Class java.io.FileInputStream - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

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Class java.io.FileInputStream

java.lang.Object
   |
   +----java.io.InputStream
           |
           +----java.io.FileInputStream

public class FileInputStream
extends InputStream

A file input stream is an input stream for reading data from a File or from a FileDescriptor.

See Also:: File, FileDescriptor, FileOutputStream

FileInputStream(File): Creates an input file stream to read from the specified File object.
FileInputStream(FileDescriptor): Creates an input file stream to read from the specified file descriptor.
FileInputStream(String): Creates an input file stream to read from a file with the specified name.

available(): Returns the number of bytes that can be read from this file input stream without blocking.
close(): Closes this file input stream and releases any system resources associated with the stream.
finalize(): Ensures that the close method of this file input stream is called when there are no more references to it.
getFD(): Returns the opaque file descriptor object associated with this stream.
read(): Reads a byte of data from this input stream.
read(byte[]): Reads up to b.length bytes of data from this input stream into an array of bytes.
read(byte[], int, int): Reads up to len bytes of data from this input stream into an array of bytes.
skip(long): Skips over and discards n bytes of data from the input stream.

FileInputStream

 public FileInputStream(String name) throws FileNotFoundException

Creates an input file stream to read from a file with the specified name.

Parameters:: name - the system-dependent file name.
Throws: FileNotFoundException: if the file is not found.
Throws: SecurityException: if a security manager exists, its checkRead method is called with the name argument to see if the application is allowed read access to the file.
See Also:: checkRead

FileInputStream

 public FileInputStream(File file) throws FileNotFoundException

Creates an input file stream to read from the specified File object.

Parameters:: file - the file to be opened for reading.
Throws: FileNotFoundException: if the file is not found.
Throws: SecurityException: if a security manager exists, its checkRead method is called with the pathname of this File argument to see if the application is allowed read access to the file.
See Also:: getPath, checkRead

FileInputStream

 public FileInputStream(FileDescriptor fdObj)

Creates an input file stream to read from the specified file descriptor.

Parameters:: fdObj - the file descriptor to be opened for reading.
Throws: SecurityException: if a security manager exists, its checkRead method is called with the file descriptor to see if the application is allowed to read from the specified file descriptor.
See Also:: checkRead

read

 public native int read() throws IOException

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

Returns:: the next byte of data, or -1 if the end of the file is reached.
Throws: IOException: if an I/O error occurs.
Overrides:: read in class InputStream

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.

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.
Overrides:: read in class InputStream

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.

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.
Overrides:: read in class InputStream

skip

 public native 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.

Parameters:: n - the number of bytes to be skipped.
Returns:: the actual number of bytes skipped.
Throws: IOException: if an I/O error occurs.
Overrides:: skip in class InputStream

available

 public native int available() throws IOException

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

Returns:: the number of bytes that can be read from this file input stream without blocking.
Throws: IOException: if an I/O error occurs.
Overrides:: available in class InputStream

close

 public native void close() throws IOException

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

Throws: IOException: if an I/O error occurs.
Overrides:: close in class InputStream

getFD

 public final FileDescriptor getFD() throws IOException

Returns the opaque file descriptor object associated with this stream.

Returns:: the file descriptor object associated with this stream.
Throws: IOException: if an I/O error occurs.
See Also:: FileDescriptor

finalize

 protected 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.
Overrides:: finalize in class Object
See Also:: close

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