JavaでCLOB型を文字列に変換するにはどうすればよいですか?

Reader r = clob.getCharacterStream();

int j = 0;
StringBuffer buffer = new StringBuffer();
int ch;
while ((ch = r.read())!=-1) {
   buffer.append(""+(char)ch);
}
System.out.println(buffer.toString());
j++;

System.out.println(buffer.toString());

CREATE TABLE Technologies (Name VARCHAR(255), Type VARCHAR(255), Article LONGTEXT);

import java.io.FileReader;
import java.io.Reader;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
public class ClobToString {
   public static void main(String args[]) throws Exception {
      //Registering the Driver
      DriverManager.registerDriver(new com.mysql.jdbc.Driver());
      //Getting the connection
      String mysqlUrl = "jdbc:mysql://localhost/sampledatabase";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating a Statement object
      Statement stmt = con.createStatement();
      //Inserting values
      String query = "INSERT INTO Technologies_data VALUES (?, ?, ?)";
      PreparedStatement pstmt = con.prepareStatement(query);
      pstmt.setString(1, "JavaFX");
      pstmt.setString(2, "Java Library");
      FileReader reader = new FileReader("E:\images\javafx_contents.txt");
      pstmt.setClob(3, reader);
      pstmt.execute();
      pstmt.setString(1, "CoffeeScript");
      pstmt.setString(2, "Scripting Language");
      reader = new FileReader("E:\images\coffeescript_contents.txt");
      pstmt.setClob(3, reader);
      pstmt.execute();
      pstmt.setString(1, "Cassandra");
      pstmt.setString(2, "NoSQL Database");
      reader = new FileReader("E:\images\cassandra_contents.txt");
      pstmt.setClob(3, reader);
      pstmt.execute();
      //Retrieving the data
      ResultSet rs = stmt.executeQuery("select * from Technologies_data");
      System.out.println("Contents of the table are: ");
      while(rs.next()) {
         System.out.println("Article: "+rs.getString("Name"));
         Clob clob = rs.getClob("Article");
         Reader r = clob.getCharacterStream();
         StringBuffer buffer = new StringBuffer();
         int ch;
         while ((ch = r.read())!=-1) {
            buffer.append(""+(char)ch);
         }
         System.out.println("Contents: "+buffer.toString());
         System.out.println(" ");
      }
   }
}

Connection established......
Contents of the table are:
Article: JavaFX
Contents: JavaFX is a Java library using which you can develop Rich Internet Applications. By using Java technology, these applications have a browser penetration rate of 76%.
Article: CoffeeScript
Contents: CoffeeScript is a lightweight language based on Ruby and Python which transcompiles (compiles from one source language to another) into JavaScript. It provides better syntax avoiding the quirky parts of JavaScript, still retaining the flexibility and beauty of the language.
Article: Cassandra
Contents: Apache Cassandra is a highly scalable, high-performance distributed database designed to handle large amounts of data across many commodity servers,
providing high availability with no single point of failure. It is a type of NoSQL database. Let us first understand what a NoSQL database does.