An OracleBlob object is an object that has a reference to BLOB data. It provides methods for performing operations on BLOBs.
Class Inheritance
Object
MarshalByRefObject
Stream
OracleBlob
Declaration
// C# public sealed class OracleBlob : Stream, ICloneable
Thread Safety
All public static methods are thread-safe, although instance methods do not guarantee thread safety.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class OracleBlobSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob = new OracleBlob(con);
// Write 4 bytes from writeBuffer, starting at buffer offset 0
byte[] writeBuffer = new byte[4] {1, 2, 3, 4};
blob.Write(writeBuffer, 0, 4);
// Append first 2 bytes from writeBuffer {1, 2} to the oracleBlob
blob.Append(writeBuffer, 0, 2);
// Prints "blob.Length = 6"
Console.WriteLine("blob.Length = " + blob.Length);
// Reset the Position for the Read
blob.Position = 0;
// Read 6 bytes into readBuffer, starting at buffer offset 0
byte[] readBuffer = new byte[6];
int bytesRead = blob.Read(readBuffer, 0, 6);
// Prints "bytesRead = 6"
Console.WriteLine("bytesRead = " + bytesRead);
// Prints "readBuffer = 123412"
Console.Write("readBuffer = ");
for(int index = 0; index < readBuffer.Length; index++)
{
Console.Write(readBuffer[index]);
}
Console.WriteLine();
// Search for the 2nd occurrence of a byte pattern '12'
// starting from byte offset 0 in the OracleBlob
byte[] pattern = new byte[2] {1, 2};
long posFound = blob.Search(pattern, 0, 2);
// Prints "posFound = 5"
Console.WriteLine("posFound = " + posFound);
// Erase 4 bytes of data starting at byte offset 1
// Sets bytes to zero
blob.Erase(1, 4);
byte[] erasedBuffer = blob.Value;
//Prints "erasedBuffer = 100002"
Console.Write("erasedBuffer = ");
for(int index = 0; index < erasedBuffer.Length; index++)
{
Console.Write(erasedBuffer[index]);
}
Console.WriteLine();
blob.Close();
blob.Dispose();
con.Close();
con.Dispose();
}
}
Requirements
Namespace: Oracle.DataAccess.Types
Assembly: Oracle.DataAccess.dll
OracleBlob members are listed in the following tables:
OracleBlob Constructors
OracleBlob constructors are listed in Table 10-10.
Table 10-10 OracleBlob Constructors
| Constructor | Description |
|---|---|
| OracleBlob Constructors | Creates an instance of the OracleBlob class (Overloaded) |
OracleBlob Static Fields
OracleBlob static fields are listed in Table 10-11.
Table 10-11 OracleBlob Static Fields
| Field | Description |
|---|---|
| MaxSize | Holds the maximum number of bytes a BLOB can hold, which is 4,294,967,295 (2^32 - 1) bytes |
OracleBlob Static Methods
OracleBlob static methods are listed in Table 10-12.
OracleBlob Instance Properties
OracleBlob instance properties are listed in Table 10-13.
Table 10-13 OracleBlob Instance Properties
| Properties | Description |
|---|---|
| CanRead | Indicates whether or not the LOB stream can be read |
| CanSeek | Indicates whether or not forward and backward seek operations be performed |
| CanWrite | Indicates whether or not the LOB object supports writing |
| Connection | Indicates the OracleConnection that is used to retrieve and write BLOB data |
| IsEmpty | Indicates whether the BLOB is empty or not |
| IsInChunkWriteMode | Indicates whether or not the BLOB has been opened to defer index updates |
| IsTemporary | Indicates whether or not the current instance is bound to a temporary BLOB |
| Length | Indicates the size of the BLOB data |
| OptimumChunkSize | Indicates the optimal data buffer length (or multiples thereof) that read and write operations should use to improve performance |
| Position | Indicates the current read or write position in the LOB stream |
| Value | Returns the data, starting from the first byte in BLOB, as a byte array |
OracleBlob Instance Methods
OracleBlob instance methods are listed in Table 10-14.
