tracksample.java

此程序都是企业级 的数据库开发程序 全面揭示了JAVA对数据库的操作

package sql99;

import javax.swing.*;
import java.io.*;
import java.sql.*;
import connections.*;

public class TrackSample {
  private int recordingid;
  private int tracknumber;
  private File sampleFile;

  Connection connection;
  Statement statement;
  ResultSet resultset;

  public TrackSample(int id, int number, File file) {
    recordingid = id;
    tracknumber = number;
    sampleFile = file;
  }

  void getConnection(boolean autocommit) throws SQLException {
    connection = ConnectionFactory.getConnection();
    connection.setAutoCommit(autocommit);
  } 

  Statement getStatement(boolean autocommit) throws SQLException {
    getConnection(autocommit);
    return connection.createStatement();
  } 

  PreparedStatement getPreparedStatement(String sql, boolean autocommit) 
                                         throws SQLException {
    getConnection(autocommit);
    return connection.prepareStatement(sql);
  } 

  public void create() {
    BufferedInputStream in = null;
    OutputStream out = null;

    try {

      // insert a row into the BLOB table, use the empty_blob()
      // construct for the BLOB field. empty_blob() creates the
      // BLOB locator for Oracle
      statement = getStatement(false);
      statement.executeUpdate("insert into tracksamples " +
                              "(recordingid, tracknumber, sample) " +
                              "values (1, 1, empty_blob())");

      // Retrieve the row that was just inserted
      resultset = 
        statement.executeQuery("select sample from tracksamples " +
                               "where recordingid=1 and tracknumber=1 " +
                               "for update");

      if (resultset.next()) {

        // Get the BLOB locator
        Blob blob = resultset.getBlob(1);

        // Get the output stream which will be used to send
        // data to the table. Use Oracle extension because
        // JDBC 2.0 does not support writing data to BLOB
        out = ((oracle.sql.BLOB) blob).getBinaryOutputStream();

        // Let driver compute buffer size for writing to BLOB
        int bufferSize = (int) ((oracle.sql.BLOB) blob).getBufferSize();

        // Create a buffered stream to read from the file
        in = new BufferedInputStream(new FileInputStream(sampleFile), 
                                     bufferSize);

        // Create a byte buffer and start reading from the file
        byte[] b = new byte[bufferSize];
        int count = in.read(b, 0, bufferSize);

        // write the bytes using the OutputStream
        // loop until all bytes are written to the table
        System.out.print("Storing data in database.");
        while (count != -1) {
          out.write(b, 0, count);
          System.out.print(".");
          count = in.read(b, 0, bufferSize);
        } 

        System.out.println("Complete");

        // Close the Input and Output Streams
        // The Output stream MUST be closed before the commit
        out.close();
        out = null;
        in.close();
        in = null;

        // And finally, commit the changes
        connection.commit();
      } 
    } catch (Exception e) {
      e.printStackTrace();
      try {
        connection.rollback();
      } catch (Exception ignored) {}
    } finally {

      // if an exception occurred, the streams may not have been closed
      // so close them here if needed
      if (out != null) {
        try {
          out.close();
        } catch (Exception ignored) {}
      } 
      if (in != null) {
        try {
          in.close();
        } catch (Exception ignored) {}

      } 
      close();
    } 
    return;
  } 

  public void retrieve() {
    int bufferSize;
    BufferedOutputStream out = null;
    InputStream in = null;

    try {
      statement = getStatement(false);

      // Retrieve the row that has the selected name
      resultset = 
        statement.executeQuery("select sample from tracksamples " +
                               "where tracknumber= " + tracknumber + 
                               "and recordingid=" + recordingid);

      if (resultset.next()) {

        // Get the BLOB locator
        Blob blob = resultset.getBlob(1);

        // Get the input stream which will be used to read
        // data from the table.
        in = blob.getBinaryStream();

        bufferSize = (int) ((oracle.sql.BLOB) blob).getBufferSize();

        // Create a buffered stream to write to the file
        out = new BufferedOutputStream(new FileOutputStream(sampleFile), 
                                       bufferSize);

        // Create a byte buffer and start reading from the file
        byte[] b = new byte[bufferSize];
        int count = in.read(b, 0, bufferSize);

        // write the bytes using the OutputStream
        // loop until all bytes are written to the table
        System.out.print("Writing file.");
        while (count != -1) {
          System.out.print(".");
          out.write(b, 0, count);
          count = in.read(b, 0, (int) bufferSize);
        } 
        System.out.println("Complete");
      } 

      // Close the Input and Output Streams
      out.flush();
      out.close();
      out = null;
      in.close();
      in = null;

    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (out != null) {
        try {
          out.close();
        } catch (Exception ignored) {}
      } 
      if (in != null) {
        try {
          in.close();
        } catch (Exception ignored) {}

      } 
      close();
    } 
    return;
  } 

  void close() {
    ConnectionFactory.close(resultset);
    ConnectionFactory.close(statement);
    ConnectionFactory.close(connection);
  } 
}