Package org.apache.hadoop.io

Class MD5Hash

java.lang.Object
org.apache.hadoop.io.MD5Hash
All Implemented Interfaces:
Comparable<MD5Hash>, Writable, WritableComparable<MD5Hash>
@Public @Stable public class MD5Hash extends Object implements WritableComparable<MD5Hash>
A Writable for MD5 hash values.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    org.apache.hadoop.io.MD5Hash.Comparator
    A WritableComparator optimized for MD5Hash keys.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    MD5_LEN
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    MD5Hash()
    Constructs an MD5Hash.
    MD5Hash(byte[] digest)
    Constructs an MD5Hash with a specified value.
    MD5Hash(String hex)
    Constructs an MD5Hash from a hex string.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    compareTo(MD5Hash that)
    Compares this object with the specified object for order.
    static MD5Hash
    digest(byte[] data)
    Construct a hash value for a byte array.
    static MD5Hash
    digest(byte[][] dataArr, int start, int len)
    Construct a hash value for an array of byte array.
    static MD5Hash
    digest(byte[] data, int start, int len)
    Construct a hash value for a byte array.
    static MD5Hash
    digest(InputStream in)
    Construct a hash value for the content from the InputStream.
    static MD5Hash
    digest(String string)
    Construct a hash value for a String.
    static MD5Hash
    digest(org.apache.hadoop.io.UTF8 utf8)
    Construct a hash value for a String.
    boolean
    equals(Object o)
    Returns true iff o is an MD5Hash whose digest contains the same values.
    byte[]
    getDigest()
    Returns the digest bytes.
    static MessageDigest
    getDigester()
    Create a thread local MD5 digester.
    long
    halfDigest()
    Construct a half-sized version of this MD5.
    int
    hashCode()
    Returns a hash code value for this object.
    int
    quarterDigest()
    Return a 32-bit digest of the MD5.
    static MD5Hash
    read(DataInput in)
    Constructs, reads and returns an instance.
    void
    readFields(DataInput in)
    Deserialize the fields of this object from in.
    void
    set(MD5Hash that)
    Copy the contents of another instance into this instance.
    void
    setDigest(String hex)
    Sets the digest value from a hex string.
    String
    toString()
    Returns a string representation of this object.
    void
    write(DataOutput out)
    Serialize the fields of this object to out.

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

  • Field Details

  • Constructor Details

    • MD5Hash

      public MD5Hash()
      Constructs an MD5Hash.

    • MD5Hash

      public MD5Hash(String hex)
      Constructs an MD5Hash from a hex string.
      Parameters:
      hex - input hex.

    • MD5Hash

      public MD5Hash(byte[] digest)
      Constructs an MD5Hash with a specified value.
      Parameters:
      digest - digest.

  • Method Details

    • readFields

      public void readFields(DataInput in) throws IOException
      Description copied from interface: Writable
      Deserialize the fields of this object from in.

      For efficiency, implementations should attempt to re-use storage in the existing object where possible.

      Specified by:
      readFields in interface Writable
      Parameters:
      in - DataInput to deseriablize this object from.
      Throws:
      IOException - any other problem for readFields.

    • read

      public static MD5Hash read(DataInput in) throws IOException
      Constructs, reads and returns an instance.
      Parameters:
      in - in.
      Returns:
      MD5Hash.
      Throws:
      IOException - raised on errors performing I/O.

    • write

      public void write(DataOutput out) throws IOException
      Description copied from interface: Writable
      Serialize the fields of this object to out.
      Specified by:
      write in interface Writable
      Parameters:
      out - DataOuput to serialize this object into.
      Throws:
      IOException - any other problem for write.

    • set

      public void set(MD5Hash that)
      Copy the contents of another instance into this instance.
      Parameters:
      that - that.

    • getDigest

      public byte[] getDigest()
      Returns the digest bytes.
      Returns:
      digest.

    • digest

      public static MD5Hash digest(byte[] data)
      Construct a hash value for a byte array.
      Parameters:
      data - data.
      Returns:
      MD5Hash.

    • getDigester

      public static MessageDigest getDigester()
      Create a thread local MD5 digester.
      Returns:
      MessageDigest.

    • digest

      public static MD5Hash digest(InputStream in) throws IOException
      Construct a hash value for the content from the InputStream.
      Parameters:
      in - input stream.
      Returns:
      MD5Hash.
      Throws:
      IOException - raised on errors performing I/O.

    • digest

      public static MD5Hash digest(byte[] data, int start, int len)
      Construct a hash value for a byte array.
      Parameters:
      data - data.
      start - start.
      len - len.
      Returns:
      MD5Hash.

    • digest

      public static MD5Hash digest(byte[][] dataArr, int start, int len)
      Construct a hash value for an array of byte array.
      Parameters:
      dataArr - dataArr.
      start - start.
      len - len.
      Returns:
      MD5Hash.

    • digest

      public static MD5Hash digest(String string)
      Construct a hash value for a String.
      Parameters:
      string - string.
      Returns:
      MD5Hash.

    • digest

      public static MD5Hash digest(org.apache.hadoop.io.UTF8 utf8)
      Construct a hash value for a String.
      Parameters:
      utf8 - utf8.
      Returns:
      MD5Hash.

    • halfDigest

      public long halfDigest()
      Construct a half-sized version of this MD5. Fits in a long.
      Returns:
      halfDigest.

    • quarterDigest

      public int quarterDigest()
      Return a 32-bit digest of the MD5.
      Returns:
      the first 4 bytes of the md5

    • equals

      public boolean equals(Object o)
      Returns true iff o is an MD5Hash whose digest contains the same values.
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Returns a hash code value for this object. Only uses the first 4 bytes, since md5s are evenly distributed.
      Overrides:
      hashCode in class Object

    • compareTo

      public int compareTo(MD5Hash that)
      Compares this object with the specified object for order.
      Specified by:
      compareTo in interface Comparable<MD5Hash>

    • toString

      public String toString()
      Returns a string representation of this object.
      Overrides:
      toString in class Object

    • setDigest

      public void setDigest(String hex)
      Sets the digest value from a hex string.
      Parameters:
      hex - hex.