org.postgresql.largeobject.LargeObjectManager Maven / Gradle / Ivy
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/*-------------------------------------------------------------------------
*
* Copyright (c) 2003-2011, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgjdbc/org/postgresql/largeobject/LargeObjectManager.java,v 1.25 2011/08/02 13:50:28 davecramer Exp $
*
*-------------------------------------------------------------------------
*/
package org.postgresql.largeobject;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.postgresql.core.BaseConnection;
import org.postgresql.fastpath.Fastpath;
import org.postgresql.fastpath.FastpathArg;
import org.postgresql.util.PSQLException;
import org.postgresql.util.GT;
import org.postgresql.util.PSQLState;
/**
* This class implements the large object interface to org.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
* org.postgresql.largeobject.LargeObject is returned, and its methods then allow
* access to the object.
*
*
This class can only be created by org.postgresql.Connection
*
*
To get access to this class, use the following segment of code:
*
* import org.postgresql.largeobject.*;
*
* Connection conn;
* LargeObjectManager lobj;
*
* ... code that opens a connection ...
*
* lobj = ((org.postgresql.PGConnection)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 org.postgresql.largeobject.LargeObject on how to manipulate the
* contents of a Large Object.
*
* @see java.sql.ResultSet#getAsciiStream
* @see java.sql.ResultSet#getBinaryStream
* @see java.sql.ResultSet#getUnicodeStream
* @see java.sql.PreparedStatement#setAsciiStream
* @see java.sql.PreparedStatement#setBinaryStream
* @see java.sql.PreparedStatement#setUnicodeStream
*/
public class LargeObjectManager
{
// the fastpath api for this connection
private Fastpath fp;
private BaseConnection conn;
/**
* This mode indicates we want to write to an object
*/
public static final int WRITE = 0x00020000;
/**
* This mode indicates we want to read an object
*/
public static final int READ = 0x00040000;
/**
* This mode is the default. It indicates we want read and write access to
* a large object
*/
public static final int READWRITE = READ | WRITE;
/**
* This prevents us being created by mere mortals
*/
private LargeObjectManager()
{
}
/**
* Constructs the LargeObject API.
*
*
Important Notice
*
This method should only be called by org.postgresql.Connection
*
*
There should only be one LargeObjectManager per Connection. The
* org.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.
*/
public LargeObjectManager(BaseConnection conn) throws SQLException
{
this.conn = conn;
// We need Fastpath to do anything
this.fp = conn.getFastpathAPI();
// Now get the function oid's for the api
//
// This is an example of Fastpath.addFunctions();
//
String sql;
if (conn.getMetaData().supportsSchemasInTableDefinitions())
{
sql = "SELECT p.proname,p.oid " +
" FROM pg_catalog.pg_proc p, pg_catalog.pg_namespace n " +
" WHERE p.pronamespace=n.oid AND n.nspname='pg_catalog' AND (";
}
else
{
sql = "SELECT proname,oid FROM pg_proc WHERE ";
}
sql += " proname = 'lo_open'" +
" or proname = 'lo_close'" +
" or proname = 'lo_creat'" +
" or proname = 'lo_unlink'" +
" or proname = 'lo_lseek'" +
" or proname = 'lo_tell'" +
" or proname = 'loread'" +
" or proname = 'lowrite'" +
" or proname = 'lo_truncate'";
if (conn.getMetaData().supportsSchemasInTableDefinitions())
{
sql += ")";
}
ResultSet res = conn.createStatement().executeQuery(sql);
if (res == null)
throw new PSQLException(GT.tr("Failed to initialize LargeObject API"), PSQLState.SYSTEM_ERROR);
fp.addFunctions(res);
res.close();
conn.getLogger().debug("Large Object initialised");
}
/**
* This opens an existing large object, based on its OID. This method
* assumes that READ and WRITE access is required (the default).
