org.snmp4j.smi

Class VariantVariable

java.lang.Object

org.snmp4j.smi.AbstractVariable

org.snmp4j.smi.VariantVariable

All Implemented Interfaces:

Serializable, Cloneable, Comparable<Variable>, BERSerializable, AssignableFromByteArray, AssignableFromInteger, AssignableFromLong, AssignableFromString, Variable

public class VariantVariable
extends AbstractVariable
implements AssignableFromInteger, AssignableFromLong, AssignableFromString, AssignableFromByteArray

The VariantVariable provides a decorator for any type of Variable instance, to be able to intercept or monitor variable value modification by using a VariantVariableCallback.

This class will work for implementations that use getSyntax() method to determine the variables syntax. However "instanceof" will not work.

In contrast to the native Variable implementations, VariantVariable can be modified dynamically (i.e. while a PDU is being BER encoded where this variable has been added to) without causing BER encoding errors.

Since:

1.7

Version:

1.8

Author:

Frank Fock

See Also:

Serialized Form

Field Summary

Fields inherited from class org.snmp4j.smi.AbstractVariable

SMISYNTAXES_PROPERTIES

Constructor Summary

Constructors

Constructor and Description
VariantVariable(Variable initialVariable) Creates a variant variable wrapping the specified value.
VariantVariable(Variable initialVariable, VariantVariableCallback callback) Creates a variant variable wrapping the specified value and a callback that monitors value modifications.

Method Summary

Methods

Modifier and Type	Method and Description
Object	clone() Clones this variable.
int	compareTo(Variable o)
void	decodeBER(BERInputStream inputStream) Decodes a Variable from an InputStream.
void	encodeBER(OutputStream outputStream) Encodes a Variable to an OutputStream.
boolean	equals(Object o)
void	fromSubIndex(OID subIndex, boolean impliedLength) Sets the value of this Variable from the supplied (sub-)index.
int	getBERLength() Returns the length of this Variable in bytes when encoded according to the Basic Encoding Rules (BER).
int	getSyntax() Gets the ASN.1 syntax identifier value of this SNMP variable.
Variable	getVariable() Returns the typed variable that holds the wrapped value.
int	hashCode()
boolean	isDynamic() Indicates whether this variable is dynamic, which means that it might change its value while it is being (BER) serialized.
void	setValue(byte[] value) Sets the value of this object from the supplied byte array.
void	setValue(int value)
void	setValue(long value)
void	setValue(OctetString value)
void	setValue(String value)
byte[]	toByteArray() Returns the value of this object as a byte array.
int	toInt() Returns an integer representation of this variable if such a representation exists.
long	toLong() Returns a long representation of this variable if such a representation exists.
String	toString() Gets a string representation of the variable.
OID	toSubIndex(boolean impliedLength) Converts the value of this Variable to a (sub-)index value.
protected void	updateVariable()
protected void	variableUpdated()

Methods inherited from class org.snmp4j.smi.AbstractVariable

createFromBER, createFromSyntax, equal, getBERPayloadLength, getSyntaxFromString, getSyntaxString, getSyntaxString, isException

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

VariantVariable

public VariantVariable(Variable initialVariable)

Creates a variant variable wrapping the specified value.

Parameters:

initialVariable - a Variable.

VariantVariable

public VariantVariable(Variable initialVariable,
               VariantVariableCallback callback)

Creates a variant variable wrapping the specified value and a callback that monitors value modifications.

Parameters:

initialVariable - a Variable.

callback - a callback handler that is called before the value is to be modified and after it has been modified.

Method Detail

compareTo

public int compareTo(Variable o)

Specified by:

compareTo in interface Comparable<Variable>

Specified by:

compareTo in interface Variable

Specified by:

compareTo in class AbstractVariable

updateVariable

protected void updateVariable()

variableUpdated

protected void variableUpdated()

decodeBER

public void decodeBER(BERInputStream inputStream)
               throws IOException

Description copied from class: AbstractVariable

Decodes a Variable from an InputStream.

Specified by:

decodeBER in interface BERSerializable

Specified by:

decodeBER in class AbstractVariable

Parameters:

inputStream - an InputStream containing a BER encoded byte stream.

Throws:

IOException - if the stream could not be decoded by using BER rules.

encodeBER

public void encodeBER(OutputStream outputStream)
               throws IOException

Description copied from class: AbstractVariable

Encodes a Variable to an OutputStream.

Specified by:

encodeBER in interface BERSerializable

Specified by:

encodeBER in class AbstractVariable

Parameters:

outputStream - an OutputStream.

