在C中解码Java Base64字符串？

Question

如何解码C中的字符串，在Java中编码为Base64？ 我有字符串，在Java中编码为Base64。 现在我需要在C中解码这个字符串。我该怎么做？

我在C中使用了一些Base64库，但结果是一样的。 解码数据与Java中的原始数据不同。 当我使用可读的ASCII字符作为输入数据时，它会起作用，但我需要-127 +128范围内的所有数据。

我的编码数据的的短样品 “flBJQ1RVUkV8AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAAA / wAAAP8AAAD / AAA“ < / p>

这是我用于解码Base64的代码的一部分：

// Make sure we have enough space to add '\0' character at end.
      dec = (unsigned char *) b64_realloc(dec, size + 1);
      if (dec != NULL){
        dec[size] = '\0';
      } else {
        return NULL;
      }

      // Return back the size of decoded string if demanded.
      if (decsize != NULL) {
        *decsize = size;
      }

      return dec;
    }

    unsigned char *b64_decode_ex3 (const char *src, size_t len, size_t *decsize) {
      int i = 0;
      int j = 0;
      int l = 0;
      size_t size = 0;
      unsigned char *dec = NULL;
      unsigned char buf[3];
      unsigned char tmp[4];

      // alloc
      dec = (unsigned char *) b64_malloc(1);
      if (NULL == dec) { return NULL; }

      // parse until end of source
      while (len--) {
        // break if char is `=' or not base64 char
        if ('=' == src[j]) { break; }
        //if (!(isalnum(src[j]) || '+' == src[j] || '/' == src[j])) { break; }

        // read up to 4 bytes at a time into `tmp'
        tmp[i++] = src[j++];

        // if 4 bytes read then decode into `buf'
        if (4 == i) {
          // translate values in `tmp' from table
          for (i = 0; i < 4; ++i) {
            // find translation char in `b64_table'
            for (l = 0; l < 64; ++l) {
              if (tmp[i] == b64_table[l]) {
                tmp[i] = l;
                break;
              }
            }
          }

          // decode
          buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
          buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
          buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];

          // write decoded buffer to `dec'
          dec = (unsigned char *) b64_realloc(dec, size + 3);
          if (dec != NULL){
            for (i = 0; i < 3; ++i) {
              dec[size++] = buf[i];
            }
          } else {
            return NULL;
          }

          // reset
          i = 0;
        }
      }

      // remainder
      if (i > 0) {
        // fill `tmp' with `\0' at most 4 times
        for (j = i; j < 4; ++j) {
          tmp[j] = '\0';
        }

        // translate remainder
        for (j = 0; j < 4; ++j) {
            // find translation char in `b64_table'
            for (l = 0; l < 64; ++l) {
              if (tmp[j] == b64_table[l]) {
                tmp[j] = l;
                break;
              }
            }
        }

        // decode remainder
        buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
        buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
        buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];

        // write remainer decoded buffer to `dec'
        dec = (unsigned char *) b64_realloc(dec, size + (i - 1));
        if (dec != NULL){
          for (j = 0; (j < i - 1); ++j) {
            dec[size++] = buf[j];
          }
        } else {
          return NULL;
        }
      }

      // Make sure we have enough space to add '\0' character at end.
      dec = (unsigned char *) b64_realloc(dec, size + 1);
      if (dec != NULL){
        dec[size] = '\0';
      } else {
        return NULL;
      }

      // Return back the size of decoded string if demanded.
      if (decsize != NULL) {
        *decsize = size;
      }

      return dec;
    }