Table 10-14 OracleBlob Instance Methods
| Methods | Description |
|---|---|
| Append | Appends the supplied data to the current OracleBlob instance (Overloaded) |
| BeginChunkWrite | Opens the BLOB |
BeginRead |
Inherited from Stream |
BeginWrite |
Inherited from Stream |
| Clone | Creates a copy of an OracleBlob object |
| Close | Closes the current stream and releases any resources associated with it |
| Compare | Compares data referenced by the current instance and that of the supplied object |
| CopyTo | Copies from the current OracleBlob instance to an OracleBlob object (Overloaded) |
CreateObjRef |
Inherited from MarshalByRefObject |
| Dispose | Releases resources allocated by this object |
| EndChunkWrite | Closes the BLOB referenced by the current OracleBlob instance |
EndRead |
Inherited from Stream |
EndWrite |
Inherited from Stream |
Equals |
Inherited from Object (Overloaded) |
| Erase | Erases data (Overloaded) |
Flush |
Not supported |
GetHashCode |
Inherited from Object |
GetLifetimeService |
Inherited from MarshalByRefObject |
GetType |
Inherited from Object |
InitializedLifetimeService |
Inherited from MarshalByRefObject |
| IsEqual | Compares the LOB data referenced by the two OracleBlobs |
| Read | Reads a specified amount of bytes from the ODP.NET LOB Type instance and populates the buffer |
ReadByte |
Inherited from Stream |
| Search | Searches for a binary pattern in the current instance of an OracleBlob |
| Seek | Sets the position in the current LOB stream |
| SetLength | Trims or truncates the BLOB value to the specified length |
ToString |
Inherited from Object |
| Write | Writes the supplied buffer into the OracleBlob |
WriteByte |
Inherited from Stream |
OracleBlob constructors are listed in Table 10-10.
Overload List:
This constructor creates an instance of the OracleBlob class bound to a temporary BLOB with an OracleConnection object.
OracleBlob(OracleConnection, bool)
This constructor creates an instance of the OracleBlob class bound to a temporary BLOB with an OracleConnection object and a boolean value for caching.
This constructor creates an instance of the OracleBlob class bound to a temporary BLOB with an OracleConnection object.
Declaration
// C#
public OracleBlob(OracleConnection con);
Parameters
con
The OracleConnection object.
Exceptions
InvalidOperationException - The OracleConnection is not opened.
Remarks
The connection must be opened explicitly by the application. OracleBlob does not open the connection implicitly.
The temporary BLOB utilizes the provided connection to store BLOB data. Caching is not turned on by this constructor.
This constructor creates an instance of the OracleBlob class bound to a temporary BLOB with an OracleConnection object and a boolean value for caching.
Declaration
// C# public OracleBlob(OracleConnection con, bool bCaching);
Parameters
con
The OracleConnection object.
bCaching
A flag for enabling or disabling server-side caching.
Exceptions
InvalidOperationException - The OracleConnection is not opened.
Remarks
The connection must be opened explicitly by the application. OracleBlob does not open the connection implicitly.
The temporary BLOB uses the provided connection to store BLOB data. The bCaching input parameter determines whether or not server-side caching is used.
OracleBlob static fields are listed in Table 10-15.
Table 10-15 OracleBlob Static Fields
| Field | Description |
|---|---|
| MaxSize | Holds the maximum number of bytes a BLOB can hold, which is 4,294,967,295 (2^32 - 1) bytes |
The MaxSize field holds the maximum number of bytes a BLOB can hold, which is 4,294,967,295 (2^32 - 1) bytes.
Declaration
// C# public static readonly Int64 MaxSize = 4294967295;
Remarks
This field can be useful in code that checks whether or not the operation exceeds the maximum length allowed.
OracleBlob static methods are listed in Table 10-16.
OracleBlob instance properties are listed in Table 10-17.
