Java Base64位编码与String字符串的相互转换,Base64与Bitmap的相互转换实例代码

首先是网上大神给的类

package com.duanlian.daimengmusic.utils;
public final class base64util {
  private static final int baselength = 128;
  private static final int lookuplength = 64;
  private static final int twentyfourbitgroup = 24;
  private static final int eightbit = 8;
  private static final int sixteenbit = 16;
  private static final int fourbyte = 4;
  private static final int sign = -128;
  private static char pad = '=';
  private static byte[] base64alphabet = new byte[baselength];
  private static char[] lookupbase64alphabet = new char[lookuplength];
  static {
    for (int i = 0; i < baselength; ++i) {
      base64alphabet[i] = -1;
    }
    for (int i = 'z'; i >= 'a'; i--) {
      base64alphabet[i] = (byte) (i - 'a');
    }
    for (int i = 'z'; i >= 'a'; i--) {
      base64alphabet[i] = (byte) (i - 'a' + 26);
    }
    for (int i = '9'; i >= '0'; i--) {
      base64alphabet[i] = (byte) (i - '0' + 52);
    }
    base64alphabet['+'] = 62;
    base64alphabet['/'] = 63;
    for (int i = 0; i <= 25; i++) {
      lookupbase64alphabet[i] = (char) ('a' + i);
    }
    for (int i = 26, j = 0; i <= 51; i++, j++) {
      lookupbase64alphabet[i] = (char) ('a' + j);
    }
    for (int i = 52, j = 0; i <= 61; i++, j++) {
      lookupbase64alphabet[i] = (char) ('0' + j);
    }
    lookupbase64alphabet[62] = (char) '+';
    lookupbase64alphabet[63] = (char) '/';
  }
  private static boolean iswhitespace(char octect) {
    return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
  }
  private static boolean ispad(char octect) {
    return (octect == pad);
  }
  private static boolean isdata(char octect) {
    return (octect < baselength && base64alphabet[octect] != -1);
  }
  /**
   把64位byte数组转换成string
   */
  public static string encode(byte[] binarydata) {
    if (binarydata == null) {
      return null;
    }
    int lengthdatabits = binarydata.length * eightbit;
    if (lengthdatabits == 0) {
      return "";
    }
    int fewerthan24bits = lengthdatabits % twentyfourbitgroup;
    int numbertriplets = lengthdatabits / twentyfourbitgroup;
    int numberquartet = fewerthan24bits != 0 ? numbertriplets + 1
        : numbertriplets;
    char encodeddata[] = null;
    encodeddata = new char[numberquartet * 4];
    byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
    int encodedindex = 0;
    int dataindex = 0;
    for (int i = 0; i < numbertriplets; i++) {
      b1 = binarydata[dataindex++];
      b2 = binarydata[dataindex++];
      b3 = binarydata[dataindex++];
      l = (byte) (b2 & 0x0f);
      k = (byte) (b1 & 0x03);
      byte val1 = ((b1 & sign) == 0) ? (byte) (b1 >> 2)
          : (byte) ((b1) >> 2 ^ 0xc0);
      byte val2 = ((b2 & sign) == 0) ? (byte) (b2 >> 4)
          : (byte) ((b2) >> 4 ^ 0xf0);
      byte val3 = ((b3 & sign) == 0) ? (byte) (b3 >> 6)
          : (byte) ((b3) >> 6 ^ 0xfc);
      encodeddata[encodedindex++] = lookupbase64alphabet[val1];
      encodeddata[encodedindex++] = lookupbase64alphabet[val2 | (k << 4)];
      encodeddata[encodedindex++] = lookupbase64alphabet[(l << 2) | val3];
      encodeddata[encodedindex++] = lookupbase64alphabet[b3 & 0x3f];
    }
    // form integral number of 6-bit groups
    if (fewerthan24bits == eightbit) {
      b1 = binarydata[dataindex];
      k = (byte) (b1 & 0x03);
      byte val1 = ((b1 & sign) == 0) ? (byte) (b1 >> 2)
          : (byte) ((b1) >> 2 ^ 0xc0);
      encodeddata[encodedindex++] = lookupbase64alphabet[val1];
      encodeddata[encodedindex++] = lookupbase64alphabet[k << 4];
      encodeddata[encodedindex++] = pad;
      encodeddata[encodedindex++] = pad;
    } else if (fewerthan24bits == sixteenbit) {
      b1 = binarydata[dataindex];
      b2 = binarydata[dataindex + 1];
      l = (byte) (b2 & 0x0f);
      k = (byte) (b1 & 0x03);
      byte val1 = ((b1 & sign) == 0) ? (byte) (b1 >> 2)
          : (byte) ((b1) >> 2 ^ 0xc0);
      byte val2 = ((b2 & sign) == 0) ? (byte) (b2 >> 4)
          : (byte) ((b2) >> 4 ^ 0xf0);
      encodeddata[encodedindex++] = lookupbase64alphabet[val1];
      encodeddata[encodedindex++] = lookupbase64alphabet[val2 | (k << 4)];
      encodeddata[encodedindex++] = lookupbase64alphabet[l << 2];
      encodeddata[encodedindex++] = pad;
    }
    return new string(encodeddata);
  }
  /**
   * 把base64位编码转换成byte数组
   */
  public static byte[] decode(string encoded) {
    if (encoded == null) {
      return null;
    }
    char[] base64data = encoded.tochararray();
    // remove white spaces
    int len = removewhitespace(base64data);
    if (len % fourbyte != 0) {
      return null;// should be divisible by four
    }
    int numberquadruple = (len / fourbyte);
    if (numberquadruple == 0) {
      return new byte[0];
    }
    byte decodeddata[] = null;
    byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
    char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
    int i = 0;
    int encodedindex = 0;
    int dataindex = 0;
    decodeddata = new byte[(numberquadruple) * 3];
    for (; i < numberquadruple - 1; i++) {
      if (!isdata((d1 = base64data[dataindex++]))
          || !isdata((d2 = base64data[dataindex++]))
          || !isdata((d3 = base64data[dataindex++]))
          || !isdata((d4 = base64data[dataindex++]))) {
        return null;
      }// if found "no data" just return null
      b1 = base64alphabet[d1];
      b2 = base64alphabet[d2];
      b3 = base64alphabet[d3];
      b4 = base64alphabet[d4];
      decodeddata[encodedindex++] = (byte) (b1 << 2 | b2 >> 4);
      decodeddata[encodedindex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
      decodeddata[encodedindex++] = (byte) (b3 << 6 | b4);
    }
    if (!isdata((d1 = base64data[dataindex++]))
        || !isdata((d2 = base64data[dataindex++]))) {
      return null;// if found "no data" just return null
    }
    b1 = base64alphabet[d1];
    b2 = base64alphabet[d2];
    d3 = base64data[dataindex++];
    d4 = base64data[dataindex++];
    if (!isdata((d3)) || !isdata((d4))) {// check if they are pad characters
      if (ispad(d3) && ispad(d4)) {
        if ((b2 & 0xf) != 0)// last 4 bits should be zero
        {
          return null;
        }
        byte[] tmp = new byte[i * 3 + 1];
        system.arraycopy(decodeddata, 0, tmp, 0, i * 3);
        tmp[encodedindex] = (byte) (b1 << 2 | b2 >> 4);
        return tmp;
      } else if (!ispad(d3) && ispad(d4)) {
        b3 = base64alphabet[d3];
        if ((b3 & 0x3) != 0)// last 2 bits should be zero
        {
          return null;
        }
        byte[] tmp = new byte[i * 3 + 2];
        system.arraycopy(decodeddata, 0, tmp, 0, i * 3);
        tmp[encodedindex++] = (byte) (b1 << 2 | b2 >> 4);
        tmp[encodedindex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
        return tmp;
      } else {
        return null;
      }
    } else { // no pad e.g 3cql
      b3 = base64alphabet[d3];
      b4 = base64alphabet[d4];
      decodeddata[encodedindex++] = (byte) (b1 << 2 | b2 >> 4);
      decodeddata[encodedindex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
      decodeddata[encodedindex++] = (byte) (b3 << 6 | b4);
    }
    return decodeddata;
  }
  /**
   * remove whitespace from mime containing encoded base64util data.
   * 
   * @param data
   *      the byte array of base64 data (with ws)
   * @return the new length
   */
  private static int removewhitespace(char[] data) {
    if (data == null) {
      return 0;
    }
    // count characters that's not whitespace
    int newsize = 0;
    int len = data.length;
    for (int i = 0; i < len; i++) {
      if (!iswhitespace(data[i])) {
        data[newsize++] = data[i];
      }
    }
    return newsize;
  }
}

