我有一个binhex文件。应使用java代码将此文件转换为普通可读文件。 我在这里找到了类似的问题，
Binhex decoding using java code
但答案是行不通的。
我尝试过Base64，该文件被转换为其他一些人类不可读的格式。
请帮我解决此问题。
我尝试的代码如下
File f = new File("Sample.pdf");
Base64 base64 = new Base64();
byte[] b = base64.decode(getBytesFromFile(f));
FileOutputStream fos = new FileOutputStream("Dcode.pdf");
fos.write(b);
fos.close();
public static byte[] getBytesFromFile(File file) throws IOException {
InputStream is = new FileInputStream(file);
long length = file.length();
byte[] bytes = new byte[(int)length];
int offset = 0;
int numRead = 0;
while (offset < bytes.length && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0)
{
offset += numRead;
}
if (offset < bytes.length) {
throw new IOException("Could not completely read file "+file.getName());
}
is.close();
return bytes;
}
文件Sample.pdf是BinHex ecoded。我想要解码文件。
答案 0 :(得分：3)
根据我在网上找到的，有BinHex格式的不同版本。它们都不是Base64完全相同的。然而，有很多相似之处。以BinHex 4.0 specs为例，我们看到主要的二进制内容是使用带有base 64的编码方案编码的，因此将3个八位字节编码为4个字符。但它使用不同的字母表：
BinHex: !"#$%&'()*+,-012345689@ABCDEFGHIJKLMNPQRSTUVXYZ[`abcdefhijklmpqr
Base64: ABCDEFGHIJKLMNOPQERTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
所以你要么必须从一组字符转换到另一组字符，要么自己做解码。
除了大量的二进制内容外，格式中还包含一些额外的元数据。根据规范，它包括数据和资源分支内容，校验和以及其他一些信息之间的分隔符。
以下代码将解码BinHex输入文件并将其数据分支写入输出文件。根据您的需要调整此代码应该很容易。
import java.io.*;
import java.nio.charset.Charset;
public class BinHexDec {
private Charset charset;
private String filename;
private int dbegin, dend, rbegin, rend;
public BinHexDec(String... args) throws IOException {
InputStream in = System.in;
OutputStream out = System.out;
charset = Charset.defaultCharset();
if (args.length >= 1)
in = new FileInputStream(args[0]);
if (args.length >= 2)
out = new FileOutputStream(args[1]);
if (args.length >= 3)
charset = Charset.forName(args[2]);
Reader reader = new InputStreamReader(in, charset);
byte[] data;
data = unbase(reader);
reader.close();
if (data.length < 27)
throw new IOException("Too little data");
data = unrle(data);
parse(data);
out.write(data, dbegin, dend - dbegin);
}
private byte[] unbase(Reader in) throws IOException {
String digits = "!\"#$%&'()*+,-012345689@ABCDEFGHIJKLMNPQRSTUVXYZ" +
"[`abcdefhijklmpqr";
assert digits.length() == (1 << 6);
int[] value = new int[128];
for (int i = 0; i < value.length; ++i)
value[i] = -1;
for (int i = 0; i < digits.length(); ++i)
value[digits.charAt(i)] = i;
int state = 0;
int accum = 0;
int alen = 0;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
while (true) {
int chr = in.read();
if (chr == -1)
throw new EOFException();
switch (state) {
case 0:
switch (chr) {
case '\n':
case '\r':
case '\t':
case ' ':
state = 1;
break;
}
break;
case 1:
switch (chr) {
case '\n':
case '\r':
case '\t':
case ' ':
break;
case ':':
state = 2;
break;
default:
state = 0;
}
break;
case 2:
int v = -1, c = chr & 0x7f;
if (c == chr) {
v = value[c];
if (v != -1) {
accum = (accum << 6) | v;
alen += 6;
if (alen > 8) {
alen -= 8;
baos.write((byte)(accum >>> alen));
}
break;
}
}
if (chr == ':') {
return baos.toByteArray();
}
break;
}
}
}
private static final byte RLE_MARK = (byte)0x90;
private byte[] unrle(byte[] in) throws IOException {
int len = in.length;
if (in[0] == 0x90)
throw new IOException("Incomplete RLE at beginning");
for (int i = 0; i < in.length; ++i) {
if (in[i] == RLE_MARK) {
++i;
if (i == in.length)
throw new IOException("Incomplete RLE at end");
int cnt = in[i] & 0xff;
if (cnt == 0)
len -= 1;
else
len += cnt - 3;
}
}
byte[] out = new byte[len];
for (int i = 0, o = 0; i < in.length; ++i) {
if (in[i] == RLE_MARK) {
++i;
int cnt = in[i] & 0xff;
if (cnt == 0)
out[o++] = RLE_MARK;
else {
byte b = out[o - 1];
for (int c = 1; c < cnt; ++c)
out[o++] = b;
}
}
else {
out[o++] = in[i];
}
}
return out;
}
private int get4(byte[] data, int offset) {
return ((data[offset ] & 0xff) << 24)
| ((data[offset + 1] & 0xff) << 16)
| ((data[offset + 2] & 0xff) << 8)
| ((data[offset + 3] & 0xff) );
}
private int get2(byte[] data, int offset) {
return ((data[offset] & 0xff) << 8)
| ((data[offset + 1] & 0xff));
}
private void crcCheck(byte[] data, int begin, int end) throws IOException {
int crc = 0;
for (int i = begin; i < end; ++i) {
crc = ((crc << 4)&0xffff) ^ (crc >> 12)*0x1021;
crc = ((crc << 4)&0xffff) ^ (crc >> 12)*0x1021;
crc = crc ^ (data[i] & 0xff);
}
crc = ((crc << 4)&0xffff) ^ (crc >> 12)*0x1021;
crc = ((crc << 4)&0xffff) ^ (crc >> 12)*0x1021;
crc = ((crc << 4)&0xffff) ^ (crc >> 12)*0x1021;
crc = ((crc << 4)&0xffff) ^ (crc >> 12)*0x1021;
int expected = get2(data, end);
if (expected != crc)
throw new IOException("CRC mismatch");
}
private void parse(byte[] in) throws IOException {
int namelen = in[0] & 0xff;
int headlen = namelen + 20;
int dlen = get4(in, headlen - 8);
int rlen = get4(in, headlen - 4);
if (dlen < 0 || rlen < 0)
throw new IOException("Unsigned data lenhgths not supported");
dbegin = headlen + 2;
dend = dbegin + dlen;
rbegin = dend + 2;
rend = rbegin + rlen;
if (in.length != rend + 2 &&
(in.length != rend + 3 || in[rend + 2] != 0))
throw new IOException("Incorrect data size:" +
" expected " + (rend + 2) +
" but got " + in.length + " bytes");
crcCheck(in, 0, headlen);
crcCheck(in, dbegin, dend);
crcCheck(in, rbegin, rend);
filename = new String(in, 1, namelen, charset);
System.err.println(filename);
}
public static void main(String[] args) throws IOException {
new BinHexDec(args);
}
}