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postgresql.largeobject
Class LargeObjectManager  

java.lang.Object
  postgresql.largeobject.LargeObjectManager

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public class LargeObjectManager

extends java.lang.Object

This class implements the large object interface to postgresql.

It provides methods that allow client code to create, open and delete large objects from the database. When opening an object, an instance of postgresql.largeobject.LargeObject is returned, and its methods then allow access to the object.

This class can only be created by postgresql.Connection

To get access to this class, use the following segment of code:

 import postgresql.largeobject.*;

 Connection  conn;
 LargeObjectManager lobj;

 ... code that opens a connection ...

 lobj = ((postgresql.Connection)myconn).getLargeObjectAPI();
 

Normally, client code would use the getAsciiStream, getBinaryStream, or getUnicodeStream methods in ResultSet, or setAsciiStream, setBinaryStream, or setUnicodeStream methods in PreparedStatement to access Large Objects.

However, sometimes lower level access to Large Objects are required, that are not supported by the JDBC specification.

Refer to postgresql.largeobject.LargeObject on how to manipulate the contents of a Large Object.

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Field Summary
private  postgresql.fastpath.Fastpath	fp
static int	READ           This mode indicates we want to read an object
static int	READWRITE           This mode is the default.
static int	WRITE           This mode indicates we want to write to an object

 

Constructor Summary
private	LargeObjectManager()           This prevents us being created by mere mortals
	LargeObjectManager(postgresql.Connection conn)           Constructs the LargeObject API.

 

Method Summary
int	create()           This creates a large object, returning its OID.
int	create(int mode)           This creates a large object, returning its OID
void	delete(int oid)           This deletes a large object.
LargeObject	open(int oid)           This opens an existing large object, based on its OID.
LargeObject	open(int oid, int mode)           This opens an existing large object, based on its OID
void	unlink(int oid)           This deletes a large object.

 

Methods inherited from class java.lang.Object

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

 

Field Detail

fp

private postgresql.fastpath.Fastpath fp

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WRITE

public static final int WRITE

This mode indicates we want to write to an object

See Also:

Constant Field Values

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READ

public static final int READ

This mode indicates we want to read an object

See Also:

Constant Field Values

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READWRITE

public static final int READWRITE

This mode is the default. It indicates we want read and write access to a large object

See Also:

Constant Field Values

Constructor Detail

LargeObjectManager

private LargeObjectManager()

This prevents us being created by mere mortals

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LargeObjectManager

public LargeObjectManager(postgresql.Connection conn)
                   throws java.sql.SQLException

Constructs the LargeObject API.

Important Notice
This method should only be called by postgresql.Connection

There should only be one LargeObjectManager per Connection. The postgresql.Connection class keeps track of the various extension API's and it's advised you use those to gain access, and not going direct.

Method Detail

open

public LargeObject open(int oid)
                 throws java.sql.SQLException

This opens an existing large object, based on its OID. This method assumes that READ and WRITE access is required (the default).

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open

public LargeObject open(int oid,
                        int mode)
                 throws java.sql.SQLException

This opens an existing large object, based on its OID

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create

public int create()
           throws java.sql.SQLException

This creates a large object, returning its OID.

It defaults to READWRITE for the new object's attributes.

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create

public int create(int mode)
           throws java.sql.SQLException

This creates a large object, returning its OID

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delete

public void delete(int oid)
            throws java.sql.SQLException

This deletes a large object.

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unlink

public void unlink(int oid)
            throws java.sql.SQLException

This deletes a large object.

It is identical to the delete method, and is supplied as the C API uses unlink.

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