然后是我经过2次封装的类,注释很清楚,拿过去直接用就行

package com.duanlian.daimengmusic.utils;
import android.graphics.bitmap;
import android.graphics.bitmapfactory;
import android.util.base64;
import java.io.bytearrayoutputstream;
import java.io.ioexception;
/**
 * 转换编码
 */
public class base64object {
  /**
   * 把base64的string码转换成正常显示的字符串
   */
  public static string base64tostring(string base64) {
    byte[] decode = base64util.decode(base64);
    string s = new string(decode);
    return s;
  }
  /**
   * 把string的转换成base64码
   */
  public static string stringtobase64(string ss) {
    byte[] bytes = ss.getbytes();
    string encode = base64util.encode(bytes);
    return encode;
  }
  /**
   * bitmap转为base64
   * @param bitmap
   * @return
   */
  public static string bitmaptobase641(bitmap bitmap) {
    string result = null;
    bytearrayoutputstream baos = null;
    try {
      if (bitmap != null) {
        baos = new bytearrayoutputstream();
        bitmap.compress(bitmap.compressformat.jpeg, 100, baos);
        baos.flush();
        baos.close();
        byte[] bitmapbytes = baos.tobytearray();
        result = base64.encodetostring(bitmapbytes, base64.default);
      }
    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      try {
        if (baos != null) {
          baos.flush();
          baos.close();
        }
      } catch (ioexception e) {
        e.printstacktrace();
      }
    }
    return result;
  }
  /**
   * base64转为bitmap
   * @param base64data
   * @return
   */
  public static bitmap base64tobitmap(string base64data) {
    byte[] bytes = base64.decode(base64data, base64.default);
    return bitmapfactory.decodebytearray(bytes, 0, bytes.length);
  }
}

以上所述是小编给大家介绍的java base64位编码与string字符串的相互转换,base64与bitmap的相互转换实例代码，希望对大家有所帮助