我想使用Java来获得文件的MD5校验和。我真的很惊讶,但我还没有找到任何东西,显示如何获得一个文件的MD5校验和。
这是怎么做到的?
我想使用Java来获得文件的MD5校验和。我真的很惊讶,但我还没有找到任何东西,显示如何获得一个文件的MD5校验和。
这是怎么做到的?
当前回答
下面是一个方便的变体,它利用了Java 9中的InputStream.transferTo()和Java 11中的OutputStream.nullOutputStream()。它不需要外部库,也不需要将整个文件加载到内存中。
public static String hashFile(String algorithm, File f) throws IOException, NoSuchAlgorithmException {
MessageDigest md = MessageDigest.getInstance(algorithm);
try(BufferedInputStream in = new BufferedInputStream((new FileInputStream(f)));
DigestOutputStream out = new DigestOutputStream(OutputStream.nullOutputStream(), md)) {
in.transferTo(out);
}
String fx = "%0" + (md.getDigestLength()*2) + "x";
return String.format(fx, new BigInteger(1, md.digest()));
}
and
hashFile("SHA-512", Path.of("src", "test", "resources", "some.txt").toFile());
返回
"e30fa2784ba15be37833d569280e2163c6f106506dfb9b07dde67a24bfb90da65c661110cf2c5c6f71185754ee5ae3fd83a5465c92f72abd888b03187229da29"
其他回答
public static String getMd5OfFile(String filePath)
{
String returnVal = "";
try
{
InputStream input = new FileInputStream(filePath);
byte[] buffer = new byte[1024];
MessageDigest md5Hash = MessageDigest.getInstance("MD5");
int numRead = 0;
while (numRead != -1)
{
numRead = input.read(buffer);
if (numRead > 0)
{
md5Hash.update(buffer, 0, numRead);
}
}
input.close();
byte [] md5Bytes = md5Hash.digest();
for (int i=0; i < md5Bytes.length; i++)
{
returnVal += Integer.toString( ( md5Bytes[i] & 0xff ) + 0x100, 16).substring( 1 );
}
}
catch(Throwable t) {t.printStackTrace();}
return returnVal.toUpperCase();
}
下面是一个方便的变体,它利用了Java 9中的InputStream.transferTo()和Java 11中的OutputStream.nullOutputStream()。它不需要外部库,也不需要将整个文件加载到内存中。
public static String hashFile(String algorithm, File f) throws IOException, NoSuchAlgorithmException {
MessageDigest md = MessageDigest.getInstance(algorithm);
try(BufferedInputStream in = new BufferedInputStream((new FileInputStream(f)));
DigestOutputStream out = new DigestOutputStream(OutputStream.nullOutputStream(), md)) {
in.transferTo(out);
}
String fx = "%0" + (md.getDigestLength()*2) + "x";
return String.format(fx, new BigInteger(1, md.digest()));
}
and
hashFile("SHA-512", Path.of("src", "test", "resources", "some.txt").toFile());
返回
"e30fa2784ba15be37833d569280e2163c6f106506dfb9b07dde67a24bfb90da65c661110cf2c5c6f71185754ee5ae3fd83a5465c92f72abd888b03187229da29"
public static void main(String[] args) throws Exception {
MessageDigest md = MessageDigest.getInstance("MD5");
FileInputStream fis = new FileInputStream("c:\\apache\\cxf.jar");
byte[] dataBytes = new byte[1024];
int nread = 0;
while ((nread = fis.read(dataBytes)) != -1) {
md.update(dataBytes, 0, nread);
};
byte[] mdbytes = md.digest();
StringBuffer sb = new StringBuffer();
for (int i = 0; i < mdbytes.length; i++) {
sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
}
System.out.println("Digest(in hex format):: " + sb.toString());
}
或者你可以得到更多的信息 http://www.asjava.com/core-java/java-md5-example/
使用Apache Commons Codec库中的DigestUtils:
try (InputStream is = Files.newInputStream(Paths.get("file.zip"))) {
String md5 = org.apache.commons.codec.digest.DigestUtils.md5Hex(is);
}
String checksum = DigestUtils.md5Hex(new FileInputStream(filePath));