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| java.lang.Object
 java.io.InputStream
java.io.FileInputStream
| FileInputStream | | public class FileInputStream extends InputStream (Code) | | A FileInputStream obtains input bytes
from a file in a file system. What files
are available depends on the host environment.
FileInputStream is meant for reading streams of raw bytes
such as image data. For reading streams of characters, consider using
FileReader.
author:
Arthur van Hoff
version:
1.78, 06/13/07
See Also: java.io.File
See Also: java.io.FileDescriptor
See Also: java.io.FileOutputStream
since:
JDK1.0
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| Constructor Summary | |
| public | FileInputStream(String name)
Creates a FileInputStream by
opening a connection to an actual file,
the file named by the path name name
in the file system. | | public | FileInputStream(File file)
Creates a FileInputStream by
opening a connection to an actual file,
the file named by the File
object file in the file system. | | public | FileInputStream(FileDescriptor fdObj)
Creates a FileInputStream by using the file descriptor
fdObj, which represents an existing connection to an
actual file in the file system.
If there is a security manager, its checkRead method is
called with the file descriptor fdObj as its argument to
see if it's ok to read the file descriptor. |
| Method Summary | |
| native public int | available()
Returns an estimate of the number of remaining bytes that can be read (or
skipped over) from this input stream without blocking by the next
invocation of a method for this input stream. | | public void | close()
Closes this file input stream and releases any system resources
associated with the stream. | | protected void | finalize()
Ensures that the close method of this file input stream is
called when there are no more references to it. | | public FileChannel | getChannel()
Returns the unique
java.nio.channels.FileChannel FileChannel object associated with this file input stream.
The initial
java.nio.channels.FileChannel.positionposition of the returned channel will be equal to the
number of bytes read from the file so far. | | final public FileDescriptor | getFD()
Returns the FileDescriptor
object that represents the connection to
the actual file in the file system being
used by this FileInputStream. | | native public int | read()
Reads a byte of data from this input stream. | | public int | read(byte b)
Reads up to b.length bytes of data from this input
stream into an array of bytes. | | public int | read(byte b, int off, int len)
Reads up to len bytes of data from this input stream
into an array of bytes. | | native public long | skip(long n)
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. |
| FileInputStream | | public FileInputStream(String name) throws FileNotFoundException(Code) | | Creates a FileInputStream by
opening a connection to an actual file,
the file named by the path name name
in the file system. A new FileDescriptor
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:
name - the system-dependent file name.
exception:
FileNotFoundException - if the file does not exist,is a directory rather than a regular file,or for some other reason cannot be opened forreading.
exception:
SecurityException - if a security manager exists and itscheckRead method denies read accessto the file.
See Also: java.lang.SecurityManager.checkRead(java.lang.String) |
| FileInputStream | | public FileInputStream(File file) throws FileNotFoundException(Code) | | Creates a FileInputStream by
opening a connection to an actual file,
the file named by the File
object file in the file system.
A new FileDescriptor object
is created to represent this file connection.
First, if there is a security manager,
its checkRead method is called
with the path represented by the file
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:
file - the file to be opened for reading.
exception:
FileNotFoundException - if the file does not exist,is a directory rather than a regular file,or for some other reason cannot be opened forreading.
exception:
SecurityException - if a security manager exists and itscheckRead method denies read access to the file.
See Also: java.io.File.getPath
See Also: java.lang.SecurityManager.checkRead(java.lang.String) |
| FileInputStream | | public FileInputStream(FileDescriptor fdObj)(Code) | | Creates a FileInputStream by using the file descriptor
fdObj, which represents an existing connection to an
actual file in the file system.
If there is a security manager, its checkRead method is
called with the file descriptor fdObj as its argument to
see if it's ok to read the file descriptor. If read access is denied
to the file descriptor a SecurityException is thrown.
If fdObj is null then a NullPointerException
is thrown.
This constructor does not throw an exception if fdObj
is {link java.io.FileDescriptor#valid() invalid}.
However, if the methods are invoked on the resulting stream to attempt
I/O on the stream, an IOException is thrown.
Parameters:
fdObj - the file descriptor to be opened for reading.
throws:
SecurityException - if a security manager exists and itscheckRead method denies read access to thefile descriptor.
See Also: SecurityManager.checkRead(java.io.FileDescriptor) |
| available | | native public int available() throws IOException(Code) | | Returns an estimate of the number of remaining bytes that can be read (or
skipped over) from this input stream without blocking by the next
invocation of a method for this input stream. The next invocation might be
the same thread or another thread. A single read or skip of this
many bytes will not block, but may read or skip fewer bytes.
In some cases, a non-blocking read (or skip) may appear to be
blocked when it is merely slow, for example when reading large
files over slow networks.
an estimate of the number of remaining bytes that can be read(or skipped over) from this input stream without blocking.
exception:
IOException - if this file input stream has been closed by calling close or an I/O error occurs. |
| close | | public void close() throws IOException(Code) | | Closes this file input stream and releases any system resources
associated with the stream.
If this stream has an associated channel then the channel is closed
as well.
exception:
IOException - if an I/O error occurs. |
| getChannel | | public FileChannel getChannel()(Code) | | Returns the unique
java.nio.channels.FileChannel FileChannel object associated with this file input stream.
The initial
java.nio.channels.FileChannel.positionposition of the returned channel will be equal to the
number of bytes read from the file so far. Reading bytes from this
stream will increment the channel's position. Changing the channel's
position, either explicitly or by reading, will change this stream's
file position.
the file channel associated with this file input stream
since:
1.4 |
| getFD | | final public FileDescriptor getFD() throws IOException(Code) | | Returns the FileDescriptor
object that represents the connection to
the actual file in the file system being
used by this FileInputStream.
the file descriptor object associated with this stream.
exception:
IOException - if an I/O error occurs.
See Also: java.io.FileDescriptor |
| read | | native public int read() throws IOException(Code) | | Reads a byte of data from this input stream. This method blocks
if no input is yet available.
the next byte of data, or -1 if the end of thefile is reached.
exception:
IOException - if an I/O error occurs. |
| read | | public int read(byte b) throws IOException(Code) | | 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.
Parameters:
b - the buffer into which the data is read. the total number of bytes read into the buffer, or-1 if there is no more data because the end ofthe file has been reached.
exception:
IOException - if an I/O error occurs. |
| read | | public int read(byte b, int off, int len) throws IOException(Code) | | Reads up to len bytes of data from this input stream
into an array of bytes. If len is not zero, the method
blocks until some input is available; otherwise, no
bytes are read and 0 is returned.
Parameters:
b - the buffer into which the data is read.
Parameters:
off - the start offset in the destination array b
Parameters:
len - the maximum number of bytes read. the total number of bytes read into the buffer, or-1 if there is no more data because the end ofthe file has been reached.
exception:
NullPointerException - If b is null.
exception:
IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
exception:
IOException - if an I/O error occurs. |
| skip | | native public long skip(long n) throws IOException(Code) | | 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. If n is negative, an
IOException is thrown, even though the skip
method of the
InputStream superclass does nothing in this case.
The actual number of bytes skipped is returned.
This method may skip more bytes than are remaining in the backing
file. This produces no exception and the number of bytes skipped
may include some number of bytes that were beyond the EOF of the
backing file. Attempting to read from the stream after skipping past
the end will result in -1 indicating the end of the file.
Parameters:
n - the number of bytes to be skipped. the actual number of bytes skipped.
exception:
IOException - if n is negative, if the stream does notsupport seek, or if an I/O error occurs. |
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