java.lang.Object
org.snmp4j.smi.AbstractVariable
- All Implemented Interfaces:
Serializable
,Cloneable
,Comparable<Variable>
,BERSerializable
,Variable
- Direct Known Subclasses:
Counter64
,Integer32
,Null
,OctetString
,OID
,SMIAddress
,UnsignedInteger32
,VariantVariable
The
Variable
abstract class is the base class for all SNMP
variables.
All derived classes need to be registered with their SMI BER type in the
smisyntaxes.properties
so that the
createFromBER(BERInputStream inputStream)
method
is able to decode a variable from a BER encoded stream.
To register additional syntaxes, set the system property
SMISYNTAXES_PROPERTIES
before decoding a Variable for the first
time. The path of the property file must be accessible from the classpath
and it has to be specified relative to the Variable
class.
- Since:
- 1.8
- Version:
- 1.8
- Author:
- Frank Fock, Jochen Katz
- See Also:
-
Field Summary
-
Constructor Summary
ConstructorDescriptionThe abstractVariable
class serves as the base class for all specific SNMP syntax types. -
Method Summary
Modifier and TypeMethodDescriptionabstract Object
clone()
Clones this variable.abstract int
static Variable
createFromBER
(BERInputStream inputStream) Creates aVariable
from a BER encodedBERInputStream
.static Variable
createFromSyntax
(int smiSyntax) Creates aVariable
from the supplied SMI syntax identifier.abstract void
decodeBER
(BERInputStream inputStream) Decodes aVariable
from anBERInputStream
.abstract void
encodeBER
(OutputStream outputStream) Encodes aVariable
to anOutputStream
.static boolean
Tests if two variables have the same value.abstract boolean
abstract void
fromSubIndex
(OID subIndex, boolean impliedLength) Sets the value of thisVariable
from the supplied (sub-)index.abstract int
Returns the length of thisVariable
in bytes when encoded according to the Basic Encoding Rules (BER).int
Returns the length of the payload of thisBERSerializable
object in bytes when encoded according to the Basic Encoding Rules (BER).abstract int
Gets the ASN.1 syntax identifier value of this SNMP variable.static int
getSyntaxFromString
(String syntaxString) Returns the BER syntax ID for the supplied syntax string (as returned bygetSyntaxString(int)
).final String
Gets a textual description of this Variable.static String
getSyntaxString
(int syntax) Gets a textual description of the supplied syntax type.abstract int
hashCode()
boolean
Indicates whether this variable is dynamic, which means that it might change its value while it is being (BER) serialized.boolean
Checks whether this variable represents an exception like noSuchObject, noSuchInstance, and endOfMibView.abstract int
toInt()
Returns an integer representation of this variable if such a representation exists.abstract long
toLong()
Returns a long representation of this variable if such a representation exists.abstract String
toString()
Gets a string representation of the variable.abstract OID
toSubIndex
(boolean impliedLength) Converts the value of thisVariable
to a (sub-)index value.
-
Field Details
-
SMISYNTAXES_PROPERTIES
- See Also:
-
-
Constructor Details
-
AbstractVariable
public AbstractVariable()The abstractVariable
class serves as the base class for all specific SNMP syntax types.
-
-
Method Details
-
equals
-
compareTo
- Specified by:
compareTo
in interfaceComparable<Variable>
- Specified by:
compareTo
in interfaceVariable
-
hashCode
public abstract int hashCode() -
getBERLength
public abstract int getBERLength()Returns the length of thisVariable
in bytes when encoded according to the Basic Encoding Rules (BER).- Specified by:
getBERLength
in interfaceBERSerializable
- Returns:
- the BER encoded length of this variable.
-
getBERPayloadLength
public int getBERPayloadLength()Description copied from interface:BERSerializable
Returns the length of the payload of thisBERSerializable
object in bytes when encoded according to the Basic Encoding Rules (BER).- Specified by:
getBERPayloadLength
in interfaceBERSerializable
- Returns:
- the BER encoded length of this variable.
-
decodeBER
Decodes aVariable
from anBERInputStream
.- Specified by:
decodeBER
in interfaceBERSerializable
- Parameters:
inputStream
- anBERInputStream
containing a BER encoded byte stream.- Throws:
IOException
- if the stream could not be decoded by using BER rules.
