[置顶] Java、Android、IOS通用的加密解密方法

package com.changyou.ims.mobile.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
* Base64编码工具类
*/
public class CustomBase64 {
   private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-".toCharArray();

   public static String encode(byte[] data) {
       int start = 0;
       int len = data.length;
       StringBuffer buf = new StringBuffer(data.length * 3 / 2);

       int end = len - 3;
       int i = start;
       int n = 0;

       while (i <= end) {
           int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff);

           buf.append(legalChars[(d >> 18) & 63]);
           buf.append(legalChars[(d >> 12) & 63]);
           buf.append(legalChars[(d >> 6) & 63]);
           buf.append(legalChars[d & 63]);

           i += 3;

           if (n++ >= 14) {
               n = 0;
               buf.append("");
           }
       }

       if (i == start + len - 2) {
           int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);

           buf.append(legalChars[(d >> 18) & 63]);
           buf.append(legalChars[(d >> 12) & 63]);
           buf.append(legalChars[(d >> 6) & 63]);
           buf.append("=");
       } else if (i == start + len - 1) {
           int d = (((int) data[i]) & 0x0ff) << 16;

           buf.append(legalChars[(d >> 18) & 63]);
           buf.append(legalChars[(d >> 12) & 63]);
           buf.append("==");
       }

       return buf.toString();
   }

   private static int decode(char c) {
       if (c >= 'A' && c <= 'Z')
           return ((int) c) - 65;
       else if (c >= 'a' && c <= 'z')
           return ((int) c) - 97 + 26;
       else if (c >= '0' && c <= '9')
           return ((int) c) - 48 + 26 + 26;
       else
           switch (c) {
           case '+':
               return 62;
           case '-':
               return 63;
           case '=':
               return 0;
           default:
               throw new RuntimeException("unexpected code: " + c);
           }
   }

   /**
  * Decodes the given Base64 encoded String to a new byte array. The byte array holding the decoded data is returned.
  */

   public static byte[] decode(String s) {

       ByteArrayOutputStream bos = new ByteArrayOutputStream();
       try {
           decode(s, bos);
       } catch (IOException e) {
           throw new RuntimeException();
       }
       byte[] decodedBytes = bos.toByteArray();
       try {
           bos.close();
           bos = null;
       } catch (IOException ex) {
           System.err.println("Error while decoding BASE64: " + ex.toString());
       }
       return decodedBytes;
   }

   private static void decode(String s, OutputStream os) throws IOException {
       int i = 0;

       int len = s.length();

       while (true) {
           while (i < len && s.charAt(i) <= ' ')
               i++;

           if (i == len)
               break;

           int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3)));

           os.write((tri >> 16) & 255);
           if (s.charAt(i + 2) == '=')
               break;
           os.write((tri >> 8) & 255);
           if (s.charAt(i + 3) == '=')
               break;
           os.write(tri & 255);

           i += 4;
       }
   }
}

首先感谢网友的分享，原帖地址：

http://www.eoeandroid.com/thread-237997-1-1.html

拿到自己项目里本来挺好用的，但是在安卓客户端和服务器端通信的时候出错了，看了下原因，是因为加密后的字符串里有“/”和空格，本来想放弃这个方法来着，或者取巧一下把这两个字符替换掉，后来想想还是想追查下原因，结果在原作者自己定义的base64类里看到了端倪，稍作修改后，没有问题了！

这里就不附加密解密的方法了，大家如果需要可以去上面的链接看，我只把修改后的base64类发一下吧！