Throws:

IOException - if an error occurs while writing to the stream.

fromSubIndex

public void fromSubIndex(OID subIndex,
                boolean impliedLength)

Description copied from class: AbstractVariable

Sets the value of this Variable from the supplied (sub-)index.

Specified by:

fromSubIndex in interface Variable

Specified by:

fromSubIndex in class AbstractVariable

Parameters:

subIndex - the sub-index OID.

impliedLength - specifies if the sub-index has an implied length. This parameter applies to variable length variables only (e.g. OctetString and OID). For other variables it has no effect.

getBERLength

public int getBERLength()

Description copied from class: AbstractVariable

Returns the length of this Variable in bytes when encoded according to the Basic Encoding Rules (BER).

Specified by:

getBERLength in interface BERSerializable

Specified by:

getBERLength in class AbstractVariable

Returns:

the BER encoded length of this variable.

getSyntax

public int getSyntax()

Description copied from class: AbstractVariable

Gets the ASN.1 syntax identifier value of this SNMP variable.

Specified by:

getSyntax in interface Variable

Specified by:

getSyntax in class AbstractVariable

Returns:

an integer value < 128 for regular SMI objects and a value >= 128 for exception values like noSuchObject, noSuchInstance, and endOfMibView.

toInt

public int toInt()

Description copied from class: AbstractVariable

Returns an integer representation of this variable if such a representation exists.

Specified by:

toInt in interface AssignableFromInteger

Specified by:

toInt in interface Variable

Specified by:

toInt in class AbstractVariable

Returns:

an integer value (if the native representation of this variable would be a long, then the long value will be casted to int).

toLong

public long toLong()

Description copied from class: AbstractVariable

Returns a long representation of this variable if such a representation exists.

Specified by:

toLong in interface AssignableFromLong

Specified by:

toLong in interface Variable

Specified by:

toLong in class AbstractVariable

Returns:

a long value.

toByteArray

public byte[] toByteArray()

Description copied from interface: AssignableFromByteArray

Returns the value of this object as a byte array.

Specified by:

toByteArray in interface AssignableFromByteArray

Returns:

a byte array.

toSubIndex

public OID toSubIndex(boolean impliedLength)

Description copied from class: AbstractVariable

Converts the value of this Variable to a (sub-)index value.

Specified by:

toSubIndex in interface Variable

Specified by:

toSubIndex in class AbstractVariable

Parameters:

impliedLength - specifies if the sub-index has an implied length. This parameter applies to variable length variables only (e.g. OctetString and OID). For other variables it has no effect.

Returns:

an OID that represents this value as an (sub-)index.

equals

public boolean equals(Object o)

Specified by:

equals in interface Variable

Specified by:

equals in class AbstractVariable

hashCode

public int hashCode()

Specified by:

hashCode in interface Variable

Specified by:

hashCode in class AbstractVariable

toString

public String toString()

Description copied from class: AbstractVariable

Gets a string representation of the variable.

Specified by:

toString in interface Variable

Specified by:

toString in class AbstractVariable

Returns:

a string representation of the variable's value.

clone

public Object clone()

Description copied from interface: Variable

Clones this variable. Cloning can be used by the SNMP4J API to better support concurrency by creating a clone for internal processing. The content of this object is independent to the content of the clone. Thus, changes to the clone will have no effect to this object.

Specified by:

clone in interface Variable

Specified by:

clone in class AbstractVariable

Returns:

a new instance of this Variable with the same value.

setValue

public void setValue(int value)

Specified by:

setValue in interface AssignableFromInteger

setValue

public void setValue(long value)

Specified by:

setValue in interface AssignableFromLong

setValue

public void setValue(OctetString value)

setValue

public void setValue(byte[] value)

Description copied from interface: AssignableFromByteArray

Sets the value of this object from the supplied byte array.

Specified by:

setValue in interface AssignableFromByteArray

Parameters:

value - a byte array.

setValue

public void setValue(String value)

Specified by:

setValue in interface AssignableFromString

getVariable

public Variable getVariable()

Returns the typed variable that holds the wrapped value.

Returns:

a Variable instance.

isDynamic

public boolean isDynamic()

Description copied from class: AbstractVariable

Indicates whether this variable is dynamic, which means that it might change its value while it is being (BER) serialized. If a variable is dynamic, it will be cloned on-the-fly when it is added to a PDU with PDU.add(VariableBinding). By cloning the value, it is ensured that there are no inconsistent changes between determining the length with AbstractVariable.getBERLength() for encoding enclosing SEQUENCES and the actual encoding of the Variable itself with AbstractVariable.encodeBER(java.io.OutputStream).

Specified by:

isDynamic in interface Variable

Overrides:

isDynamic in class AbstractVariable

Returns:

false by default. Derived classes may override this if implementing dynamic Variable instances.