/*
 * This program operates on the table Cars(name,image)
 * where name is a string and image is a blob.
 *
 * usage: java ReadBlob car-name image-file-name
 *
 * The image field for the given car is read from
 * the database and written to the image file
 *
 */

// You need to import the java.sql package to use JDBC
import oracle.sql.*;
import oracle.jdbc.driver.*;
import java.sql.*;
import java.io.*;

class ReadBlob {

    public static void main(String[] args) throws SQLException {

	if(args.length<2){
	    System.out.println("usage:  java ReadBlob name filename");
	    System.exit(1);
	}
	
        String stname = args[0];
        String fname = args[1];

	// Load the Oracle JDBC driver
	DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

	// Connect to the database
	// You can put a database name after the @ sign in the connection URL.
	Connection conn =
	    DriverManager.getConnection ("jdbc:oracle:thin:@occs.cs.oberlin.edu:1521:occs", "alice", "tiger");
	conn.setAutoCommit(false);

	PreparedStatement stmt = conn.prepareStatement("select * "+
						       "from cars "+
						       "where name = ? "+
						       "for update");
	stmt.setString(1,stname);
	ResultSet rset = stmt.executeQuery();
	BLOB blob = null;
	if(rset.next()){
	    blob = ((OracleResultSet)rset).getBLOB(2);
	}
	else {
	    System.out.println("Student "+stname+" not found");
	    System.exit(1);
	}

	File imageFile = new File(fname);
	InputStream instream = null;
	FileOutputStream outstream = null;
	try {
	    outstream = new FileOutputStream(imageFile);
	    instream = blob.getBinaryStream();
	    int size = blob.getBufferSize();
	    byte[] buffer = new byte[size];
	    int length;
	    while((length = instream.read(buffer))!=-1)
		outstream.write(buffer,0,length);
	    instream.close();
	    outstream.close();
	}
	catch (IOException ie){
	    System.out.println(ie);
	    System.exit(1);
	}
	conn.commit();

	// Close the Statement
	stmt.close();
	
	// Close the connection
	conn.close();   
    }
}