Table 10-17 OracleBlob Instance Properties
| Properties | Description |
|---|---|
| CanRead | Indicates whether or not the LOB stream can be read |
| CanSeek | Indicates whether or not forward and backward seek operations be performed |
| CanWrite | Indicates whether or not the LOB object supports writing |
| Connection | Indicates the OracleConnection that is used to retrieve and write BLOB data |
| IsEmpty | Indicates whether the BLOB is empty or not |
| IsInChunkWriteMode | Indicates whether or not the BLOB has been opened to defer index updates |
| IsTemporary | Indicates whether or not the current instance is bound to a temporary BLOB |
| Length | Indicates the size of the BLOB data |
| OptimumChunkSize | Indicates the optimal data buffer length (or multiples thereof) that read and write operations should use to improve performance |
| Position | Indicates the current read or write position in the LOB stream |
| Value | Returns the data, starting from the first byte in BLOB, as a byte array |
Overrides Stream
This instance property indicates whether or not the LOB stream can be read.
Declaration
// C#
public override bool CanRead{get;}
Property Value
If the LOB stream can be read, returns true; otherwise, returns false.
Overrides Stream
This instance property indicates whether or not forward and backward seek operations can be performed.
Declaration
// C#
public override bool CanSeek{get;}
Property Value
If forward and backward seek operations can be performed, returns true; otherwise, returns false.
Overrides Stream
This instance property indicates whether or not the LOB object supports writing.
Declaration
// C#
public override bool CanWrite{get;}
Property Value
If the LOB stream can be written, returns true; otherwise, returns false.
This instance property indicates the OracleConnection that is used to retrieve and write BLOB data.
Declaration
// C#
public OracleConnection Connection {get;}
Property Value
An object of OracleConnection.
Exceptions
ObjectDisposedException - The object is already disposed.
This instance property indicates whether the BLOB is empty or not.
Declaration
// C#
public bool IsEmpty {get;}
Property Value
A bool that indicates whether or not the BLOB is empty.
Exceptions
ObjectDisposedException - The object is already disposed.
This instance property indicates whether or not the BLOB has been opened to defer index updates.
Declaration
// C#
public bool IsInChunkWriteMode{get;}
Property Value
If the BLOB has been opened, returns true; otherwise, returns false.
This instance property indicates whether or not the current instance is bound to a temporary BLOB.
Declaration
// C#
public bool IsTemporary {get;}
Property Value
bool
Overrides Stream
This instance property indicates the size of the BLOB data in bytes.
Declaration
// C#
public override Int64 Length {get;}
Property Value
A number indicating the size of the BLOB data in bytes.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
This instance property indicates the optimal data buffer length (or multiples thereof) that read and write operations should use to improve performance.
Declaration
// C#
public int OptimumChunkSize{get;}
Property Value
A number representing the minimum bytes to retrieve or send.
Exceptions
ObjectDisposedException - The object is already disposed.
Overrides Stream
This instance property indicates the current read or write position in the LOB stream.
Declaration
// C#
public override Int64 Position{get; set;}
Property Value
An Int64 that indicates the read or write position.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - The Position is less than 0.
This instance property returns the data, starting from the first byte in the BLOB, as a byte array.
Declaration
// C#
public Byte[] Value{get;}
Property Value
A byte array.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - The Value is less than 0.
Remarks
The value of Position is not used or changed by using this property. 2 GB is the maximum byte array length that can be returned by this property.
OracleBlob instance methods are listed in Table 10-18.
