base64.java

来自「对于cmpp3.0 开发有一定的帮助,请大家下载下来进行研究.」· Java 代码 · 共 65 行

package com.zhanghao.common.util;

public class Base64 {

  public Base64() {
  }


  public static String decodeBase64(String data) {
      return decodeBase64(data.getBytes());
    }

    /**
     * Decodes a base64 aray of bytes.
     *
     * @param data a base64 encode byte array to decode.
     * @return the decoded String.
     */

  private static  String decodeBase64(byte[] data) {
      int fillchar = '=';
      String cvt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        + "abcdefghijklmnopqrstuvwxyz"
        + "0123456789+/";

      int c, c1;
      int len = data.length;
      StringBuffer ret = new StringBuffer( (len * 3) / 4);
      for (int i = 0; i < len; ++i) {
        c = cvt.indexOf(data[i]);
        ++i;
        c1 = cvt.indexOf(data[i]);
        c = ( (c << 2) | ( (c1 >> 4) & 0x3));
        ret.append( (char) c);
        if (++i < len) {
          c = data[i];
          if (fillchar == c)
            break;

          c = cvt.indexOf( (char) c);
          c1 = ( (c1 << 4) & 0xf0) | ( (c >> 2) & 0xf);
          ret.append( (char) c1);
        }

        if (++i < len) {
          c1 = data[i];
          if (fillchar == c1)
            break;

          c1 = cvt.indexOf( (char) c1);
          c = ( (c << 6) & 0xc0) | c1;
          ret.append( (char) c);
        }
      }
      return ret.toString();


    }

    public static void main(String args[]){
      String s= "JERHIEZZWEVRICAwNzMxNTc0MjU3NTplcWEkMTEwJC0xJCQkMCQwJDkxMTI3JDAkMTAyMDEzMzEzNDAyMDAwMjIwNjEkNjQkUmVnaXN0aW5nJDIwMDYtMTAtMjAgMTM6Mzc6MzE6MTA1JDEzJDAkMjAwNi0xMC0yMCAxMzozNzozMSQkJCQwNzMxNTc0MjU3NSQ=";
      System.out.println(decodeBase64(s));
    }
}