Getting a File s MD5 Checksum in Java

Question

I am looking to use Java to get the MD5 checksum of a file   I was really surprised but I haven t been able to find anything that shows how to get the MD5 checksum of a file   How is it done

User · Answer

I recently had to do this for just a dynamic string, MessageDigest can represent the hash in numerous ways. To get the signature of the file like you would get with the md5sum command I had to do something like the this:

try {
   String s = "TEST STRING";
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   md5.update(s.getBytes(),0,s.length());
   String signature = new BigInteger(1,md5.digest()).toString(16);
   System.out.println("Signature: "+signature);

} catch (final NoSuchAlgorithmException e) {
   e.printStackTrace();
}

This obviously doesn't answer your question about how to do it specifically for a file, the above answer deals with that quiet nicely. I just spent a lot of time getting the sum to look like most application's display it, and thought you might run into the same trouble.

User · Answer

If you re using ANT to build  this is dead-simple   Add the following to your build xml    lt checksum file    jarFile   todir    toDir    gt    Where jarFile is the JAR you want to generate the MD5 against  and toDir is the directory you want to place the MD5 file   More info here

User · Answer

Ok  I had to add  One line implementation for those who already have Spring and Apache Commons dependency or are planning to add it   DigestUtils md5DigestAsHex FileUtils readFileToByteArray file     For and Apache commons only option  credit  duleshi    DigestUtils md5Hex FileUtils readFileToByteArray file     Hope this helps someone

User · Answer

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  lt  mdbytes length  i              sb append Integer toString  mdbytes i   amp  0xff    0x100  16  substring 1              System out println  Digest in hex format        sb toString         Or you may get more info  http   www asjava com core-java java-md5-example

User · Answer

String checksum   DigestUtils md5Hex new FileInputStream filePath

User · Answer

The com google common hash API offers    A unified user-friendly API for all hash functions Seedable 32- and 128-bit implementations of murmur3 md5    sha1    sha256    sha512   adapters  change only one line of code to switch between these  and murmur  goodFastHash int bits   for when you don t care what algorithm you use General utilities for HashCode instances  like combineOrdered   combineUnordered   Read the User Guide  IO Explained  Hashing Explained     For your use-case Files hash   computes and returns the digest value for a file   For example a sha-1 digest calculation  change SHA-1 to MD5 to get MD5 digest   HashCode hc   Files asByteSource file  hash Hashing sha1      SHA-1      hc toString      Note that crc32 is much faster than md5  so use crc32 if you do not need a cryptographically secure checksum  Note also that md5 should not be used to store passwords and the like since it is to easy to brute force  for passwords use bcrypt   scrypt or sha-256 instead    For long term protection with hashes a  Merkle signature scheme adds to the security and The Post Quantum Cryptography Study Group sponsored by the European Commission has recommended use of this cryptography for long term protection against quantum computers  ref    Note that crc32 has a higher collision rate than the others

User · Answer

I recently had to do this for just a dynamic string, MessageDigest can represent the hash in numerous ways. To get the signature of the file like you would get with the md5sum command I had to do something like the this:

try {
   String s = "TEST STRING";
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   md5.update(s.getBytes(),0,s.length());
   String signature = new BigInteger(1,md5.digest()).toString(16);
   System.out.println("Signature: "+signature);

} catch (final NoSuchAlgorithmException e) {
   e.printStackTrace();
}

This obviously doesn't answer your question about how to do it specifically for a file, the above answer deals with that quiet nicely. I just spent a lot of time getting the sum to look like most application's display it, and thought you might run into the same trouble.

User · Answer

I recently had to do this for just a dynamic string, MessageDigest can represent the hash in numerous ways. To get the signature of the file like you would get with the md5sum command I had to do something like the this:

try {
   String s = "TEST STRING";
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   md5.update(s.getBytes(),0,s.length());
   String signature = new BigInteger(1,md5.digest()).toString(16);
   System.out.println("Signature: "+signature);

} catch (final NoSuchAlgorithmException e) {
   e.printStackTrace();
}

This obviously doesn't answer your question about how to do it specifically for a file, the above answer deals with that quiet nicely. I just spent a lot of time getting the sum to look like most application's display it, and thought you might run into the same trouble.

