com.dalsemi.onewire.utils
Class OWFileInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--com.dalsemi.onewire.utils.OWFileInputStream

public class OWFileInputStream

extends InputStream

A OWFileInputStream obtains input bytes from a file in a 1-Wire Filesystem. What files are available depends on the 1-Wire device.

Note that the 1-Wire File system can reside across multiple 1-Wire devices. In this case only one of the devices need be supplied to the constructor. Each device in a multi-device file system contains information to reacquire the entire list.

File and directory name limitations

• File/directory names limited to 4 characters not including extension
• File/directory names are not case sensitive and will be automatically changed to all-CAPS
• Only files can have extensions
• Extensions are numberical in the range 0 to 125
• Extensions 100 to 125 are special purpose and not yet implemented or allowed
• Files can have the read-only attribute
• Directories can have the hidden attribute
• It is recommended to limit directory depth to 10 levels to accomodate legacy implementations

Usage

Example

Read from a 1-Wire file on device 'owd':

 
   // get an input stream to the 1-Wire file 
   OWFileInputStream instream = new OWFileInputStream(owd, "DEMO.0");

   // read some data
   byte[] data = new byte[2000];
   int len = instream.read(data);

   // close the stream to release system resources
   instream.close();

  

Version:

0.01, 1 June 2001

See Also:

OWFile, OWFileDescriptor, OWFileOutputStream

Constructor Summary

OWFileInputStream(OneWireContainer[] owd, String name)
Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the Filesystem.

OWFileInputStream(OneWireContainer owd, String name)
Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the Filesystem.

OWFileInputStream(OWFile file)
Creates a OWFileInputStream by opening a connection to an actual file, the file named by the File object file in the Filesystem.

OWFileInputStream(OWFileDescriptor fdObj)
Creates a OWFileInputStream by using the file descriptor fdObj, which represents an existing connection to an actual file in the Filesystem.

Method Summary

int	available() Returns the number of bytes that can be read from this file input stream without blocking.
void	close() Closes this file input stream and releases any system resources associated with the stream.
void	finalize() Ensures that the close method of this file input stream is called when there are no more references to it.
OWFileDescriptor	getFD() Returns the OWFileDescriptor object that represents the connection to the actual file in the Filesystem being used by this FileInputStream.
void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the mark and reset methods.
int	read() Reads a byte of data from this input stream.
int	read(byte[] b) Reads up to b.length bytes of data from this input stream into an array of bytes.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from this input stream into an array of bytes.
void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n) Skips over and discards n bytes of data from the input stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

OWFileInputStream

public OWFileInputStream(OneWireContainer owd,
                         String name)
                  throws FileNotFoundException

Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the Filesystem. A new OWFileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkRead method is called with the name argument as its argument.

If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then a FileNotFoundException is thrown.

Parameters:

owd - OneWireContainer that this Filesystem resides on

name - the system-dependent file name.

Throws:

FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

OWFileInputStream

public OWFileInputStream(OneWireContainer[] owd,
                         String name)
                  throws FileNotFoundException

Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the Filesystem. A new OWFileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkRead method is called with the name argument as its argument.

If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then a FileNotFoundException is thrown.

Parameters:

owd - array of OneWireContainers that this Filesystem resides on

name - the system-dependent file name.

Throws:

FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

OWFileInputStream

public OWFileInputStream(OWFile file)
                  throws FileNotFoundException

Creates a OWFileInputStream by opening a connection to an actual file, the file named by the File object file in the Filesystem. A new OWFileDescriptor object is created to represent this file connection.

If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then a FileNotFoundException is thrown.

Parameters:

file - the file to be opened for reading.

Throws:

FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

See Also:

OWFile.getPath()

OWFileInputStream

public OWFileInputStream(OWFileDescriptor fdObj)

Creates a OWFileInputStream by using the file descriptor fdObj, which represents an existing connection to an actual file in the Filesystem.

If fdObj is null then a NullPointerException is thrown.

Parameters:

fdObj - the file descriptor to be opened for reading.

Method Detail

read

public int read()
         throws IOException

Reads a byte of data from this input stream. This method blocks if no input is yet available.

Overrides:

read in class InputStream

Returns:

the next byte of data, or -1 if the end of the file is reached.

Throws:

IOException - if an I/O error occurs.

read

public int read(byte[] b)
         throws IOException

Reads up to b.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

IOException - if an I/O error occurs.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Reads up to len bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

IOException - if an I/O error occurs.

skip

public long skip(long n)
          throws IOException

Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.

Overrides:

skip in class InputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.

available

public int available()
              throws IOException

Returns the number of bytes that can be read from this file input stream without blocking.

Overrides:

available in class InputStream

Returns:

the number of bytes that can be read from this file input stream without blocking.

Throws:

IOException - if an I/O error occurs.

close

public void close()
           throws IOException

Closes this file input stream and releases any system resources associated with the stream.

Overrides:

close in class InputStream

Throws:

IOException - if an I/O error occurs.

getFD

public final OWFileDescriptor getFD()
                             throws IOException

Returns the OWFileDescriptor object that represents the connection to the actual file in the Filesystem being used by this FileInputStream.

Returns:

the file descriptor object associated with this stream.

Throws:

IOException - if an I/O error occurs.

See Also:

OWFileDescriptor

finalize

public void finalize()
              throws IOException

Ensures that the close method of this file input stream is called when there are no more references to it.

Throws:

IOException - if an I/O error occurs.

See Also:

close()

mark

public void mark(int readlimit)

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called.

The mark method of InputStream does nothing.

Overrides:

mark in class InputStream

Parameters:

readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also:

InputStream.reset()

reset

public void reset()
           throws IOException

Repositions this stream to the position at the time the mark method was last called on this input stream.

The general contract of reset is:

• If the method markSupported returns true, then:
  • If the method mark has not been called since the stream was created, or the number of bytes read from the stream since mark was last called is larger than the argument to mark at that last call, then an IOException might be thrown.
  • If such an IOException is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call to mark (or since the start of the file, if mark has not been called) will be resupplied to subsequent callers of the read method, followed by any bytes that otherwise would have been the next input data as of the time of the call to reset.
• If the method markSupported returns false, then:
  • The call to reset may throw an IOException.
  • If an IOException is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of the read method depend on the particular type of the input stream.

The method reset for class InputStream does nothing and always throws an IOException.

Overrides:

reset in class InputStream

Throws:

IOException - if this stream has not been marked or if the mark has been invalidated.

See Also:

InputStream.mark(int), IOException

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. The markSupported method of InputStream returns false.

Overrides:

markSupported in class InputStream

Returns:

true if this true type supports the mark and reset method; false otherwise.

See Also:

InputStream.mark(int), InputStream.reset()