*
* @param oid of large object
* @return LargeObject instance providing access to the object
* @exception SQLException on error
* @deprecated As of 8.3, replaced by {@link #open(long)}
*/
public LargeObject open(int oid) throws SQLException
{
return open((long)oid);
}
/**
* This opens an existing large object, based on its OID. This method
* assumes that READ and WRITE access is required (the default).
*
* @param oid of large object
* @return LargeObject instance providing access to the object
* @exception SQLException on error
*/
public LargeObject open(long oid) throws SQLException
{
return open(oid, READWRITE);
}
/**
* This opens an existing large object, based on its OID
*
* @param oid of large object
* @param mode mode of open
* @return LargeObject instance providing access to the object
* @exception SQLException on error
* @deprecated As of 8.3, replaced by {@link #open(long, int)}
*/
public LargeObject open(int oid, int mode) throws SQLException
{
return open((long)oid, mode);
}
/**
* This opens an existing large object, based on its OID
*
* @param oid of large object
* @param mode mode of open
* @return LargeObject instance providing access to the object
* @exception SQLException on error
*/
public LargeObject open(long oid, int mode) throws SQLException
{
if (conn.getAutoCommit())
throw new PSQLException(GT.tr("Large Objects may not be used in auto-commit mode."),
PSQLState.NO_ACTIVE_SQL_TRANSACTION);
return new LargeObject(fp, oid, mode);
}
/**
* This creates a large object, returning its OID.
*
*
It defaults to READWRITE for the new object's attributes.
*
* @return oid of new object
* @exception SQLException on error
* @deprecated As of 8.3, replaced by {@link #createLO()}
*/
public int create() throws SQLException
{
return create(READWRITE);
}
/**
* This creates a large object, returning its OID.
*
*
It defaults to READWRITE for the new object's attributes.
*
* @return oid of new object
*/
public long createLO() throws SQLException
{
return createLO(READWRITE);
}
/**
* This creates a large object, returning its OID
*
* @param mode a bitmask describing different attributes of the new object
* @return oid of new object
* @exception SQLException on error
*/
public long createLO(int mode) throws SQLException
{
if (conn.getAutoCommit())
throw new PSQLException(GT.tr("Large Objects may not be used in auto-commit mode."),
PSQLState.NO_ACTIVE_SQL_TRANSACTION);
FastpathArg args[] = new FastpathArg[1];
args[0] = new FastpathArg(mode);
return fp.getOID("lo_creat", args);
}
/**
* This creates a large object, returning its OID
*
* @param mode a bitmask describing different attributes of the new object
* @return oid of new object
* @exception SQLException on error
* @deprecated As of 8.3, replaced by {@link #createLO(int)}
*/
public int create(int mode) throws SQLException
{
long oid = createLO(mode);
return (int)oid;
}
/**
* This deletes a large object.
*
* @param oid describing object to delete
* @exception SQLException on error
*/
public void delete(long oid) throws SQLException
{
FastpathArg args[] = new FastpathArg[1];
args[0] = Fastpath.createOIDArg(oid);
fp.fastpath("lo_unlink", false, args);
}
/**
* This deletes a large object.
*
*
It is identical to the delete method, and is supplied as the C API uses
* unlink.
*
* @param oid describing object to delete
* @exception SQLException on error
* @deprecated As of 8.3, replaced by {@link #unlink(long)}
*/
public void unlink(int oid) throws SQLException
{
delete((long)oid);
}
/**
* This deletes a large object.
*
*
It is identical to the delete method, and is supplied as the C API uses
* unlink.
*
* @param oid describing object to delete
* @exception SQLException on error
*/
public void unlink(long oid) throws SQLException
{
delete(oid);
}
/**
* This deletes a large object.
*
* @param oid describing object to delete
* @exception SQLException on error
* @deprecated As of 8.3, replaced by {@link #delete(long)}
*/
public void delete(int oid) throws SQLException
{
delete((long)oid);
}
}