User · Answer

Here is a handy variation that makes use of InputStream transferTo   from Java 9  and OutputStream nullOutputStream   from Java 11  It requires no external libraries and does not need to load the entire file into memory   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       returns    e30fa2784ba15be37833d569280e2163c6f106506dfb9b07dde67a24bfb90da65c661110cf2c5c6f71185754ee5ae3fd83a5465c92f72abd888b03187229da29

User · Answer

There s an example at Real s Java-How-to using the MessageDigest class   Check that page for examples using CRC32 and SHA-1 as well   import java io    import java security MessageDigest   public class MD5Checksum       public static byte   createChecksum String filename  throws Exception          InputStream fis    new FileInputStream filename           byte   buffer   new byte 1024          MessageDigest complete   MessageDigest getInstance  MD5           int numRead          do              numRead   fis read buffer              if  numRead  gt  0                   complete update buffer  0  numRead                         while  numRead    -1           fis close           return complete digest                see this How-to for a faster way to convert       a byte array to a HEX string    public static String getMD5Checksum String filename  throws Exception          byte   b   createChecksum filename          String result               for  int i 0  i  lt  b length  i                 result    Integer toString    b i   amp  0xff     0x100  16  substring  1                    return result           public static void main String args             try              System out println getMD5Checksum  apache-tomcat-5 5 17 exe                   output                  0bb2827c5eacf570b6064e24e0e6653b               ref                  http   www apache org dist                         tomcat tomcat-5 v5 5 17 bin                             apache-tomcat-5 5 17 exe MD5                0bb2827c5eacf570b6064e24e0e6653b  apache-tomcat-5 5 17 exe                 catch  Exception e               e printStackTrace

User · Answer

public static String MD5Hash String toHash  throws RuntimeException      try         return String format   032x      produces lower case 32 char wide hexa left-padded with 0       new BigInteger 1     handles large POSITIVE numbers             MessageDigest getInstance  MD5   digest toHash getBytes               catch  NoSuchAlgorithmException e             do whatever seems relevant

User · Answer

Guava now provides a new  consistent hashing API that is much more user-friendly than the various hashing APIs provided in the JDK  See Hashing Explained  For a file  you can get the MD5 sum  CRC32  with version 14 0   or many other hashes easily   HashCode md5   Files hash file  Hashing md5     byte   md5Bytes   md5 asBytes    String md5Hex   md5 toString     HashCode crc32   Files hash file  Hashing crc32     int crc32Int   crc32 asInt        the Checksum API returns a long  but it s padded with 0s for 32-bit CRC    this is the value you would get if using that API directly long checksumResult   crc32 padToLong

User · Answer

String checksum   DigestUtils md5Hex new FileInputStream filePath

User · Answer

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  gt  0                                md5Hash update buffer  0  numRead                                   input close             byte    md5Bytes   md5Hash digest            for  int i 0  i  lt  md5Bytes length  i                          returnVal    Integer toString    md5Bytes i   amp  0xff     0x100  16  substring  1                         catch Throwable t   t printStackTrace         return returnVal toUpperCase

User · Answer

There s an example at Real s Java-How-to using the MessageDigest class   Check that page for examples using CRC32 and SHA-1 as well   import java io    import java security MessageDigest   public class MD5Checksum       public static byte   createChecksum String filename  throws Exception          InputStream fis    new FileInputStream filename           byte   buffer   new byte 1024          MessageDigest complete   MessageDigest getInstance  MD5           int numRead          do              numRead   fis read buffer              if  numRead  gt  0                   complete update buffer  0  numRead                         while  numRead    -1           fis close           return complete digest                see this How-to for a faster way to convert       a byte array to a HEX string    public static String getMD5Checksum String filename  throws Exception          byte   b   createChecksum filename          String result               for  int i 0  i  lt  b length  i                 result    Integer toString    b i   amp  0xff     0x100  16  substring  1                    return result           public static void main String args             try              System out println getMD5Checksum  apache-tomcat-5 5 17 exe                   output                  0bb2827c5eacf570b6064e24e0e6653b               ref                  http   www apache org dist                         tomcat tomcat-5 v5 5 17 bin                             apache-tomcat-5 5 17 exe MD5                0bb2827c5eacf570b6064e24e0e6653b  apache-tomcat-5 5 17 exe                 catch  Exception e               e printStackTrace

