java.lang.Object
- org.apache.commons.io.filefilter.AbstractFileFilter
- - org.apache.commons.io.filefilter.MagicNumberFileFilter

All Implemented Interfaces:: java.io.FileFilter, java.io.FilenameFilter, java.io.Serializable, java.nio.file.FileVisitor<java.nio.file.Path>, PathFilter, PathVisitor, IOFileFilter

public class MagicNumberFileFilter
extends AbstractFileFilter
implements java.io.Serializable

File filter for matching files containing a "magic number". A magic number is a unique series of bytes common to all files of a specific file format. For instance, all Java class files begin with the bytes 0xCAFEBABE.

Using Classic IO

 File dir = FileUtils.current();
 MagicNumberFileFilter javaClassFileFilter =
     MagicNumberFileFilter(new byte[] {(byte) 0xCA, (byte) 0xFE,
       (byte) 0xBA, (byte) 0xBE});
 String[] javaClassFiles = dir.list(javaClassFileFilter);
 for (String javaClassFile : javaClassFiles) {
     System.out.println(javaClassFile);
 }

Sometimes, such as in the case of TAR files, the magic number will be offset by a certain number of bytes in the file. In the case of TAR archive files, this offset is 257 bytes.

 File dir = FileUtils.current();
 MagicNumberFileFilter tarFileFilter =
     MagicNumberFileFilter("ustar", 257);
 String[] tarFiles = dir.list(tarFileFilter);
 for (String tarFile : tarFiles) {
     System.out.println(tarFile);
 }

Using NIO

 final Path dir = PathUtils.current();
 final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(MagicNumberFileFilter("ustar", 257));
 //
 // Walk one dir
 Files.walkFileTree(dir, Collections.emptySet(), 1, visitor);
 System.out.println(visitor.getPathCounters());
 System.out.println(visitor.getFileList());
 //
 visitor.getPathCounters().reset();
 //
 // Walk dir tree
 Files.walkFileTree(dir, visitor);
 System.out.println(visitor.getPathCounters());
 System.out.println(visitor.getDirList());
 System.out.println(visitor.getFileList());

Deprecating Serialization

Serialization is deprecated and will be removed in 3.0.

Deprecating Serialization

Serialization is deprecated and will be removed in 3.0.

Since:: 2.0
See Also:: FileFilterUtils.magicNumberFileFilter(byte[]), FileFilterUtils.magicNumberFileFilter(String), FileFilterUtils.magicNumberFileFilter(byte[], long), FileFilterUtils.magicNumberFileFilter(String, long), Serialized Form

Field Summary
- Fields inherited from interface org.apache.commons.io.filefilter.IOFileFilter
  EMPTY_STRING_ARRAY

Constructor Summary

Constructors
Constructor	Description
`MagicNumberFileFilter(byte[] magicNumber)`	Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files.
`MagicNumberFileFilter(byte[] magicNumbers, long offset)`	Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files and the byte offset location in the file to to look for that magic number.
`MagicNumberFileFilter(java.lang.String magicNumber)`	Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files.
`MagicNumberFileFilter(java.lang.String magicNumber, long offset)`	Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files and the byte offset location in the file to to look for that magic number.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`accept(java.io.File file)`	Accepts the provided file if the file contains the file filter's magic number at the specified offset.
`java.nio.file.FileVisitResult`	`accept(java.nio.file.Path file, java.nio.file.attribute.BasicFileAttributes attributes)`	Accepts the provided file if the file contains the file filter's magic number at the specified offset.
`java.lang.String`	`toString()`	Returns a String representation of the file filter, which includes the magic number bytes and byte offset.

Methods inherited from class org.apache.commons.io.filefilter.AbstractFileFilter
accept, postVisitDirectory, preVisitDirectory, visitFile, visitFileFailed

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

Methods inherited from interface org.apache.commons.io.filefilter.IOFileFilter
and, negate, or

- Constructor Detail
  - MagicNumberFileFilter
```
public MagicNumberFileFilter(byte[] magicNumber)
```
    Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files. This constructor assumes a starting offset of 0.
    
    It is important to note that the array is not cloned and that any changes to the magic number array after construction will affect the behavior of this file filter.
    
