件      */      public static void encode(File file) throws IOException {          if (!file.exists()) {              System.exit(0);          }             else {              byte[] decoded = readBytes(file);              char[] encoded = encode(decoded);              writeChars(file, encoded);          }          file = null;      }         /**      * 功能：解码文件。      * @param file      *      源文件      * @throws IOException      */      public static void decode(File file) throws IOException {          if (!file.exists()) {              System.exit(0);          } else {              char[] encoded = readChars(file);              byte[] decoded = decode(encoded);              writeBytes(file, decoded);          }          file = null;      }         //      // code characters for values 0..63      //      private static char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="              .toCharArray();         //      // lookup table for converting base64 characters to value in range 0..63      //      private static byte[] codes = new byte[256];      static {          for (int i = 0; i < 256; i++) {              codes[i] = -1;              // LoggerUtil.debug(i + "&" + codes[i] + " ");          }          for (int i = 'A'; i <= 'Z'; i++) {              codes[i] = (byte) (i - 'A');              // LoggerUtil.debug(i + "&" + codes[i] + " ");          }             for (int i = 'a'; i <= 'z'; i++) {              codes[i] = (byte) (26 + i - 'a');              // LoggerUtil.debug(i + "&" + codes[i] + " ");          }          for (int i = '0'; i <= '9'; i++) {              codes[i] = (byte) (52 + i - '0');              // LoggerUtil.debug(i + "&" + codes[i] + " ");          }          codes['+'] = 62;          codes['/'] = 63;      }         private static byte[] readBytes(File file) throws IOException {          ByteArrayOutputStream baos = new ByteArrayOutputStream();          byte[] b = null;          InputStream fis = null;          InputStream is = null;          try {              fis = new FileInputStream(file);              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);                  }              }              b = baos.toByteArray();             } finally {              try {                  if (fis != null)                      fis.close();                  if (is != null)                      is.close();                  if (baos != null)                      baos.close();              } catch (Exception e) {                  System.out.println(e);              }          }             return b;      }         private static char[] readChars(File file) throws IOException {          CharArrayWriter caw = new CharArrayWriter();          Reader fr = null;          Reader in = null;          try {              fr = new FileReader(file);              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);                  }              }             } finally {              try {                  if (caw != null)                      caw.close();                  if (in != null)                      in.close();                  if (fr != null)                      fr.close();              } catch (Exception e) {                  System.out.println(e);              }          }             return caw.toCharArray();      }         private static void writeBytes(File file, byte[] data) throws IOException {          OutputStream fos = null;          OutputStream os = null;          try {              fos = new FileOutputStream(file);              os = new BufferedOutputStream(fos);              os.write(data);             } finally {              try {                  if (os != null)                      os.close();                  if (fos != null)                      fos.close();              } catch (Exception e) {                  System.out.println(e);              }          }      }         private static void writeChars(File file, char[] data) throws IOException {          Writer fos = null;          Writer os = null;          try {              fos = new FileWriter(file);              os = new BufferedWriter(fos);              os.write(data);             } finally {              try {                  if (os != null)                      os.close();                  if (fos != null)                      fos.close();              } catch (Exception e) {                  e.printStackTrace();              }          }      }     }