User · Answer

Here is a handy variation that makes use of InputStream transferTo   from Java 9  and OutputStream nullOutputStream   from Java 11  It requires no external libraries and does not need to load the entire file into memory   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       returns    e30fa2784ba15be37833d569280e2163c6f106506dfb9b07dde67a24bfb90da65c661110cf2c5c6f71185754ee5ae3fd83a5465c92f72abd888b03187229da29

User · Answer

Using nio2  Java 7   and no external libraries   byte   b   Files readAllBytes Paths get   path to file     byte   hash   MessageDigest getInstance  MD5   digest b     To compare the result with an expected checksum   String expected    2252290BC44BEAD16AA1BF89948472E8   String actual   DatatypeConverter printHexBinary hash   System out println expected equalsIgnoreCase actual     MATCH     NO MATCH

User · Answer

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  gt  0                                md5Hash update buffer  0  numRead                                   input close             byte    md5Bytes   md5Hash digest            for  int i 0  i  lt  md5Bytes length  i                          returnVal    Integer toString    md5Bytes i   amp  0xff     0x100  16  substring  1                         catch Throwable t   t printStackTrace         return returnVal toUpperCase

User · Answer

Use DigestUtils from Apache Commons Codec library   try  InputStream is   Files newInputStream Paths get  file zip           String md5   org apache commons codec digest DigestUtils md5Hex is

User · Answer

Here is a simple function that wraps around Sunil s code so that it takes a File as a parameter  The function does not need any external libraries  but it does require Java 7   import java io File  import java io IOException  import java nio file Files  import java security MessageDigest  import java security NoSuchAlgorithmException   import javax xml bind DatatypeConverter   public class Checksum                   Generates an MD5 checksum as a String          param file The file that is being checksummed          return Hex string of the checksum value          throws NoSuchAlgorithmException         throws IOException             public static String generate File file  throws NoSuchAlgorithmException IOException            MessageDigest messageDigest   MessageDigest getInstance  MD5            messageDigest update Files readAllBytes file toPath              byte   hash   messageDigest digest             return DatatypeConverter printHexBinary hash  toUpperCase               public static void main String argv    throws NoSuchAlgorithmException  IOException           File file   new File   Users foo bar Documents file jar                      String hex   Checksum generate file           System out printf  hex  s n   hex                           Example output   hex B117DD0C3CBBD009AC4EF65B6D75C97B

User · Answer

There s an example at Real s Java-How-to using the MessageDigest class   Check that page for examples using CRC32 and SHA-1 as well   import java io    import java security MessageDigest   public class MD5Checksum       public static byte   createChecksum String filename  throws Exception          InputStream fis    new FileInputStream filename           byte   buffer   new byte 1024          MessageDigest complete   MessageDigest getInstance  MD5           int numRead          do              numRead   fis read buffer              if  numRead  gt  0                   complete update buffer  0  numRead                         while  numRead    -1           fis close           return complete digest                see this How-to for a faster way to convert       a byte array to a HEX string    public static String getMD5Checksum String filename  throws Exception          byte   b   createChecksum filename          String result               for  int i 0  i  lt  b length  i                 result    Integer toString    b i   amp  0xff     0x100  16  substring  1                    return result           public static void main String args             try              System out println getMD5Checksum  apache-tomcat-5 5 17 exe                   output                  0bb2827c5eacf570b6064e24e0e6653b               ref                  http   www apache org dist                         tomcat tomcat-5 v5 5 17 bin                             apache-tomcat-5 5 17 exe MD5                0bb2827c5eacf570b6064e24e0e6653b  apache-tomcat-5 5 17 exe                 catch  Exception e               e printStackTrace

User · Answer

I recently had to do this for just a dynamic string, MessageDigest can represent the hash in numerous ways. To get the signature of the file like you would get with the md5sum command I had to do something like the this:

try {
   String s = "TEST STRING";
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   md5.update(s.getBytes(),0,s.length());
   String signature = new BigInteger(1,md5.digest()).toString(16);
   System.out.println("Signature: "+signature);

} catch (final NoSuchAlgorithmException e) {
   e.printStackTrace();
}

This obviously doesn't answer your question about how to do it specifically for a file, the above answer deals with that quiet nicely. I just spent a lot of time getting the sum to look like most application's display it, and thought you might run into the same trouble.