Table 10-18 OracleBlob Instance Methods
| Methods | Description |
|---|---|
| Append | Appends the supplied data to the current OracleBlob instance (Overloaded) |
| BeginChunkWrite | Opens the BLOB |
BeginRead |
Inherited from Stream |
BeginWrite |
Inherited from Stream |
| Clone | Creates a copy of an OracleBlob object |
| Close | Closes the current stream and releases any resources associated with it |
| Compare | Compares data referenced by the current instance and that of the supplied object |
| CopyTo | Copies from the current OracleBlob instance to an OracleBlob object (Overloaded) |
CreateObjRef |
Inherited from MarshalByRefObject |
| Dispose | Releases resources allocated by this object |
| EndChunkWrite | Closes the BLOB referenced by the current OracleBlob instance |
EndRead |
Inherited from Stream |
EndWrite |
Inherited from Stream |
Equals |
Inherited from Object (Overloaded) |
| Erase | Erases data (Overloaded) |
Flush |
Not supported |
GetHashCode |
Inherited from Object |
GetLifetimeService |
Inherited from MarshalByRefObject |
GetType |
Inherited from Object |
InitializedLifetimeService |
Inherited from MarshalByRefObject |
| IsEqual | Compares the LOB data referenced by the two OracleBlobs |
| Read | Reads a specified amount of bytes from the ODP.NET LOB Type instance and populates the buffer |
ReadByte |
Inherited from Stream |
| Search | Searches for a binary pattern in the current instance of an OracleBlob |
| Seek | Sets the position in the current LOB stream |
| SetLength | Trims or truncates the BLOB value to the specified length |
ToString |
Inherited from Object |
| Write | Writes the supplied buffer into the OracleBlob |
WriteByte |
Inherited from Stream |
Append appends the supplied data to the end of the current OracleBlob instance.
Overload List:
This instance method appends the BLOB data referenced by the provided OracleBlob object to the current OracleBlob instance.
This instance method appends data from the supplied byte array buffer to the end of the current OracleBlob instance.
This instance method appends the BLOB data referenced by the provided OracleBlob object to the current OracleBlob instance.
Declaration
// C#
public void Append(OracleBlob obj);
Parameters
obj
An object of OracleBlob.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The parameter has a different connection than the object, OracleConnection is not opened, or OracleConnection has been reopened.
Remarks
No character set conversions are made.
The provided object and the current instance must be using the same connection; that is, the same OracleConnection object.
This instance method appends data from the supplied byte array buffer to the end of the current OracleBlob instance.
Declaration
// C# public void Append(byte[] buffer, int offset, int count);
Parameters
buffer
An array of bytes.
offset
The zero-based byte offset in the buffer from which data is read.
count
The number of bytes to be appended.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class AppendSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob = new OracleBlob(con);
// Append 2 bytes {4, 5} to the OracleBlob
byte[] buffer = new byte[3] {4, 5, 6};
blob.Append(buffer, 0, 2);
byte[] appendBuffer = blob.Value;
// Prints "appendBuffer = 45"
Console.Write("appendBuffer = ");
for(int index = 0; index < appendBuffer.Length; index++)
{
Console.Write(appendBuffer[index]);
}
Console.WriteLine();
blob.Close();
blob.Dispose();
con.Close();
con.Dispose();
}
}
This instance method opens the BLOB.
Declaration
// C# public void BeginChunkWrite();
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
Remarks
BeginChunkWrite does not need to be called before manipulating the BLOB data. This is provided for performance reasons.
After this method is called, write operations do not cause the domain or function-based index on the column to be updated. Index updates occur only once after EndChunkWrite is called.
This instance method creates a copy of an OracleBlob object.
Declaration
// C# public object Clone();
Return Value
An OracleBlob object.
Implements
ICloneable
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
Remarks
The cloned object has the same property values as that of the object being cloned.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class CloneSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob1 = new OracleBlob(con);
// Prints "blob1.Position = 0"
Console.WriteLine("blob1.Position = " + blob1.Position);
// Set the Position before calling Clone()
blob1.Position = 1;
// Clone the OracleBlob
OracleBlob blob2 = (OracleBlob)blob1.Clone();
// Prints "blob2.Position = 1"
Console.WriteLine("blob2.Position = " + blob2.Position);
blob1.Close();
blob1.Dispose();
blob2.Close();
blob2.Dispose();
con.Close();
con.Dispose();
}
}
Overrides Stream
This instance method closes the current stream and releases any resources associated with it.
Declaration
// C# public override void Close();
This instance method compares data referenced by the current instance and that of the supplied object.
