lp.wrap
Class WrapperUtils

java.lang.Object
  lp.wrap.WrapperUtils

public class WrapperUtils
extends Object

This class provides some static methods that can be useful when handling external commands that receive data on their standard input. It provides:

• convenience methods for extracting a command name from the command string (getCommandName(String) and getShortCommandName(String)),
• methods for transfering bytes from an InputStream to an OutputStream (transfer(InputStream, OutputStream)) or to a StringBuilder (transfer(InputStream, StringBuilder))

Version:

1.0.0

Author:

Martin Slota

Field Summary

private byte[]	byteBuffer A byte buffer for the transfer(InputStream, OutputStream) method.
private char[]	charBuffer A character buffer for the transfer(InputStream, StringBuilder) method.
private static WrapperUtils	instance Reference to the singleton instance of this class.

Constructor Summary

private

WrapperUtils() A private constructor to ensure this is really a singleton.

Method Summary

String	dumpToString(InputStream from) Returns the contents of an InputStream as a string.
Process	exec(String command) Executes the command command through Runtime.exec(String) and puts the contents of input on the process's standard input.
String	getCommandName(String command) Returns the command's name given the command string, i.e. the part of the command string that precedes the first whitespace character.
static WrapperUtils	getInstance() Returns the singleton instance.
String	getShortCommandName(String command) Returns the command's name without the preceding path given the command string, i.e. the part of the command's name (as defined in getCommandName(String)) that follows the last File.separatorChar character.
void	transfer(InputStream from, OutputStream to) Transfers the contents of from to to.
StringBuilder	transfer(InputStream from, StringBuilder to) Transfers the contents of from to to using the default character encoding.
void	transfer(String from, OutputStream to) Transfers the contents of from to to using the default character encoding.

Methods inherited from class java.lang.Object

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

Field Detail

byteBuffer

private final byte[] byteBuffer

A byte buffer for the transfer(InputStream, OutputStream) method.

charBuffer

private final char[] charBuffer

A character buffer for the transfer(InputStream, StringBuilder) method.

instance

private static WrapperUtils instance

Reference to the singleton instance of this class.

Constructor Detail

WrapperUtils

private WrapperUtils()

A private constructor to ensure this is really a singleton.

Method Detail

getInstance

public static WrapperUtils getInstance()

Returns the singleton instance.

getCommandName

public String getCommandName(String command)

Returns the command's name given the command string, i.e. the part of the command string that precedes the first whitespace character. For example, if the separator character is '/' and the command is "/usr/bin/mkdir tmp", then the result will be "/usr/bin/mkdir". If command is null, then null is returned.

Parameters:

command - the command string

Returns:

the command's name

getShortCommandName

public String getShortCommandName(String command)

Returns the command's name without the preceding path given the command string, i.e. the part of the command's name (as defined in getCommandName(String)) that follows the last File.separatorChar character. For example, if the separator character is '/' and the command is "/usr/bin/mkdir tmp", then the result will be "mkdir". If command is null, then null is returned.

Parameters:

command - the command string

Returns:

the command's name

Throws:

IllegalArgumentException - if command is null.

See Also:

getCommandName(String)

transfer

public void transfer(InputStream from,
                     OutputStream to)

Transfers the contents of from to to. Invokes from.close() after the transfer. This method is thread-safe.

Parameters:

from - source of the transfer

to - destination of the transfer

Throws:

NullPointerException - if from contains some bytes and to is null (in other cases the null values don't matter)

IOException - (wrapped in an ExceptionAdapter) if an I/O error occurs during the transfer

transfer

public void transfer(String from,
                     OutputStream to)

Transfers the contents of from to to using the default character encoding. This method is thread-safe. If from is null, nothing is appended.

Parameters:

from - string convert to bytes and append to to

to - destination of the transfer

Throws:

NullPointerException - if from contains some bytes and to is null (otherwise the null values are gracefully ignored)

IOException - (wrapped in an ExceptionAdapter) if an I/O error occurs during the transfer

transfer

public StringBuilder transfer(InputStream from,
                              StringBuilder to)

Transfers the contents of from to to using the default character encoding. Invokes from.close() after the transfer. This method is thread-safe.

Parameters:

from - source of the transfer

to - destination of the transfer

Throws:

NullPointerException - if from contains some bytes and to is null (otherwise the null values are gracefully ignored)

IOException - (wrapped in an ExceptionAdapter) if an I/O error occurs during the transfer

dumpToString

public String dumpToString(InputStream from)

Returns the contents of an InputStream as a string. Uses the default encoding to convert bytes to characters. If from is null, an empty string is returned. This method is thread-safe.

Parameters:

from - the source input stream

Returns:

the string with contents of from

Throws:

IOException - (wrapped in an ExceptionAdapter) if an I/O error occurs during the conversion

exec

public Process exec(String command)
             throws WrapperException

Executes the command command through Runtime.exec(String) and puts the contents of input on the process's standard input. The created Process instance is returned.

Parameters:

command - the command to be executed

Returns:

the created Process object

Throws:

NullPointerException - if command is null

IllegalArgumentException - if command is an empty string

WrapperException - if an IOException occurs while creating the process