文件请求应始终带有 MD5 校验和。如果您有 MD5 标头,那么您需要做的就是对照生成的 MD5 文件检查它。然后你完成了,最好这样做,因为你可以拥有一个具有相同字节数的文件,但一个字节在传输中会出现乱码。
entity.writeTo(new FileOutputStream(outfile));
String md5 = response.getHeaders("Content-MD5")[0].getValue();
byte[] b64 = Base64.decode(md5, Base64.DEFAULT);
String sB64 = IntegrityUtils.toASCII(b64, 0, b64.length);
if (outfile.exists()) {
String orgMd5 = null;
try {
orgMd5 = IntegrityUtils.getMD5Checksum(outfile);
} catch (Exception e) {
Log.d(TAG,"Exception in file hex...");
}
if (orgMd5 != null && orgMd5.equals(sB64)) {
Log.d(TAG,"MD5 is equal to files MD5");
} else {
Log.d(TAG,"MD5 does not equal files MD5");
}
}
将此类添加到您的项目中:
public class IntegrityUtils {
public static String toASCII(byte b[], int start, int length) {
StringBuffer asciiString = new StringBuffer();
for (int i = start; i < (length + start); i++) {
// exclude nulls from the ASCII representation
if (b[i] != (byte) 0x00) {
asciiString.append((char) b[i]);
}
}
return asciiString.toString();
}
public static String getMD5Checksum(File file) throws Exception {
byte[] b = createChecksum(file);
String result = "";
for (int i = 0; i < b.length; i++) {
result += Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1);
}
return result;
}
public static byte[] createChecksum(File file) throws Exception {
InputStream fis = new FileInputStream(file);
byte[] buffer = new byte[1024];
MessageDigest complete = MessageDigest.getInstance("MD5");
int numRead;
do {
numRead = fis.read(buffer);
if (numRead > 0) {
complete.update(buffer, 0, numRead);
}
} while (numRead != -1);
fis.close();
return complete.digest();
}
}