All Known Implementing Classes:

XFileAccessor, XFileAccessor, XFileAccessor, XFileAccessor
```
public interface XFileAccessor
```
The XFileAccessor interface is implemented by filesystems that need to be accessed via the XFile API. Classes that implement this interface must be associated with a URL scheme that is structured according to the Common Internet Scheme syntax described in RFC 1738; an optional location part followed by a hierarchical set of slash separated directories.
A class file that implements this interface must be named "XFileAccessor" and be installed in a directory named after the URL scheme that it implements, for instance, an XFileAccessor that provides file access through the HTTP protocol would be associated with the "http" URL and its class file would be called:
http.XFileAccessor
A class prefix is added to this name. The default prefix is com.sun and this composite name is located by the classLoader via the CLASSPATH. For instance, Sun's "nfs" XFileAccessor is installed as:
com.sun.nfs.XFileAccessor
The default class prefix com.sun can be changed by setting the System property java.protocol.xfile to any desired prefix or a list of prefixes separated by vertical bars. Each prefix in the list will be used to construct a package name and the classLoader will attempt to load that package via the CLASSPATH. This process will continue until the XFileAccessor is successfully loaded.
For instance, if you want to use the "ftp" XFileAccessor from Acme, Inc and the "nfs" XFileAccessor from "ABC Inc." then you can set the system property as follows:
java.protocol.xfile=com.acme|com.abc
When an "ftp" URL is used, the following package names will be constructed:
```
    com.acme.ftp.XFileAccessor
    com.abc.ftp.XFileAccessor
    com.sun.ftp.XFileAccessor
 
```
(the default "com.sun" prefix is automatically added to the end of the property list)
The class loader attempts to load each of the constructed package names in turn relative to the CLASSPATH until it is successful.
A subsequent reference to an "nfs" URL will result in the following list of candidate package names:
```
    com.acme.nfs.XFileAccessor
    com.abc.nfs.XFileAccessor
    com.sun.nfs.XFileAccessor
 
```
In this case the "nfs" XFileAccessor from ABC, Inc. will be loaded in preference to Sun's NFS.
Version:

1.0, 04/08/98

Author:

Brent Callaghan

See Also:

XFile

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`canRead()`	Tests if the application can read from the specified file.
`boolean`	`canWrite()`	Tests if the application can write to this file.
`void`	`close()`	Close the file.
`boolean`	`delete()`	Deletes the file specified by this object.
`boolean`	`exists()`	Tests if this XFile object exists.
`void`	`flush()`	Forces any buffered output bytes to be written out.
`XFile`	`getXFile()`	Return the XFile for this Accessor
`boolean`	`isDirectory()`	Tests if the file represented by this XFileAccessor object is a directory.
`boolean`	`isFile()`	Tests if the file represented by this object is a "normal" file.
`long`	`lastModified()`	Returns the time that the file represented by this `XFile` object was last modified.
`long`	`length()`	Returns the length of the file represented by this XFileAccessor object.
`java.lang.String[]`	`list()`	Returns a list of the files in the directory specified by this XFileAccessor object.
`boolean`	`mkdir()`	Creates a directory whose pathname is specified by this XFileAccessor object.
`boolean`	`mkfile()`	Creates an empty file whose pathname is specified by this XFileAccessor object.
`boolean`	`open(XFile xf, boolean serial, boolean readOnly)`	Open a file in this filesystem.
`int`	`read(byte[] b, int off, int len, long foff)`	Reads a subarray as a sequence of bytes.
`boolean`	`renameTo(XFile dest)`	Renames the file specified by this XFileAccessor object to have the pathname given by the XFileAccessor object argument.
`void`	`write(byte[] b, int off, int len, long foff)`	Writes a sub array as a sequence of bytes.

- Method Detail
  - open
```
boolean open(XFile xf,
             boolean serial,
             boolean readOnly)
```
    Open a file in this filesystem. This method is called before any other method. It may be used to open the real file.
    
    Parameters:
    
    xf - The XFile for the file to be accessed The URL will be of the form
    <proto>://<location>/<path>
    where <proto> is the name of the filesystem, e.g. "nfs" and <location> is the location of the filesystem. For nfs this is the network name of a server. The <path> is a pathname that locates the file within <location>. As required by RFC 1738, the component delimiters in the pathname are as for URL syntax: forward slashes only.
    
    serial - true if serial access; false if random access
    
    readOnly - true if read only; false if read/write
  - getXFile
```
XFile getXFile()
```
    Return the XFile for this Accessor
  - exists
```
boolean exists()
```
    Tests if this XFile object exists.
    