    MagicNumberFileFilter javaClassFileFilter = MagicNumberFileFilter(new byte[] {(byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE});
    Parameters:
    
    magicNumber - the magic number to look for in the file.
    
    Throws:
    
    java.lang.IllegalArgumentException - if magicNumber is null, or contains no bytes.
  - MagicNumberFileFilter
```
public MagicNumberFileFilter(byte[] magicNumbers,
                             long offset)
```
    Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files and the byte offset location in the file to to look for that magic number.
    
    MagicNumberFileFilter tarFileFilter = MagicNumberFileFilter(new byte[] {0x75, 0x73, 0x74, 0x61, 0x72}, 257);
    
    MagicNumberFileFilter javaClassFileFilter = MagicNumberFileFilter(new byte[] {0xCA, 0xFE, 0xBA, 0xBE}, 0);
    Parameters:
    
    magicNumbers - the magic number to look for in the file.
    
    offset - the byte offset in the file to start comparing bytes.
    
    Throws:
    
    java.lang.IllegalArgumentException - if magicNumber contains no bytes, or offset is a negative number.
  - MagicNumberFileFilter
```
public MagicNumberFileFilter(java.lang.String magicNumber)
```
    Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files. This constructor assumes a starting offset of 0.
    Example usage:
    MagicNumberFileFilter xmlFileFilter = MagicNumberFileFilter("<?xml");
    Parameters:
    
    magicNumber - the magic number to look for in the file. The string is converted to bytes using the platform default charset.
    
    Throws:
    
    java.lang.IllegalArgumentException - if magicNumber is null or the empty String.
  - MagicNumberFileFilter
```
public MagicNumberFileFilter(java.lang.String magicNumber,
                             long offset)
```
    Constructs a new MagicNumberFileFilter and associates it with the magic number to test for in files and the byte offset location in the file to to look for that magic number.
    
    MagicNumberFileFilter tarFileFilter = MagicNumberFileFilter("ustar", 257);
    Parameters:
    
    magicNumber - the magic number to look for in the file. The string is converted to bytes using the platform default charset.
    
    offset - the byte offset in the file to start comparing bytes.
    
    Throws:
    
    java.lang.IllegalArgumentException - if magicNumber is the empty String, or offset is a negative number.
- Method Detail
  - accept
```
public boolean accept(java.io.File file)
```
    Accepts the provided file if the file contains the file filter's magic number at the specified offset.
    
    If any IOExceptions occur while reading the file, the file will be rejected.
    
    Specified by:
    
    accept in interface java.io.FileFilter
    
    Specified by:
    
    accept in interface IOFileFilter
    
    Overrides:
    
    accept in class AbstractFileFilter
    
    Parameters:
    
    file - the file to accept or reject.
    
    Returns:
    
    true if the file contains the filter's magic number at the specified offset, false otherwise.
  - accept
```
public java.nio.file.FileVisitResult accept(java.nio.file.Path file,
                                            java.nio.file.attribute.BasicFileAttributes attributes)
```
    Accepts the provided file if the file contains the file filter's magic number at the specified offset.
    
    If any IOExceptions occur while reading the file, the file will be rejected.
    
    Specified by:
    
    accept in interface IOFileFilter
    
    Specified by:
    
    accept in interface PathFilter
    
    Parameters:
    
    file - the file to accept or reject.
    
    attributes - the file's basic attributes (TODO may be null).
    
    Returns:
    
    true if the file contains the filter's magic number at the specified offset, false otherwise.
    
    Since:
    
    2.9.0
  - toString
```
public java.lang.String toString()
```
    Returns a String representation of the file filter, which includes the magic number bytes and byte offset.
    
    Overrides:
    
    toString in class AbstractFileFilter
    
    Returns:
    
    a String representation of the file filter.

Class MagicNumberFileFilter

Using Classic IO

Using NIO

Deprecating Serialization

Deprecating Serialization

Field Summary

Fields inherited from interface org.apache.commons.io.filefilter.IOFileFilter

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.io.filefilter.AbstractFileFilter

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.commons.io.filefilter.IOFileFilter

Constructor Detail

MagicNumberFileFilter

MagicNumberFileFilter

MagicNumberFileFilter

MagicNumberFileFilter

Method Detail

accept

accept

toString