-
encodeBER
Encodes aVariable
to anOutputStream
.- Specified by:
encodeBER
in interfaceBERSerializable
- Parameters:
outputStream
- anOutputStream
.- Throws:
IOException
- if an error occurs while writing to the stream.
-
createFromBER
Creates aVariable
from a BER encodedBERInputStream
. Subclasses ofVariable
are registered using the properties filesmisyntaxes.properties
in this package. The properties are read when this method is called first.- Parameters:
inputStream
- anBERInputStream
containing a BER encoded byte stream.- Returns:
- an instance of a subclass of
Variable
. - Throws:
IOException
- if theinputStream
is not properly BER encoded.
-
createFromSyntax
Creates aVariable
from the supplied SMI syntax identifier. Subclasses ofVariable
are registered using the properties filesmisyntaxes.properties
in this package. The properties are read when this method is called for the first time.- Parameters:
smiSyntax
- an SMI syntax identifier of the registered types, which is typically defined bySMIConstants
.- Returns:
- a
Variable
variable instance of the supplied SMI syntax.
-
getSyntax
public abstract int getSyntax()Gets the ASN.1 syntax identifier value of this SNMP variable. -
isException
public boolean isException()Checks whether this variable represents an exception like noSuchObject, noSuchInstance, and endOfMibView.- Specified by:
isException
in interfaceVariable
- Returns:
true
if the syntax of this variable is an instance ofNull
and its syntax equals one of the following:
-
toString
Gets a string representation of the variable. -
toInt
public abstract int toInt()Returns an integer representation of this variable if such a representation exists.- Specified by:
toInt
in interfaceVariable
- Returns:
- an integer value (if the native representation of this variable would be a long, then the long value will be casted to int).
- Throws:
UnsupportedOperationException
- if an integer representation does not exists for this Variable.- Since:
- 1.7
-
toLong
public abstract long toLong()Returns a long representation of this variable if such a representation exists.- Specified by:
toLong
in interfaceVariable
- Returns:
- a long value.
- Throws:
UnsupportedOperationException
- if a long representation does not exists for this Variable.- Since:
- 1.7
-
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. -
getSyntaxString
Gets a textual description of the supplied syntax type.- Parameters:
syntax
- the BER code of the syntax.- Returns:
- a textual description like 'Integer32' for
syntax
as used in the Structure of Management Information (SMI) modules. '?' is returned if the supplied syntax is unknown.
-
getSyntaxString
Gets a textual description of this Variable.- Specified by:
getSyntaxString
in interfaceVariable
- Returns:
- a textual description like 'Integer32' as used in the Structure of Management Information (SMI) modules. '?' is returned if the syntax is unknown.
- Since:
- 1.7
-
getSyntaxFromString
Returns the BER syntax ID for the supplied syntax string (as returned bygetSyntaxString(int)
).- Parameters:
syntaxString
- the textual representation of the syntax.- Returns:
- the corresponding BER ID.
- Since:
- 1.6
-
toSubIndex
Converts the value of thisVariable
to a (sub-)index value.- Specified by:
toSubIndex
in interfaceVariable
- Parameters:
impliedLength
- specifies if the sub-index has an implied length. This parameter applies to variable length variables only (e.g.OctetString
andOID
). For other variables it has no effect.- Returns:
- an OID that represents this value as an (sub-)index.
- Throws:
UnsupportedOperationException
- if this variable cannot be used in an index.- Since:
- 1.7
-
fromSubIndex
Sets the value of thisVariable
from the supplied (sub-)index.- Specified by:
fromSubIndex
in interfaceVariable
- 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
andOID
). For other variables it has no effect.- Throws:
UnsupportedOperationException
- if this variable cannot be used in an index.- Since:
- 1.7
-
isDynamic
public boolean isDynamic()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 aPDU
withPDU.add(VariableBinding)
. By cloning the value, it is ensured that there are no inconsistent changes between determining the length withgetBERLength()
for encoding enclosing SEQUENCES and the actual encoding of the Variable itself withencodeBER(java.io.OutputStream)
. -
equal
Tests if two variables have the same value.- Parameters:
a
- a variable.b
- another variable.- Returns:
true
ifa == null) ? (b == null) : a.equals(b)
.- Since:
- 2.0
-