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Oracle and Java Tutorial
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I’m posting this because of a question raised against this older post on how to configure the %CLASSPATH% to find the ojdbc6.jar file. This is the lab file I use in my Database 1 class to expose students to the moving parts of writing Java programs against the Oracle database. That’s why I choose to use a CLOB data type, which requires Oracle’s DBMS_LOB package and wrapping stored procedures.

If you want the same content for MySQL, here’s the link. The full program in either blog entry is available by clicking on the fold/unfold Java Source Code Program widget at the bottom of the respective posts.

This demonstrates how to create an Java infrastructure for reading and writing large text files to an Oracle database. The example provides:

  • A FileIO.jar library that lets you enter Oracle connection parameters through a JOptionPane, and a customized JFileChooser to filter and read source files from the file system.
  • A ojdbc6.jar file, which is Oracle’s library for JDBC communication with the Oracle Databases.

The steps to compiling and testing this code are qualified below:

  • Download and install the Java Software Development Kit (JSDK) for Java 6.
  • Create a C:\JavaTest folder on Windows, or a /JavaTest directory from some mount point of your choice.
  • Download and position the ojdbc6.jar and FileIO.jar files in the JavaTest directory.
  • Create a batch file to source your environment path (%PATH% on Windows and $PATH on Linux or Mac OS X) and the two Java Archive (JAR) files. A sample batch file is noted below:
  • set PATH=C:\Program Files\Java\jdk1.6.0_07\bin;%PATH%
    set CLASSPATH=C:\JavaDev\Java6\ojdbc6.jar;C:\JavaDev\Java6\FileIO.jar;.

    You can run this file by simply typing the files first name. On Linux or Mac OS X, you first need to grant it privileges with the chmod command as 755.

  • Copy the WriteReadCLOB.java code from the bottom of this posting and also put it into the JavaTest directory.
  • Compile the WriteReadCLOB.java source code with the javac utility, as shown below:
  • javac WriteReadCLOB.java

    After you compile it, you should run it as follows:

    java WriteReadCLOB
  • Before running the code, you’ll need to seed (INSERT) a row that meets the desired hard coded criteria. It requires an ITEM_TITLE value of 'The Lord of the Rings - Fellowship of the Ring' and an ITEM_SUBTITLE of 'Widescreen Edition' in the ITEM table.
  • When it runs, you’ll see the following tabbed JOptionPane.
  • You need to enter the following values before clicking the OK button:

    • Host: The hostname of your machine.
    • Port: The port that the Oracle Listener is running on (the default value is 1521).
    • Database: The Oracle TNS Alias, which is orcl for the full database sample database or xe for the Oracle Database 10g Express Edition.
    • UserID: The user (schema) name where you’ve created an ITEM table.
    • Password: The password for the user’s account.

    In the JFileChooser, select a file to upload to the database.

    You should see what you uploaded displayed in a JFrame.

    Java Source Code Program

    The drop down unfolds the WriteReadCLOB.java source code.

    The following program has dependencies on the FileIO.jar file. You need to download it and put it in your $CLASSPATH for Linux or Mac OS X or %CLASSPATH% for Windows.

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    // --------------------------------------------------------------------
    // WriteReadCLOB.java
    // by Michael McLaughlin
    //
    // This code demonstrates reading a large text file and displaying
    // the text stream in a JLabel in a JFrame.
    //
    // The UPDATE and SELECT statements have dependencies on the
    // create_store.sql script.
    // --------------------------------------------------------------------
     
    // Java Application class imports.
    import java.awt.Dimension;
    import java.awt.Font;
    import java.awt.GridLayout;
    import java.io.Reader;
    import javax.swing.JFrame;
    import javax.swing.JLabel;
    import javax.swing.JOptionPane;
    import javax.swing.JPanel;
    import javax.swing.JScrollPane;
    import javax.swing.JTextArea;
     
