Java by API/java.sql/Clob

Clob: getCharacterStream()

 
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
    Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL", "yourName", "mypwd");
    Statement stmt = conn.createStatement();
    createBlobClobTables(stmt);
    PreparedStatement pstmt = conn.prepareStatement("INSERT INTO BlobClob VALUES(40,?,?)");
    File file = new File("blob.txt");
    FileInputStream fis = new FileInputStream(file);
    pstmt.setBinaryStream(1, fis, (int) file.length());
    file = new File("clob.txt");
    fis = new FileInputStream(file);
    pstmt.setAsciiStream(2, fis, (int) file.length());
    fis.close();
    pstmt.execute();
    ResultSet rs = stmt.executeQuery("SELECT * FROM BlobClob WHERE id = 40");
    rs.next();
    java.sql.Blob blob = rs.getBlob(2);
    java.sql.Clob clob = rs.getClob(3);
    byte blobVal[] = new byte[(int) blob.length()];
    InputStream blobIs = blob.getBinaryStream();
    blobIs.read(blobVal);
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    bos.write(blobVal);
    blobIs.close();
    char clobVal[] = new char[(int) clob.length()];
    Reader r = clob.getCharacterStream();
    r.read(clobVal);
    StringWriter sw = new StringWriter();
    sw.write(clobVal);
    r.close();
    conn.close();
  }
  public static void createBlobClobTables(Statement stmt) throws Exception {
    String Sql = "CREATE TABLE BlobClob(Id NUMBER(3), b BLOB, c CLOB)";
    try {
      stmt.executeUpdate("DROP TABLE BlobClob");
    } catch (SQLException se) {
      if (se.getErrorCode() == 942)
        System.out.println("Error dropping BlobClob table:" + se.getMessage());
    }
    if (stmt.executeUpdate(Sql) == 0)
      System.out.println("BlobClob table created...");
  }
}

Clob: getSubString(long pos, int length)

 
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class Main{
  public static Connection getConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/databaseName";
    String username = "root";
    String password = "root";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static String getCLOB(int id) throws Exception {
    Connection conn = null;
    ResultSet rs = null;
    PreparedStatement pstmt = null;
    String query = "SELECT clobData FROM tableName WHERE id = ?";
    try {
      conn = getConnection();
      pstmt = conn.prepareStatement(query);
      pstmt.setInt(1, id);
      rs = pstmt.executeQuery();
      rs.next();
      Clob clob = rs.getClob(1);
      // materialize CLOB onto client
      String wholeClob = clob.getSubString(1, (int) clob.length());
      return wholeClob;
    } finally {
      rs.close();
      pstmt.close();
      conn.close();
    }
  }
  public static void main(String args[]) throws Exception {
    System.out.println(getCLOB(01));
  }
}