User · Answer

We were using code that resembles the code above in a previous post using      String signature   new BigInteger 1 md5 digest    toString 16         However  watch out for using BigInteger toString   here  as it will truncate leading zeros     for an example  try s    27   checksum should be  02e74f10e0327ad868d138f2b4fdd6f0     I second the suggestion to use Apache Commons Codec  I replaced our own code with that

User · Answer

There s an input stream decorator  java security DigestInputStream  so that you can compute the digest while using the input stream as you normally would  instead of having to make an extra pass over the data   MessageDigest md   MessageDigest getInstance  MD5    try  InputStream is   Files newInputStream Paths get  file txt          DigestInputStream dis   new DigestInputStream is  md           Read decorated stream  dis  to EOF as normal         byte   digest   md digest

User · Answer

There s an input stream decorator  java security DigestInputStream  so that you can compute the digest while using the input stream as you normally would  instead of having to make an extra pass over the data   MessageDigest md   MessageDigest getInstance  MD5    try  InputStream is   Files newInputStream Paths get  file txt          DigestInputStream dis   new DigestInputStream is  md           Read decorated stream  dis  to EOF as normal         byte   digest   md digest

User · Answer

There s an input stream decorator  java security DigestInputStream  so that you can compute the digest while using the input stream as you normally would  instead of having to make an extra pass over the data   MessageDigest md   MessageDigest getInstance  MD5    try  InputStream is   Files newInputStream Paths get  file txt          DigestInputStream dis   new DigestInputStream is  md           Read decorated stream  dis  to EOF as normal         byte   digest   md digest

User · Answer

Ok  I had to add  One line implementation for those who already have Spring and Apache Commons dependency or are planning to add it   DigestUtils md5DigestAsHex FileUtils readFileToByteArray file     For and Apache commons only option  credit  duleshi    DigestUtils md5Hex FileUtils readFileToByteArray file     Hope this helps someone

User · Answer

Another implementation  Fast MD5 Implementation in Java  String hash   MD5 asHex MD5 getHash new File filename

User · Answer

Very fast  amp  clean Java-method that doesn t rely on external libraries    Simply replace MD5 with SHA-1  SHA-256  SHA-384 or SHA-512 if you want those   public String calcMD5   throws Exception          byte   buffer   new byte 8192           MessageDigest md   MessageDigest getInstance  MD5             DigestInputStream dis   new DigestInputStream new FileInputStream new File  Path to file     md           try               while  dis read buffer     -1            finally              dis close                       byte   bytes   md digest                bytesToHex-method         char   hexChars   new char bytes length   2           for   int j   0  j  lt  bytes length  j                   int v   bytes j   amp  0xFF              hexChars j   2    hexArray v  gt  gt  gt  4               hexChars j   2   1    hexArray v  amp  0x0F                      return new String hexChars

User · Answer

There s an input stream decorator  java security DigestInputStream  so that you can compute the digest while using the input stream as you normally would  instead of having to make an extra pass over the data   MessageDigest md   MessageDigest getInstance  MD5    try  InputStream is   Files newInputStream Paths get  file txt          DigestInputStream dis   new DigestInputStream is  md           Read decorated stream  dis  to EOF as normal         byte   digest   md digest

User · Answer

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  lt  mdbytes length  i              sb append Integer toString  mdbytes i   amp  0xff    0x100  16  substring 1              System out println  Digest in hex format        sb toString         Or you may get more info  http   www asjava com core-java java-md5-example

User · Answer

The com google common hash API offers    A unified user-friendly API for all hash functions Seedable 32- and 128-bit implementations of murmur3 md5    sha1    sha256    sha512   adapters  change only one line of code to switch between these  and murmur  goodFastHash int bits   for when you don t care what algorithm you use General utilities for HashCode instances  like combineOrdered   combineUnordered   Read the User Guide  IO Explained  Hashing Explained     For your use-case Files hash   computes and returns the digest value for a file   For example a sha-1 digest calculation  change SHA-1 to MD5 to get MD5 digest   HashCode hc   Files asByteSource file  hash Hashing sha1      SHA-1      hc toString      Note that crc32 is much faster than md5  so use crc32 if you do not need a cryptographically secure checksum  Note also that md5 should not be used to store passwords and the like since it is to easy to brute force  for passwords use bcrypt   scrypt or sha-256 instead    For long term protection with hashes a  Merkle signature scheme adds to the security and The Post Quantum Cryptography Study Group sponsored by the European Commission has recommended use of this cryptography for long term protection against quantum computers  ref    Note that crc32 has a higher collision rate than the others

