transactionbean.java

来自「servletjsp一些应用程序」· Java 代码 · 共 85 行

package coreservlets.beans;

import java.io.*;
import java.sql.*;
import java.util.*;
import coreservlets.*;

/** Bean for performing JDBC transactions. After specifying the
 *  the connection, submit a block of SQL statements as a
 *  single transaction by calling execute. If an SQLException
 *  occurs, any prior statements are automatically rolled back.
 *  <P>
 *  Taken from Core Servlets and JavaServer Pages 2nd Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  http://www.coreservlets.com/.
 *  &copy; 2003 Marty Hall and Larry Brown.
 *  May be freely used or adapted.
 */

public class TransactionBean {
  private Connection connection;

  public void setConnection(Connection connection) {
    this.connection = connection;
  }

  public void setConnection(String driver, String url,
                            String username, String password) {
    setConnection(ConnectionInfoBean.getConnection(
                     driver, url, username, password));
  }

  public Connection getConnection() {
    return(connection);
  }

  public void execute(List list) throws SQLException {
     execute((String[])list.toArray(new String[list.size()]));
  }

  public void execute(String transaction)
      throws SQLException {
    execute(new String[] { transaction });
  }

  /** Execute a block of SQL statements as a single
   *  transaction.  If an SQLException occurs, a rollback
   *  is attempted and the exception is thrown.
   */

    public void execute(String[] transaction)
      throws SQLException {
    if (connection == null) {
      throw new SQLException("No connection available.");
    }
    boolean autoCommit = connection.getAutoCommit();
    try {
      connection.setAutoCommit(false);
      Statement statement = connection.createStatement();
      for(int i=0; i<transaction.length; i++) {
        statement.execute(transaction[i]);
      }
      statement.close();
    } catch(SQLException sqle) {
      connection.rollback();
      throw sqle;
    } finally {
      connection.commit();
      connection.setAutoCommit(autoCommit);
    }
  }

  public void close() {
    if (connection != null) {
      try {
        connection.close();
      } catch(SQLException sqle) {
        System.err.println(
          "Failed to close connection: " + sqle);
      } finally {
        connection = null;
      }
    }
  }
}