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JavaTM 2 Platform Standard Ed. 5.0 |
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java.lang.Object extended by java.io.InputStream extended by java.io.FileInputStream
public class FileInputStream
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.
File,
FileDescriptor,
FileOutputStream
| Constructor Summary | |
|---|---|
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. |
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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. |
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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. |
|
| 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. |
protected void |
finalize()
Ensures that the close method of this file input stream is
called when there are no more references to it. |
FileChannel |
getChannel()
Returns the unique FileChannel
object associated with this file input stream. |
FileDescriptor |
getFD()
Returns the FileDescriptor
object that represents the connection to
the actual file in the file system being
used by this FileInputStream. |
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. |
long |
skip(long n)
Skips over and discards n bytes of data from the
input stream. |
| Methods inherited from class java.io.InputStream |
|---|
mark, markSupported, reset |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public FileInputStream(String name) throws FileNotFoundException
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.
name - the system-dependent file name.
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.
SecurityException - if a security manager exists and its
checkRead method denies read access
to the file.SecurityManager.checkRead(java.lang.String)public FileInputStream(File file) throws FileNotFoundException
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.
file - the file to be opened for reading.
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.
SecurityException - if a security manager exists and its
checkRead method denies read access to the file.File.getPath(),
SecurityManager.checkRead(java.lang.String)public FileInputStream(FileDescriptor fdObj)
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.
fdObj - the file descriptor to be opened for reading.
SecurityException - if a security manager exists and its
checkRead method denies read access to the
file descriptor.SecurityManager.checkRead(java.io.FileDescriptor)| Method Detail |
|---|
public int read() throws IOException
read in class InputStream-1 if the end of the
file is reached.
IOException - if an I/O error occurs.public int read(byte[] b) throws IOException
b.length bytes of data from this input
stream into an array of bytes. This method blocks until some input
is available.
read in class InputStreamb - the buffer into which the data is read.
-1 if there is no more data because the end of
the file has been reached.
IOException - if an I/O error occurs.InputStream.read(byte[], int, int)public int read(byte[] b, int off, int len) throws IOException
len bytes of data from this input stream
into an array of bytes. This method blocks until some input is
available.
read in class InputStreamb - the buffer into which the data is read.off - the start offset of the data.len - the maximum number of bytes read.
-1 if there is no more data because the end of
the file has been reached.
IOException - if an I/O error occurs.InputStream.read()public long skip(long n) throws IOException
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.
skip in class InputStreamn - the number of bytes to be skipped.
IOException - if n is negative, or if an I/O error occurs.public int available() throws IOException
available in class InputStreamIOException - if an I/O error occurs.public void close() throws IOException
If this stream has an associated channel then the channel is closed as well.
close in interface Closeableclose in class InputStreamIOException - if an I/O error occurs.public final FileDescriptor getFD() throws IOException
FileDescriptor
object that represents the connection to
the actual file in the file system being
used by this FileInputStream.
IOException - if an I/O error occurs.FileDescriptorpublic FileChannel getChannel()
FileChannel
object associated with this file input stream.
The initial position 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.
protected void finalize() throws IOException
close method of this file input stream is
called when there are no more references to it.
IOException - if an I/O error occurs.close()
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JavaTM 2 Platform Standard Ed. 5.0 |
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