MessageDigestInputStream

java.lang.Object
- java.io.InputStream
- - java.io.FilterInputStream
  - - org.apache.commons.io.input.ProxyInputStream
    - - org.apache.commons.io.input.ObservableInputStream
      - org.apache.commons.io.input.MessageDigestInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable
```
public final class MessageDigestInputStream
extends ObservableInputStream
```
This class is an example for using an ObservableInputStream. It creates its own ObservableInputStream.Observer, which calculates a checksum using a MessageDigest, for example, a SHA-512 sum.
To build an instance, use MessageDigestInputStream.Builder.

See the MessageDigest section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.

You must specify a message digest algorithm name or instance.

Note: Neither ObservableInputStream, nor MessageDigest, are thread safe, so is MessageDigestInputStream.

Since:

2.15.0

See Also:

MessageDigestInputStream.Builder

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static class`	`MessageDigestInputStream.Builder`	Builds new `MessageDigestInputStream`.
`static class`	`MessageDigestInputStream.MessageDigestMaintainingObserver`	Maintains the message digest.

Nested classes/interfaces inherited from class org.apache.commons.io.input.ObservableInputStream
ObservableInputStream.Observer

Field Summary

Fields
Modifier and Type Field Description

private java.security.MessageDigest messageDigest
- Fields inherited from class java.io.FilterInputStream
  in

Constructor Summary

Constructors
Modifier	Constructor	Description
`private`	`MessageDigestInputStream(java.io.InputStream inputStream, java.security.MessageDigest messageDigest)`	Constructs a new instance, which calculates a signature on the given stream, using the given `MessageDigest`.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static MessageDigestInputStream.Builder`	`builder()`	Constructs a new `MessageDigestInputStream.Builder`.
`java.security.MessageDigest`	`getMessageDigest()`	Gets the `MessageDigest`, which is being used for generating the checksum.

Methods inherited from class org.apache.commons.io.input.ObservableInputStream
add, close, consume, getObservers, noteClosed, noteDataByte, noteDataBytes, noteError, noteFinished, read, read, read, remove, removeAllObservers

Methods inherited from class org.apache.commons.io.input.ProxyInputStream
afterRead, available, beforeRead, handleIOException, mark, markSupported, reset, skip, unwrap

Methods inherited from class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - messageDigest
```
private final java.security.MessageDigest messageDigest
```
- Constructor Detail
  - MessageDigestInputStream
```
private MessageDigestInputStream(java.io.InputStream inputStream,
                                 java.security.MessageDigest messageDigest)
```
    Constructs a new instance, which calculates a signature on the given stream, using the given MessageDigest.
    The MD5 cryptographic algorithm is weak and should not be used.
    
    Parameters:
    
    inputStream - the stream to calculate the message digest for
    
    messageDigest - the message digest to use
    
    Throws:
    
    java.lang.NullPointerException - if messageDigest is null.
- Method Detail
  - builder
```
public static MessageDigestInputStream.Builder builder()
```
    Constructs a new MessageDigestInputStream.Builder.
    
    Returns:
    
    a new MessageDigestInputStream.Builder.
  - getMessageDigest
```
public java.security.MessageDigest getMessageDigest()
```
    Gets the MessageDigest, which is being used for generating the checksum.
    Note: The checksum will only reflect the data, which has been read so far. This is probably not, what you expect. Make sure, that the complete data has been read, if that is what you want. The easiest way to do so is by invoking ObservableInputStream.consume().
    
    Returns:
    
    the message digest used