User · Answer

We were using code that resembles the code above in a previous post using      String signature   new BigInteger 1 md5 digest    toString 16         However  watch out for using BigInteger toString   here  as it will truncate leading zeros     for an example  try s    27   checksum should be  02e74f10e0327ad868d138f2b4fdd6f0     I second the suggestion to use Apache Commons Codec  I replaced our own code with that

User · Answer

Guava now provides a new  consistent hashing API that is much more user-friendly than the various hashing APIs provided in the JDK  See Hashing Explained  For a file  you can get the MD5 sum  CRC32  with version 14 0   or many other hashes easily   HashCode md5   Files hash file  Hashing md5     byte   md5Bytes   md5 asBytes    String md5Hex   md5 toString     HashCode crc32   Files hash file  Hashing crc32     int crc32Int   crc32 asInt        the Checksum API returns a long  but it s padded with 0s for 32-bit CRC    this is the value you would get if using that API directly long checksumResult   crc32 padToLong

User · Answer

Here is a simple function that wraps around Sunil s code so that it takes a File as a parameter  The function does not need any external libraries  but it does require Java 7   import java io File  import java io IOException  import java nio file Files  import java security MessageDigest  import java security NoSuchAlgorithmException   import javax xml bind DatatypeConverter   public class Checksum                   Generates an MD5 checksum as a String          param file The file that is being checksummed          return Hex string of the checksum value          throws NoSuchAlgorithmException         throws IOException             public static String generate File file  throws NoSuchAlgorithmException IOException            MessageDigest messageDigest   MessageDigest getInstance  MD5            messageDigest update Files readAllBytes file toPath              byte   hash   messageDigest digest             return DatatypeConverter printHexBinary hash  toUpperCase               public static void main String argv    throws NoSuchAlgorithmException  IOException           File file   new File   Users foo bar Documents file jar                      String hex   Checksum generate file           System out printf  hex  s n   hex                           Example output   hex B117DD0C3CBBD009AC4EF65B6D75C97B

User · Answer

Standard Java Runtime Environment way   public String checksum File file      try       InputStream fin   new FileInputStream file       java security MessageDigest md5er           MessageDigest getInstance  MD5        byte   buffer   new byte 1024       int read      do         read   fin read buffer         if  read  gt  0          md5er update buffer  0  read         while  read    -1       fin close        byte   digest   md5er digest        if  digest    null        return null      String strDigest    0x       for  int i   0  i  lt  digest length  i            strDigest    Integer toString  digest i   amp  0xff                     0x100  16  substring 1  toUpperCase              return strDigest      catch  Exception e        return null          The result is equal of linux md5sum utility

User · Answer

Standard Java Runtime Environment way   public String checksum File file      try       InputStream fin   new FileInputStream file       java security MessageDigest md5er           MessageDigest getInstance  MD5        byte   buffer   new byte 1024       int read      do         read   fin read buffer         if  read  gt  0          md5er update buffer  0  read         while  read    -1       fin close        byte   digest   md5er digest        if  digest    null        return null      String strDigest    0x       for  int i   0  i  lt  digest length  i            strDigest    Integer toString  digest i   amp  0xff                     0x100  16  substring 1  toUpperCase              return strDigest      catch  Exception e        return null          The result is equal of linux md5sum utility

User · Answer

Another implementation  Fast MD5 Implementation in Java  String hash   MD5 asHex MD5 getHash new File filename

User · Answer

A simple approach with no third party libraries using Java 7  String path    your complete file path   MessageDigest md   MessageDigest getInstance  MD5    md update Files readAllBytes Paths get path     byte   digest   md digest      If you need to print this byte array  Use as below  System out println Arrays toString digest      If you need hex string out of this digest  Use as below  String digestInHex   DatatypeConverter printHexBinary digest  toUpperCase    System out println digestInHex     where DatatypeConverter is javax xml bind DatatypeConverter