Declaration
// C# public int Compare(Int64 src_offset, OracleBlob obj, Int64 dst_offset, Int64 amount);
Parameters
src_offset
The comparison starting point (in bytes) for the current instance.
obj
The provided OracleBlob object.
dst_offset
The comparison starting point (in bytes) for the provided OracleBlob.
amount
The number of bytes to compare.
Return Value
Returns a value that is:
Less than zero: if the data referenced by the current instance is less than that of the supplied instance
Zero: if both objects reference the same data
Greater than zero: if the data referenced by the current instance is greater than that of the supplied instance
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The parameter has a different connection than the object, OracleConnection is not opened, or OracleConnection has been reopened.
ArgumentOutOfRangeException - The src_offset, the dst_offset, or the amount parameter is less than 0.
Remarks
The provided object and the current instance must be using the same connection, that is, the same OracleConnection object.
CopyTo copies data from the current instance to the provided OracleBlob object.
Overload List:
This instance method copies data from the current instance to the provided OracleBlob object.
This instance method copies data from the current OracleBlob instance to the provided OracleBlob object with the specified destination offset.
CopyTo(Int64, OracleBlob, Int64, Int64)
This instance method copies data from the current OracleBlob instance to the provided OracleBlob object with the specified source offset, destination offset, and character amounts.
This instance method copies data from the current instance to the provided OracleBlob object.
Declaration
// C#
public Int64 CopyTo(OracleBlob obj);
Parameters
obj
The OracleBlob object to which the data is copied.
Return Value
The return value is the amount copied.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - This exception is thrown if any of the following conditions exist:
The OracleConnection is not open or has been closed during the lifetime of the object.
The LOB object parameter has a different connection than the object.
Remarks
The provided object and the current instance must be using the same connection; that is, the same OracleConnection object.
This instance method copies data from the current OracleBlob instance to the provided OracleBlob object with the specified destination offset.
Declaration
// C# public Int64 CopyTo(OracleBlob obj, Int64 dst_offset);
Parameters
obj
The OracleBlob object to which the data is copied.
dst_offset
The offset (in bytes) at which the OracleBlob object is copied.
Return Value
The return value is the amount copied.
Exceptions
ObjectDisposedException - The object is already disposed.
ArgumentOutOfRangeException - The dst_offset is less than 0.
InvalidOperationException - This exception is thrown if any of the following conditions exist:
The OracleConnection is not open or has been closed during the lifetime of the object.
The LOB object parameter has a different connection than the object.
Remarks
If the dst_offset is beyond the end of the OracleBlob data, spaces are written into the OracleBlob until the dst_offset is met.
The offsets are 0-based. No character conversion is performed by this operation.
The provided object and the current instance must be using the same connection; that is, the same OracleConnection object.
This instance method copies data from the current OracleBlob instance to the provided OracleBlob object with the specified source offset, destination offset, and character amounts.
Declaration
// C# public Int64 CopyTo(Int64 src_offset,OracleBlob obj,Int64 dst_offset, Int64 amount);
Parameters
src_offset
The offset (in bytes) in the current instance, from which the data is read.
obj
The OracleBlob object to which the data is copied.
dst_offset
The offset (in bytes) at which the OracleBlob object is copied.
amount
The amount of data to be copied.
Return Value
The return value is the amount copied.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The parameter has a different connection than the object, OracleConnection is not opened, or OracleConnection has been reopened.
ArgumentOutOfRangeException - The src_offset, the dst_offset, or the amount parameter is less than 0.
Remarks
If the dst_offset is beyond the end of the OracleBlob data, spaces are written into the OracleBlob until the dst_offset is met.
The offsets are 0-based. No character conversion is performed by this operation.