    Returns:
    
    true if the file specified by this object exists; false otherwise.
  - canWrite
```
boolean canWrite()
```
    Tests if the application can write to this file.
    
    Returns:
    
    true if the application is allowed to write to a file whose name is specified by this object; false otherwise.
  - canRead
```
boolean canRead()
```
    Tests if the application can read from the specified file.
    
    Returns:
    
    true if the file specified by this object exists and the application can read the file; false otherwise.
  - isFile
```
boolean isFile()
```
    Tests if the file represented by this object is a "normal" file.
    A file is "normal" if it is not a directory and, in addition, satisfies other system-dependent criteria. Any non-directory file created by a Java application is guaranteed to be a normal file.
    
    Returns:
    
    true if the file specified by this object exists and is a "normal" file; false otherwise.
  - isDirectory
```
boolean isDirectory()
```
    Tests if the file represented by this XFileAccessor object is a directory.
    
    Returns:
    
    true if this XFileAccessor object exists and is a directory; false otherwise.
  - lastModified
```
long lastModified()
```
    Returns the time that the file represented by this XFile object was last modified. It is measured as the time in milliseconds since midnight, January 1, 1970 UTC.
    
    Returns:
    
    the time the file specified by this object was last modified, or 0L if the specified file does not exist.
  - length
```
long length()
```
    Returns the length of the file represented by this XFileAccessor object.
    
    Returns:
    
    the length, in bytes, of the file specified by this object, or 0L if the specified file does not exist.
  - mkfile
```
boolean mkfile()
```
    Creates an empty file whose pathname is specified by this XFileAccessor object.
    
    Returns:
    
    true if the file was created; false otherwise.
  - mkdir
```
boolean mkdir()
```
    Creates a directory whose pathname is specified by this XFileAccessor object.
    
    Returns:
    
    true if the directory could be created; false otherwise.
  - renameTo
```
boolean renameTo(XFile dest)
```
    Renames the file specified by this XFileAccessor object to have the pathname given by the XFileAccessor object argument. The destination XFile object will be of the same URL scheme as this object. The change of name must not affect the existence or accessibility of this object.
    
    Parameters:
    
    dest - the new filename.
    
    Returns:
    
    true if the renaming succeeds; false otherwise.
  - delete
```
boolean delete()
```
    Deletes the file specified by this object. If the target file to be deleted is a directory, it must be empty for deletion to succeed.
    
    Returns:
    
    true if the file is successfully deleted; false otherwise.
  - list
```
java.lang.String[] list()
```
    Returns a list of the files in the directory specified by this XFileAccessor object.
    
    Returns:
    
    an array of file names in the specified directory. This list does not include the current directory or the parent directory ("." and ".." on Unix systems).
  - read
```
int read(byte[] b,
         int off,
         int len,
         long foff)
  throws java.io.IOException
```
    Reads a subarray as a sequence of bytes.
    
    Parameters:
    
    b - the buffer into which the data is read
    
    off - the start offset in the data buffer
    
    len - the maximum number of bytes to be read
    
    foff - the offset into the file
    
    Returns:
    
    number of bytes read - zero if none.
    
    Throws:
    
    java.io.IOException - If an I/O error has occurred.
  - write
```
void write(byte[] b,
           int off,
           int len,
           long foff)
    throws java.io.IOException
```
    Writes a sub array as a sequence of bytes.
    
    Parameters:
    
    b - the data to be written
    
    off - the start offset in the data in the buffer
    
    len - the number of bytes that are written
    
    foff - the offset into the file
    
    Throws:
    
    java.io.IOException - If an I/O error has occurred.
  - flush
```
void flush()
    throws java.io.IOException
```
    Forces any buffered output bytes to be written out.
    
    Throws:
    
    java.io.IOException - if an I/O error occurs.
  - close
```
void close()
    throws java.io.IOException
```
    Close the file. Closes this file and releases any system resources associated with the file. After the file is closed further I/O operations may throw IOException.
    
    Throws:
    
    java.io.IOException - If an I/O error has occurred.

Interface XFileAccessor

Method Summary

Method Detail

open

getXFile

exists

canWrite

canRead

isFile

isDirectory

lastModified

length

mkfile

mkdir

renameTo

delete

list

read

write

flush

close