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|
/*
* This sample demonstrate basic Lob support.
*/
import java.sql.*;
import java.io.*;
import java.util.*;
// Importing the Oracle Jdbc driver package makes the code more readable
import oracle.jdbc.*;
//needed for new CLOB and BLOB classes
import oracle.sql.*;
public class LobExample
{
public static void main (String args [])
throws Exception
{
// Register the Oracle JDBC driver
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
String url = "jdbc:oracle:oci8:@";
try {
String url1 = System.getProperty("JDBC_URL");
if (url1 != null)
url = url1;
} catch (Exception e) {
// If there is any security exception, ignore it
// and use the default
}
// Connect to the database
Connection conn =
DriverManager.getConnection (url, "scott", "tiger");
// It's faster when auto commit is off
conn.setAutoCommit (false);
// Create a Statement
Statement stmt = conn.createStatement ();
try
{
stmt.execute ("drop table basic_lob_table");
}
catch (SQLException e)
{
// An exception could be raised here if the table did not exist already.
}
// Create a table containing a BLOB and a CLOB
stmt.execute ("create table basic_lob_table (x varchar2 (30), b blob, c clob)");
// Populate the table
stmt.execute ("insert into basic_lob_table values ('one', '010101010101010101010101010101', 'onetwothreefour')");
stmt.execute ("insert into basic_lob_table values ('two', '0202020202020202020202020202', 'twothreefourfivesix')");
System.out.println ("Dumping lobs");
// Select the lobs. Since the Lob contents will be modified, we need
// to lock the table rows. This can be done by doing "select ... for
// update", but we don't need to select for update here because we
// have "autocommit" turned off and the previous "create table"
// statement already have the whole table locked.
ResultSet rset = stmt.executeQuery ("select * from basic_lob_table");
while (rset.next ())
{
// Get the lobs
BLOB blob = ((OracleResultSet)rset).getBLOB (2);
CLOB clob = ((OracleResultSet)rset).getCLOB (3);
// Print the lob contents
dumpBlob (blob);
dumpClob (clob);
// Change the lob contents
fillClob (clob, 2000);
fillBlob (blob, 4000);
}
System.out.println ("Dumping lobs again");
rset = stmt.executeQuery ("select * from basic_lob_table");
while (rset.next ())
{
// Get the lobs
BLOB blob = ((OracleResultSet)rset).getBLOB (2);
CLOB clob = ((OracleResultSet)rset).getCLOB (3);
// Print the lobs contents
dumpBlob (blob);
dumpClob (clob);
}
// Close all resources
rset.close();
stmt.close();
conn.close();
}
// Utility function to dump Clob contents
static void dumpClob (CLOB clob)
throws Exception
{
// get character stream to retrieve clob data
Reader instream = clob.getCharacterStream();
// create temporary buffer for read
char[] buffer = new char[10];
// length of characters read
int length = 0;
// fetch data
while ((length = instream.read(buffer)) != -1)
{
System.out.print("Read " + length + " chars: ");
for (int i=0; i<length; i++)
System.out.print(buffer[i]);
System.out.println();
}
// Close input stream
instream.close();
}
// Utility function to dump Blob contents
static void dumpBlob (BLOB blob)
throws Exception
{
// Get binary output stream to retrieve blob data
InputStream instream = blob.getBinaryStream();
// Create temporary buffer for read
byte[] buffer = new byte[10];
// length of bytes read
int length = 0;
// Fetch data
while ((length = instream.read(buffer)) != -1)
{
System.out.print("Read " + length + " bytes: ");
for (int i=0; i<length; i++)
System.out.print(buffer[i]+" ");
System.out.println();
}
// Close input stream
instream.close();
}
// Utility function to put data in a Clob
static void fillClob (CLOB clob, long length)
throws Exception
{
Writer outstream = clob.getCharacterOutputStream();
int i = 0;
int chunk = 10;
while (i < length)
{
outstream.write(i + "hello world", 0, chunk);
i += chunk;
if (length - i < chunk)
chunk = (int) length - i;
}
outstream.close();
}
// Utility function to put data in a Blob
static void fillBlob (BLOB blob, long length)
throws Exception
{
OutputStream outstream = blob.getBinaryOutputStream();
int i = 0;
int chunk = 10;
byte [] data = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
while (i < length)
{
data [0] = (byte)i;
outstream.write(data, 0, chunk);
i += chunk;
if (length - i < chunk)
chunk = (int) length - i;
}
outstream.close();
}
} |