User · Answer

Very fast  amp  clean Java-method that doesn t rely on external libraries    Simply replace MD5 with SHA-1  SHA-256  SHA-384 or SHA-512 if you want those   public String calcMD5   throws Exception          byte   buffer   new byte 8192           MessageDigest md   MessageDigest getInstance  MD5             DigestInputStream dis   new DigestInputStream new FileInputStream new File  Path to file     md           try               while  dis read buffer     -1            finally              dis close                       byte   bytes   md digest                bytesToHex-method         char   hexChars   new char bytes length   2           for   int j   0  j  lt  bytes length  j                   int v   bytes j   amp  0xFF              hexChars j   2    hexArray v  gt  gt  gt  4               hexChars j   2   1    hexArray v  amp  0x0F                      return new String hexChars

User · Answer

A simple approach with no third party libraries using Java 7  String path    your complete file path   MessageDigest md   MessageDigest getInstance  MD5    md update Files readAllBytes Paths get path     byte   digest   md digest      If you need to print this byte array  Use as below  System out println Arrays toString digest      If you need hex string out of this digest  Use as below  String digestInHex   DatatypeConverter printHexBinary digest  toUpperCase    System out println digestInHex     where DatatypeConverter is javax xml bind DatatypeConverter

User · Answer

public static String MD5Hash String toHash  throws RuntimeException      try         return String format   032x      produces lower case 32 char wide hexa left-padded with 0       new BigInteger 1     handles large POSITIVE numbers             MessageDigest getInstance  MD5   digest toHash getBytes               catch  NoSuchAlgorithmException e             do whatever seems relevant

User · Answer

Google guava provides a new API  Find the one below    public static HashCode hash File file              HashFunction hashFunction                       throws IOException  Computes the hash code of the file using hashFunction   Parameters      file - the file to read     hashFunction - the hash function to use to hash the data Returns      the HashCode of all of the bytes in the file Throws      IOException - if an I O error occurs Since      12 0

User · Answer

Google guava provides a new API  Find the one below    public static HashCode hash File file              HashFunction hashFunction                       throws IOException  Computes the hash code of the file using hashFunction   Parameters      file - the file to read     hashFunction - the hash function to use to hash the data Returns      the HashCode of all of the bytes in the file Throws      IOException - if an I O error occurs Since      12 0

User · Answer

If you re using ANT to build  this is dead-simple   Add the following to your build xml    lt checksum file    jarFile   todir    toDir    gt    Where jarFile is the JAR you want to generate the MD5 against  and toDir is the directory you want to place the MD5 file   More info here

User · Answer

There s an example at Real s Java-How-to using the MessageDigest class   Check that page for examples using CRC32 and SHA-1 as well   import java io    import java security MessageDigest   public class MD5Checksum       public static byte   createChecksum String filename  throws Exception          InputStream fis    new FileInputStream filename           byte   buffer   new byte 1024          MessageDigest complete   MessageDigest getInstance  MD5           int numRead          do              numRead   fis read buffer              if  numRead  gt  0                   complete update buffer  0  numRead                         while  numRead    -1           fis close           return complete digest                see this How-to for a faster way to convert       a byte array to a HEX string    public static String getMD5Checksum String filename  throws Exception          byte   b   createChecksum filename          String result               for  int i 0  i  lt  b length  i                 result    Integer toString    b i   amp  0xff     0x100  16  substring  1                    return result           public static void main String args             try              System out println getMD5Checksum  apache-tomcat-5 5 17 exe                   output                  0bb2827c5eacf570b6064e24e0e6653b               ref                  http   www apache org dist                         tomcat tomcat-5 v5 5 17 bin                             apache-tomcat-5 5 17 exe MD5                0bb2827c5eacf570b6064e24e0e6653b  apache-tomcat-5 5 17 exe                 catch  Exception e               e printStackTrace

User · Answer

Using nio2  Java 7   and no external libraries   byte   b   Files readAllBytes Paths get   path to file     byte   hash   MessageDigest getInstance  MD5   digest b     To compare the result with an expected checksum   String expected    2252290BC44BEAD16AA1BF89948472E8   String actual   DatatypeConverter printHexBinary hash   System out println expected equalsIgnoreCase actual     MATCH     NO MATCH

User · Answer

Use DigestUtils from Apache Commons Codec library   try  InputStream is   Files newInputStream Paths get  file zip           String md5   org apache commons codec digest DigestUtils md5Hex is

[java] Getting a File's MD5 Checksum in Java

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