    // Generic JDBC imports.
    import java.sql.CallableStatement;
    import java.sql.Clob;
    import java.sql.Connection;
    import java.sql.DatabaseMetaData;
    import java.sql.ResultSet;
    import java.sql.ResultSetMetaData;
    import java.sql.SQLException;
    import java.sql.Statement;
     
    // Oracle JDBC import.
    import oracle.jdbc.driver.OracleDriver;
    import oracle.jdbc.pool.OracleDataSource;
     
    // Include book libraries (available at publisher website).
    import plsql.jdbc.DataConnectionPane;
    import plsql.fileio.FileIO;
    // -------------------------------------------------------------------/
    public class WriteReadCLOB extends JFrame {
      // Define database connections.
      private String host;
      private String port;
      private String dbname;
      private String userid;
      private String passwd;
     
      // Define data connection pane.
      private DataConnectionPane message = new DataConnectionPane();
     
      // Construct the class.
      public WriteReadCLOB (String s) {
        super(s);
     
        // Get database connection values or exit.
        if (JOptionPane.showConfirmDialog(this,message
              ,"Set Oracle Connection String Values"
              ,JOptionPane.OK_CANCEL_OPTION) == 0) {
     
          // Set class connection variables.
          host = message.getHost();
          port = message.getPort();
          dbname = message.getDatabase();
          userid = message.getUserID();
          passwd = message.getPassword();
     
          // Print connection to console (debugging tool).
          message.getConnection();
     
          // Create a JPanel for data display.
          ManageCLOB panel = new ManageCLOB();
     
          // Configure the JPanel.
          panel.setOpaque(true);
          setContentPane(panel);
     
          // Configure the JFrame.
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setLocation(100,100);
          pack();
          setVisible(true); }
        else
          System.exit(1); }
      // -------------------------------------------------------------------/
      private class ManageCLOB extends JPanel {
     
        // Define display variables.
        private String clobText;
        private JScrollPane scrollPane;
        private JTextArea textArea;
        // -----------------------------------------------------------------/
        public ManageCLOB () {
          // Set layout manager.
          super(new GridLayout(1,0));
     
          // Assign file read to String.
          clobText = FileIO.openFile(FileIO.findFile(this));
     
          // Insert record before querying it.
          if (clobText.length() > 0) {
            if (insertClob(host,port,dbname,userid,passwd,clobText))
              clobText = getQuery(host,port,dbname,userid,passwd);
            else
              clobText = null; }
          else
            System.exit(2);
     
          // Construct text area and format it.
          textArea = new JTextArea(clobText);
          textArea.setEditable(false);
          textArea.setFont(new Font(Font.SANS_SERIF,Font.PLAIN,14));
          textArea.setLineWrap(true);
          textArea.setRows(10);
          textArea.setSize(400,100);
          textArea.setWrapStyleWord(true);
     
          // Put the image in container, and add label to panel.
          scrollPane = new JScrollPane(textArea);
          add(scrollPane); }
        // ---------------------------------------------------------------/
        private Boolean insertClob(String host,String port,String dbname
                                  ,String user,String pswd,String fileString) {
     
          try
          {
            // Set the Pooled Connection Source
            OracleDataSource ods = new OracleDataSource();
            String url = "jdbc:oracle:thin:@//"+host+":"+port+"/"+dbname;
            ods.setURL(url);
            ods.setUser(userid);
            ods.setPassword(passwd);
     
            // Define connection.
            Connection conn = ods.getConnection();
     
            // Create statement.
            CallableStatement stmt =
              conn.prepareCall("UPDATE item "+
                               "SET    item_desc = ? "+
                               "WHERE  item_title = "+
                               "'The Lord of the Rings - Fellowship of the Ring'"+
                               "AND    item_subtitle = 'Widescreen Edition'");
     
            // Set string into statement.
            stmt.setString(1,fileString);
     
            // Execute query.
            if (stmt.execute())
              conn.commit();
     
            // Close resources.
            stmt.close();
            conn.close();
     
            // Return CLOB as a String data type.
            return true; } // End of connection try-block.
     
