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/*
* @author Savitha
* @version 1.0
*
* Development Environment : Oracle JDeveloper 10g
* Name of the Application : ClobManipulationIn10g.java
* Creation/Modification History :
*
* Savitha 17-Mar-2004 Created.
*/
// Java SQL classes
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
// Oracle JDBC driver class
import oracle.jdbc.OracleDriver;
// Java IO classes
import java.io.IOException;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
//Java Util classes
import java.util.Properties;
/**
* This class demonstrates the Oracle JDBC 10g enhanced features for inserting
* and retrieving CLOB data from the database. Using the new features, large
* data of more than 32765 bytes can be inserted into the database using the
* existing PreparedStatement.setString() and PreparedStatement.getString()
* methods.
*/
public class ClobManipulationIn10g {
/* Database Connection object */
private Connection conn = null;
/* Variables to hold database details */
private String url = null;
private String user = null;
private String password = null;
// Create a property object to hold the username, password and
// the new property SetBigStringTryClob.
private Properties props = new Properties();
/* String to hold file name */
private String fileName = null;
/**
* Default Constructor to instantiate and get a handle to class methods
* and variables.
*/
public ClobManipulationIn10g(String fileName) {
this.fileName = fileName;
}
/**
* Main runnable class.
*/
public static void main(String[] args) throws SQLException {
// Instantiate the main class.
ClobManipulationIn10g clobManipulationIn10g =
new ClobManipulationIn10g("test.xml");
// Load the Oracle JDBC driver class.
DriverManager.registerDriver(new OracleDriver());
// Load the database details into the variables.
String dbUrl = "jdbc:oracle:thin:@127.0.0.1:1521:xe";
clobManipulationIn10g.url = dbUrl;
// Replace the username where the table 'clob_tab' was created.
clobManipulationIn10g.user = "user";
// Replace the password of the username.
clobManipulationIn10g.password = "pwd";
// Populate the property object to hold the username, password and
// the new property 'SetBigStringTryClob' which is set to true. Setting
// this property allows inserting of large data using the existing
// setString() method, to a CLOB column in the database.
clobManipulationIn10g.props.put("user", clobManipulationIn10g.user );
clobManipulationIn10g.props.put("password", clobManipulationIn10g.password);
clobManipulationIn10g.props.put("SetBigStringTryClob", "true");
// Check if the table 'CLOB_TAB' is present in the database.
clobManipulationIn10g.checkTables();
// Call the methods to insert and select CLOB from the database.
clobManipulationIn10g.insertClob();
// clobManipulationIn10g.selectClob();
System.out.println("END...");
}
/*
* This method will insert the data into a CLOB column in the database.
* Oracle JDBC 10g has enhanced the existing PreparedStatement.setString()
* method for setting the data more than 32765 bytes. So, using setString(),
* it is now easy to insert CLOB data into the database directly.
*/
private void insertClob() throws SQLException {
// Create a PreparedStatement object.
PreparedStatement pstmt = null;
try {
// Create the database connection, if it is closed.
if ((conn==null)||conn.isClosed()){
// Connect to the database.
conn = DriverManager.getConnection( this.url, this.props );
}
// Create SQL query to insert data into the CLOB column in the database.
String sql ="INSERT INTO RECEPTION_TMP (NUM_ENR,DAT_REC,CONTENU) VALUES (?,?,?)";
// Read a big file(larger than 32765 bytes)
String str = this.readFile();
// Create the OraclePreparedStatement object
pstmt = conn.prepareStatement(sql);
// Use the same setString() method which is enhanced to insert
// the CLOB data. The string data is automatically transformed into a
// clob and inserted into the database column. Make sure that the
// Connection property - 'SetBigStringTryClob' is set to true for
// the insert to happen.
pstmt.setString(1,"str");
pstmt.setDate(2,null);
pstmt.setString(3,str);
// Execute the PreparedStatement
pstmt.executeUpdate();
} catch (SQLException sqlex) {
sqlex.printStackTrace();
// Catch Exceptions and display messages accordingly.
System.out.println("SQLException while connecting and inserting into " +
"the database table: " + sqlex.toString());
} catch (Exception ex) {
System.out.println("Exception while connecting and inserting into the" +
" database table: " + ex.toString());
} finally {
// Close the Statement and the connection objects.
if (pstmt!=null) pstmt.close();
if (conn!=null) conn.close();
}
}
/*
* This method reads the CLOB data from the database by using getString()
* method.
*/
private void selectClob() throws SQLException {
// Create a PreparedStatement object
PreparedStatement pstmt = null;
// Create a ResultSet to hold the records retrieved.
ResultSet rset = null;
try {
// Create the database connection, if it is closed.
if ((conn==null)||conn.isClosed()){
// Connect to the database.
conn = DriverManager.getConnection( this.url, this.props );
}
// Create SQL query statement to retrieve records having CLOB data from
// the database.
String sqlCall = "SELECT clob_col FROM clob_tab";
pstmt= conn.prepareStatement(sqlCall);
// Execute the PrepareStatement
rset = pstmt.executeQuery();
String clobVal = null;
// Get the CLOB value from the resultset
while (rset.next()) {
clobVal = rset.getString(1);
System.out.println("CLOB length: "+clobVal.length());
}
} catch (SQLException sqlex) {
// Catch Exceptions and display messages accordingly.
System.out.println("SQLException while connecting and querying the " +
"database table: " + sqlex.toString());
} catch (Exception ex) {
System.out.println("Exception while connecting and querying the " +
"database table: " + ex.toString());
} finally {
// Close the resultset, statement and the connection objects.
if (rset !=null) rset.close();
if (pstmt!=null) pstmt.close();
if (conn!=null) conn.close();
}
}
/**
* Method to check if the table ('CLOB_TAB') exists in the database; if not
* then it is created.
*
* Table Name: CLOB_TAB
* Column Name Type
* -----------------------------------
* col_col CLOB
*/
private void checkTables() {
Statement stmt = null;
ResultSet rset = null;
try {
// Create the database connection, if it is closed.
if ((conn==null)||conn.isClosed()){
// Connect to the database.
conn = DriverManager.getConnection( this.url, this.props );
}
// Create Statement object
stmt = conn.createStatement();
// Check if the table is present
rset = stmt.executeQuery(" SELECT table_name FROM user_tables "+
" WHERE table_name = 'CLOB_TAB' ");
// If the table is not present, then create the table.
if (!rset.next()) {
// Table does not exist, create it
stmt.executeUpdate(" CREATE TABLE clob_tab(clob_col CLOB)");
}
} catch (SQLException sqlEx) {
System.out.println("Could not create table clob_tab : "
+sqlEx.toString());
} finally {
try {
if( rset != null ) rset.close();
if( stmt != null ) stmt.close();
if (conn!=null) conn.close();
} catch(SQLException ex) {
System.out.println("Could not close objects in checkTables method : "
+ex.toString());
}
}
}
/*
* This method reads the specified text file and, returns the content
* as a string.
*/
private String readFile()
throws FileNotFoundException, IOException{
// Read the file whose content has to be passed as String
BufferedReader br = new BufferedReader(new FileReader(fileName));
String nextLine = "";
StringBuffer sb = new StringBuffer();
while ((nextLine = br.readLine()) != null) {
sb.append(nextLine);
}
// Convert the content into to a string
String clobData = sb.toString();
// Return the data.
return clobData;
}
} |