The provided object and the current instance must be using the same connection; that is, the same OracleConnection object.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class CopyToSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob1 = new OracleBlob(con);
OracleBlob blob2 = new OracleBlob(con);
// Write 4 bytes, starting at buffer offset 0
byte[] buffer = new byte[4] {1, 2, 3, 4};
blob1.Write(buffer, 0, 4);
// Copy 2 bytes from byte 0 of blob1 to byte 1 of blob2
blob1.CopyTo(0, blob2, 1, 2);
byte[] copyBuffer = blob2.Value;
//Prints "Value = 012"
Console.Write("Value = ");
for(int index = 0; index < copyBuffer.Length; index++)
{
Console.Write(copyBuffer[index]);
}
Console.WriteLine();
blob1.Close();
blob1.Dispose();
blob2.Close();
blob2.Dispose();
con.Close();
con.Dispose();
}
}
This instance method releases resources allocated by this object.
Declaration
// C# public void Dispose();
Implements
IDisposable
Remarks
Once Dispose() is called, the object of OracleBlob is in an uninitialized state.
Although some properties can still be accessed, their values may not be accountable. Since resources are freed, method calls may lead to exceptions. The object cannot be reused after being disposed.
This instance method closes the BLOB referenced by the current OracleBlob instance.
Declaration
// C# public void EndChunkWrite();
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
Remarks
Index updates occur immediately if there is write operation(s) deferred by the BeginChunkWrite method.
Erase erases a portion or all data.
Overload List:
This instance method erases all data.
This instance method erases a specified portion of data.
This instance method erases all data.
Declaration
// C# public Int64 Erase();
Return Value
The number of bytes erased.
Remarks
Erase() replaces all data with zero-byte fillers.
This instance method erases a specified portion of data.
Declaration
// C# public Int64 Erase(Int64 offset, Int64 amount);
Parameters
offset
The offset from which to erase.
amount
The quantity (in bytes) to erase.
Return Value
The number of bytes erased.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - The offset or amount parameter is less than 0.
Remarks
Replaces the specified amount of data with zero-byte fillers.
This instance method compares the LOB data referenced by the two OracleBlobs.
Declaration
// C#
public bool IsEqual(OracleBlob obj);
Parameters
obj
An OracleBlob object.
Return Value
If the current OracleBlob and the provided OracleBlob refer to the same LOB, returns true. Returns false otherwise.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
Remarks
Note that this method can return true even if the two OracleBlob objects return false for == or Equals() because two different OracleBlob instances can refer to the same LOB.
The provided object and the current instance must be using the same connection, that is, the same OracleConnection object.
Overrides Stream
This instance method reads a specified amount of bytes from the ODP.NET LOB instance and populates the buffer.
Declaration
// C# public override int Read(byte[ ] buffer, int offset, int count);
Parameters
buffer
The byte array buffer to be populated.
offset
The starting offset (in bytes) at which the buffer is populated.
count
The amount of bytes to read.
Return Value
The return value indicates the number of bytes read from the LOB.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - This exception is thrown if any of the following conditions exist:
The offset or the count parameter is less than 0.
The offset is greater than or equal to the buffer.Length.
The offset and the count together are greater than the buffer.Length.
Remarks
The LOB data is read starting from the position specified by the Position property.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class ReadSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob = new OracleBlob(con);
// Write 3 bytes, starting at buffer offset 1
byte[] writeBuffer = new byte[4] {1, 2, 3, 4};
blob.Write(writeBuffer, 1, 3);
// Reset the Position for Read
blob.Position = 1;
// Read 2 bytes into buffer starting at buffer offset 1
byte[] readBuffer = new byte[4];
int bytesRead = blob.Read(readBuffer, 1, 2);
// Prints "bytesRead = 2"
Console.WriteLine("bytesRead = " + bytesRead);
// Prints "readBuffer = 0340"
Console.Write("readBuffer = ");
for(int index = 0; index < readBuffer.Length; index++)
{
Console.Write(readBuffer[index]);
}
Console.WriteLine();
blob.Close();
blob.Dispose();
con.Close();
con.Dispose();
}
}
This instance method searches for a binary pattern in the current instance of an OracleBlob.
