ca.uqac.lif.fs

Class ReadZipFile

java.lang.Object

ca.uqac.lif.fs.RamDisk

ca.uqac.lif.fs.ReadZipFile

All Implemented Interfaces:

FileSystem

public class ReadZipFile
extends RamDisk

Exposes the contents of a zip archive as a read-only file system. Internally, the class descends from RamDisk; however, it does not extract the archive into memory: it only uses its parent's tree structure to store the listing of folders without having to re-scan the file entries in the zip archive every time an operation such as RamDisk.ls() is invoked. Only when readFrom(String) is called does the file system move the location of the pointer within the zip file stream to the appropriate location; the corresponding file is then extracted on the fly. This way, it is possible to interact with a large archive, without the need to completely uncompress it before use.

Author:

Sylvain Hallé

Nested Class Summary

Nested classes/interfaces inherited from class ca.uqac.lif.fs.RamDisk

RamDisk.RamdiskFileNode, RamDisk.RamdiskFileOutputStream, RamDisk.RamdiskFolderNode, RamDisk.RamdiskNode

Nested classes/interfaces inherited from interface ca.uqac.lif.fs.FileSystem

FileSystem.OpenState

Field Summary

Fields

Modifier and Type	Field and Description
protected java.io.InputStream	m_input The input stream from which the contents of the zip file is to be read.
protected java.util.zip.ZipInputStream	m_zipInput A stream to read from a zip file.

Fields inherited from class ca.uqac.lif.fs.RamDisk

m_currentDir, m_dirStack, m_root, m_state

Constructor Summary

Constructors

Constructor and Description
ReadZipFile(java.io.InputStream input) Creates a new zip file system in read mode.

Method Summary

Modifier and Type	Method and Description
void	close() Stops the interaction with the file system.
void	delete(java.lang.String path) Deletes a directory and all its contents.
protected java.util.zip.ZipEntry	getZipEntry(java.lang.String path) Gets the zip entry corresponding to a given path.
void	mkdir(java.lang.String path) Creates a directory if it does not exist.
void	open() Starts the interaction with the file system.
java.io.InputStream	readFrom(java.lang.String filename) Reads data from a file.
void	rmdir(java.lang.String path) Deletes a directory and all its contents.
java.io.OutputStream	writeTo(java.lang.String filename) Writes data to a file.

Methods inherited from class ca.uqac.lif.fs.RamDisk

chdir, createFileNode, createFolderNode, getSize, isDirectory, isFile, locate, locate, ls, ls, ls, popd, pushd, pwd

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_zipInput

protected java.util.zip.ZipInputStream m_zipInput

A stream to read from a zip file.

m_input

protected java.io.InputStream m_input

The input stream from which the contents of the zip file is to be read.

Constructor Detail

ReadZipFile

public ReadZipFile(java.io.InputStream input)

Creates a new zip file system in read mode.

Parameters:

input - The input stream from which the contents of the zip file is to be read

Method Detail

open

public void open()
          throws FileSystemException

Description copied from interface: FileSystem

Starts the interaction with the file system. All operations invoked on a file system will throw a FileSystemException if called before this method.

Specified by:

open in interface FileSystem

Overrides:

open in class RamDisk

Throws:

FileSystemException - Thrown if the interaction with the file system cannot be started

writeTo

public java.io.OutputStream writeTo(java.lang.String filename)
                             throws FileSystemException

Description copied from interface: FileSystem

Writes data to a file. The method provides an OutputStream to which data can be printed. The data is guaranteed to be committed to the file only when the print stream is closed. Whether data is written before that moment depends on the actual file system implementation.

Specified by:

writeTo in interface FileSystem

Overrides:

writeTo in class RamDisk

Parameters:

filename - The name of the file to which data is to be written

Returns:

An output stream open on the file. If the method successfully returns, it guarantees that this stream is not null

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

readFrom

public java.io.InputStream readFrom(java.lang.String filename)
                             throws FileSystemException

Description copied from interface: FileSystem

Reads data from a file. The method provides an InputStream from which data can be read. Consumers of this input stream have the responsibility to close the stream after usage.

Specified by:

readFrom in interface FileSystem

Overrides:

readFrom in class RamDisk

Parameters:

filename - The name of the file to which data is to be written

Returns:

A print stream open on the file. If the method successfully returns, it guarantees that this stream is not null

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

mkdir

public void mkdir(java.lang.String path)
           throws FileSystemException

Description copied from interface: FileSystem

Creates a directory if it does not exist.

Specified by:

mkdir in interface FileSystem

Overrides:

mkdir in class RamDisk

Parameters:

path - The directory to create. The string can contain a path relative to the current directory.

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

rmdir

public void rmdir(java.lang.String path)
           throws FileSystemException

Description copied from interface: FileSystem

Deletes a directory and all its contents.

Specified by:

rmdir in interface FileSystem

Overrides:

rmdir in class RamDisk

Parameters:

path - The directory to delete

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

delete

public void delete(java.lang.String path)
            throws FileSystemException

Description copied from interface: FileSystem

Deletes a directory and all its contents.

Specified by:

delete in interface FileSystem

Overrides:

delete in class RamDisk

Parameters:

path - The directory to delete

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

close

public void close()
           throws FileSystemException

Description copied from interface: FileSystem

Stops the interaction with the file system. All operations invoked on a file system will throw a FileSystemException if called after this method.

Specified by:

close in interface FileSystem

Overrides:

close in class RamDisk

Throws:

FileSystemException - Thrown if an error occurred while stopping the interaction with the file system

getZipEntry

protected java.util.zip.ZipEntry getZipEntry(java.lang.String path)
                                      throws java.io.IOException

Gets the zip entry corresponding to a given path. This method has the side effect of placing the pointer of the zip input stream at the location of the desired file.

Parameters:

path - The path to get the entry for

Returns:

The zip entry

Throws:

java.io.IOException - Thrown if resetting the input stream fails