java.io.InputStream
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FlexDoc/Javadoc 2.0 Demo Java Doc |
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java.io.FileInputStreamFileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader.
Constructor Summary |
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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.
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Method Summary |
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int |
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.
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void |
close()
Closes this file input stream and releases any system resources
associated with the stream.
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Returns the unique FileChannel
object associated with this file input stream.
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final FileDescriptor |
getFD()
Returns the FileDescriptor
object that represents the connection to
the actual file in the file system being
used by this FileInputStream.
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int |
read()
Reads a byte of data from this input stream.
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int |
read(byte[] b)
Reads up to b.length bytes of data from this input
stream into an array of bytes.
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int |
read(byte[] b, int off, int len)
Reads up to len bytes of data from this input stream
into an array of bytes.
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byte[] |
Reads all remaining bytes from the input stream.
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byte[] |
readNBytes(int len)
Reads up to a specified number of bytes from the input stream.
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long |
skip(long n)
Skips over and discards n bytes of data from the
input stream.
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Methods inherited from class java.io.InputStream |
Methods inherited from class java.lang.Object |
public FileInputStream |
(String name) |
throws |
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.
public FileInputStream |
(File file) |
throws |
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.
public FileInputStream |
(FileDescriptor fdObj) |
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 invalid. However, if the methods are invoked on the resulting stream to attempt I/O on the stream, an IOException is thrown.
public int read |
() |
throws |
public int read |
(byte[] b) |
throws |
public int read |
(byte[] b, int off, int len) |
throws |
public byte[] readAllBytes |
() |
throws |
When this stream reaches end of stream, further invocations of this method will return an empty byte array.
Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data.
The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.
If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
public byte[] readNBytes |
(int len) |
throws |
The length of the returned array equals the number of bytes read from the stream. If len is zero, then no bytes are read and an empty byte array is returned. Otherwise, up to len bytes are read from the stream. Fewer than len bytes may be read if end of stream is encountered.
When this stream reaches end of stream, further invocations of this method will return an empty byte array.
Note that this method is intended for simple cases where it is convenient to read the specified number of bytes into a byte array. The total amount of memory allocated by this method is proportional to the number of bytes read from the stream which is bounded by len. Therefore, the method may be safely called with very large values of len provided sufficient memory is available.
The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.
If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
public long skip |
(long n) |
throws |
The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. If n is negative, the method will try to skip backwards. In case the backing file does not support backward skip at its current position, an IOException is thrown. The actual number of bytes skipped is returned. If it skips forwards, it returns a positive value. If it skips backwards, it returns a negative value.
This method may skip more bytes than what 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.
public int available |
() |
throws |
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.
public void close |
() |
throws |
If this stream has an associated channel then the channel is closed as well.
public final FileDescriptor getFD |
() |
throws |
public FileChannel getChannel |
() |
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.
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FlexDoc/Javadoc 2.0 Demo Java Doc |
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