Declaration
// C# public Int64 Search(byte[] val, int64 offset, int64 nth);
Parameters
val
The binary pattern being searched for.
offset
The 0-based offset (in bytes) starting from which the OracleBlob is searched.
nth
The specific occurrence (1-based) of the match for which the absolute offset (in bytes) is returned.
Return Value
Returns the absolute offset of the start of the matched pattern (in bytes) for the nth occurrence of the match. Otherwise, 0 is returned.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - This exception is thrown if any of the following conditions exist:
The offset is less than 0.
The nth is less than or equal to 0.
The val.Length is greater than 16383.
The nth is greater than or equal to OracleBlob.MaxSize.
The offset is greater than or equal to OracleBlob.MaxSize.
Remarks
The limit of the search pattern is 16383 bytes.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class SearchSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob = new OracleBlob(con);
// Write 7 bytes, starting at buffer offset 0
byte[] buffer = new byte[7] {1, 2, 3, 4, 1, 2, 3};
blob.Write(buffer, 0, 7);
// Search for the 2nd occurrence of a byte pattern '23'
// starting at offset 1 in the OracleBlob
byte[] pattern = new byte[2] {2 ,3};
long posFound = blob.Search(pattern, 1, 2);
// Prints "posFound = 6"
Console.WriteLine("posFound = " + posFound);
blob.Close();
blob.Dispose();
con.Close();
con.Dispose();
}
}
Overrides Stream
This instance method sets the position on the current LOB stream.
Declaration
// C# public override Int64 Seek(Int64 offset, SeekOrigin origin);
Parameters
offset
A byte offset relative to origin.
origin
A value of type System.IO.SeekOrigin indicating the reference point used to obtain the new position.
Return Value
Returns Int64 for the position.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
Remarks
If offset is negative, the new position precedes the position specified by origin by the number of bytes specified by offset.
If offset is zero, the new position is the position specified by origin.
If offset is positive, the new position follows the position specified by origin by the number of bytes specified by offset.
SeekOrigin.Begin specifies the beginning of a stream.
SeekOrigin.Current specifies the current position within a stream.
SeekOrigin.End specifies the end of a stream.
Overrides Stream
This instance method trims or truncates the BLOB value to the specified length (in bytes).
Declaration
// C#
public override void SetLength(Int64 newlen);
Parameters
newlen
The desired length of the current stream in bytes.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - The newlen parameter is less than 0.
Overrides Stream
This instance method writes the supplied buffer into the OracleBlob.
Declaration
// C# public override void Write(byte[ ] buffer, int offset, int count);
Parameters
buffer
The byte array buffer that provides the data.
offset
The 0-based offset (in bytes) from which the buffer is read.
count
The amount of data (in bytes) that is to be written into the OracleBlob.
Exceptions
ObjectDisposedException - The object is already disposed.
InvalidOperationException - The OracleConnection is not open or has been closed during the lifetime of the object.
ArgumentOutOfRangeException - This exception is thrown if any of the following conditions exist:
The offset or the count is less than 0.
The offset is greater than or equal to the buffer.Length.
The offset and the count together are greater than buffer.Length.
Remarks
Destination offset in the OracleBlob can be specified by the Position property.
Example
// C#
using System;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class WriteSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
OracleBlob blob = new OracleBlob(con);
// Set the Position for the Write
blob.Position = 0;
// Begin ChunkWrite to improve performance
// Index updates occur only once after EndChunkWrite
blob.BeginChunkWrite();
// Write to the OracleBlob in 5 chunks of 2 bytes each
byte[] b = new byte[2] {1, 2};
for(int index = 0; index < 5; index++)
{
blob.Write(b, 0, b.Length);
}
blob.EndChunkWrite();
byte[] chunkBuffer = blob.Value;
// Prints "chunkBuffer = 1212121212"
Console.Write("chunkBuffer = ");
for(int index = 0; index < chunkBuffer.Length; index++)
{
Console.Write(chunkBuffer[index]);
}
Console.WriteLine();
blob.Close();
blob.Dispose();
con.Close();
con.Dispose();
}
}