          catch (SQLException e) {
            if (e.getSQLState() == null) {
              System.out.println(
                new SQLException("Oracle Thin Client Net8 Connection Error.",
                                 "ORA-" + e.getErrorCode() +
                                 ": Incorrect Net8 thin client arguments:\n\n" +
                                 "  host name     [" + host + "]\n" +
                                 "  port number   [" + port + "]\n" +
                                 "  database name [" + dbname + "]\n"
                                 , e.getErrorCode()).getSQLState());
     
              // Return an empty String on error.
              return false; }
            else {
              System.out.println(e.getMessage());
     
              // Return an empty String on error.
              return false; }}}
        // -----------------------------------------------------------------/
        private String getQuery(String host,String port,String dbname
                               ,String user,String pswd) {
     
          // Define method variables.
          char[] buffer;
          int count = 0;
          int length = 0;
          String data = null;
          String[] type;
          StringBuffer sb;
     
          try {
            // Set the Pooled Connection Source
            OracleDataSource ods = new OracleDataSource();
            String url = "jdbc:oracle:thin:@//"+host+":"+port+"/"+dbname;
            ods.setURL(url);
            ods.setUser(userid);
            ods.setPassword(passwd);
     
            // Define connection.
            Connection conn = ods.getConnection();
     
            // Define metadata object.
            DatabaseMetaData dmd = conn.getMetaData();
     
            // Create statement.
            Statement stmt = conn.createStatement();
     
            // Execute query.
            ResultSet rset =
              stmt.executeQuery(
                "SELECT item_desc " +
                "FROM   item " +
                "WHERE  item_title = " +
                "'The Lord of the Rings - Fellowship of the Ring'"+
                "AND    item_subtitle = 'Widescreen Edition'");
     
            // Get the query metadata, size array and assign column values.
            ResultSetMetaData rsmd = rset.getMetaData();
            type = new String[rsmd.getColumnCount()];
            for (int col = 0;col < rsmd.getColumnCount();col++)
              type[col] = rsmd.getColumnTypeName(col + 1);
     
            // Read rows and only CLOB data type columns.
            while (rset.next()) {
              for (int col = 0;col < rsmd.getColumnCount();col++) {
                if (type[col] == "CLOB") {
                  // Assign result set to CLOB variable.
                  Clob clob = rset.getClob(col + 1);
     
                  // Check that it is not null and read the character stream.
                  if (clob != null) {
                    Reader is = clob.getCharacterStream();
     
                    // Initialize local variables.
                    sb = new StringBuffer();
                    length = (int) clob.length();
     
                    // Check CLOB is not empty.
                    if (length > 0) {
     
                      // Initialize control structures to read stream.
                      buffer = new char[length];
                      count = 0;
     
                      // Read stream and append to StringBuffer.
                      try {
                        while ((count = is.read(buffer)) != -1)
                          sb.append(buffer);
     
                        // Assign StringBuffer to String.
                        data = new String(sb); }
                      catch (Exception e) {} }
                    else
                      data = (String) null; }
                  else
                    data = (String) null; }
                else {
                  data = (String) rset.getObject(col + 1); }}}
     
            // Close resources.
            rset.close();
            stmt.close();
            conn.close();
     
            // Return CLOB as a String data type.
            return data; }
          catch (SQLException e) {
            if (e.getSQLState() == null) {
              System.out.println(
                new SQLException("Oracle Thin Client Net8 Connection Error.",
                                 "ORA-" + e.getErrorCode() +
                                 ": Incorrect Net8 thin client arguments:\n\n" +
                                 "  host name     [" + host + "]\n" +
                                 "  port number   [" + port + "]\n" +
                                 "  database name [" + dbname + "]\n"
                                 , e.getErrorCode()).getSQLState());
     
              // Return an empty String on error.
              return data; }
            else {
              System.out.println(e.getMessage());
              return data; }}
            finally {
              if (data == null) System.exit(1); }}}
      // -----------------------------------------------------------------/
      public static void main(String[] args) {
        // Define window.
        WriteReadCLOB frame = new WriteReadCLOB("Write & Read CLOB Text"); }}

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