com.norconex.commons.lang.io

Class IOUtil

java.lang.Object

com.norconex.commons.lang.io.IOUtil

public final class IOUtil
extends Object

I/O related utility methods.

Author:

Pascal Essiembre

Method Summary

Modifier and Type	Method and Description
static byte[]	borrowBytes(InputStream is, int qty) Gets and resets the specified number of bytes from the input stream.
static String[]	head(InputStream is, Charset encoding, int lineQty) Gets the first lines from an input stream, using the specified encoding.
static String[]	head(InputStream is, int lineQty) Gets the first lines from an input stream, using UTF-8.
static String[]	head(InputStream is, String encoding, int lineQty) Gets the first lines from an input stream, using the specified encoding.
static boolean	startsWith(InputStream is, byte[] bytes) Whether the given input stream starts the specified bytes array or not.
static String[]	tail(InputStream is, Charset encoding, int lineQty) Gets the last lines from an input stream, using the specified encoding.
static String[]	tail(InputStream is, int lineQty) Gets the last lines from an input stream, using UTF-8.
static String[]	tail(InputStream is, String encoding, int lineQty) Gets the last lines from an input stream, using the specified encoding.
static BufferedInputStream	toBufferedInputStream(InputStream in) Wraps the input stream in a BufferedInputStream if not a subclass already.
static BufferedReader	toBufferedReader(Reader reader) Wraps the reader in a BufferedReader if not a subclass already.

Methods inherited from class java.lang.Object

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

Method Detail

startsWith

public static boolean startsWith(InputStream is,
                                 byte[] bytes)
                          throws IOException

Whether the given input stream starts the specified bytes array or not. The input stream must support marking. If the byte array or the input stream is null, then false is returned.

Parameters:

is - input stream

bytes - byte array to compare

Returns:

true if input stream starts with byte array

Throws:

IOException - if InputStream.markSupported() returns false

borrowBytes

public static byte[] borrowBytes(InputStream is,
                                 int qty)
                          throws IOException

Gets and resets the specified number of bytes from the input stream.

Parameters:

is - input stream

qty - number of bytes to read

Returns:

byte array of length matching the quantity requested

Throws:

IOException - if InputStream.markSupported() returns false

toBufferedReader

public static BufferedReader toBufferedReader(Reader reader)

Wraps the reader in a BufferedReader if not a subclass already.

Parameters:

reader - the reader to wrap if needed

Returns:

buffered reader

Since:

1.6.0

toBufferedInputStream

public static BufferedInputStream toBufferedInputStream(InputStream in)

Wraps the input stream in a BufferedInputStream if not a subclass already.

Parameters:

in - the input stream to wrap if needed

Returns:

buffered input stream

Since:

1.6.0

tail

public static String[] tail(InputStream is,
                            int lineQty)
                     throws IOException

Gets the last lines from an input stream, using UTF-8. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

Use of this method can often be a bad idea (especially on large streams) since it needs to read the entire stream to return the last lines. If you are dealing with files, use FileUtil.tail( java.io.File, int) instead, which can read a file starting from the end.

Parameters:

is - input stream

lineQty - maximum number of lines to return

Returns:

lines as a string array

Throws:

IOException - problem reading lines

tail

public static String[] tail(InputStream is,
                            String encoding,
                            int lineQty)
                     throws IOException

Gets the last lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

Use of this method can often be a bad idea (especially on large streams) since it needs to read the entire stream to return the last lines. If you are dealing with files, use FileUtil.tail( File, String, int) instead, which can read a file starting from the end.

Parameters:

is - input stream

encoding - character encoding

lineQty - maximum number of lines to return

Returns:

lines as a string array

Throws:

IOException - problem reading lines

Since:

1.5.0

tail

public static String[] tail(InputStream is,
                            Charset encoding,
                            int lineQty)
                     throws IOException

Gets the last lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

Use of this method can often be a bad idea (especially on large streams) since it needs to read the entire stream to return the last lines. If you are dealing with files, use FileUtil.tail( File, String, int) instead, which can read a file starting from the end.

Parameters:

is - input stream

encoding - character encoding

lineQty - maximum number of lines to return

Returns:

lines as a string array

Throws:

IOException - problem reading lines

Since:

1.14.0

head

public static String[] head(InputStream is,
                            int lineQty)
                     throws IOException

Gets the first lines from an input stream, using UTF-8. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

Parameters:

is - input stream

lineQty - maximum number of lines to return

Returns:

lines as a string array

Throws:

IOException - problem reading lines

head

public static String[] head(InputStream is,
                            String encoding,
                            int lineQty)
                     throws IOException

Gets the first lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

Parameters:

is - input stream

encoding - character encoding

lineQty - maximum number of lines to return

Returns:

lines as a string array

Throws:

IOException - problem reading lines

head

public static String[] head(InputStream is,
                            Charset encoding,
                            int lineQty)
                     throws IOException

Gets the first lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

Parameters:

is - input stream

encoding - character encoding

lineQty - maximum number of lines to return

Returns:

lines as a string array

Throws:

IOException - problem reading lines

Since:

1.14.0