GetDBInfo.java Source code

Introduction

Here is the source code for GetDBInfo.java

Source

/*
 * Copyright (c) 2000 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 2nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book (recommended),
 * visit http://www.davidflanagan.com/javaexamples2.
 */

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

/**
 * This class uses the DatabaseMetaData class to obtain information about the
 * database, the JDBC driver, and the tables in the database, or about the
 * columns of a named table.
 */
public class GetDBInfo {
    public static void main(String[] args) {
        Connection c = null; // The JDBC connection to the database server
        try {
            // Look for the properties file DB.props in the same directory as
            // this program. It will contain default values for the various
            // parameters needed to connect to a database
            Properties p = new Properties();
            try {
                p.load(GetDBInfo.class.getResourceAsStream("DB.props"));
            } catch (Exception e) {
            }

            // Get default values from the properties file
            String driver = p.getProperty("driver"); // Driver class name
            String server = p.getProperty("server", ""); // JDBC URL for server
            String user = p.getProperty("user", ""); // db user name
            String password = p.getProperty("password", ""); // db password

            // These variables don't have defaults
            String database = null; // The db name (appended to server URL)
            String table = null; // The optional name of a table in the db

            // Parse the command-line args to override the default values above
            for (int i = 0; i < args.length; i++) {
                if (args[i].equals("-d"))
                    driver = args[++i]; //-d <driver>
                else if (args[i].equals("-s"))
                    server = args[++i];//-s <server>
                else if (args[i].equals("-u"))
                    user = args[++i]; //-u <user>
                else if (args[i].equals("-p"))
                    password = args[++i];
                else if (database == null)
                    database = args[i]; // <dbname>
                else if (table == null)
                    table = args[i]; // <table>
                else
                    throw new IllegalArgumentException("Unknown argument: " + args[i]);
            }

            // Make sure that at least a server or a database were specified.
            // If not, we have no idea what to connect to, and cannot continue.
            if ((server.length() == 0) && (database.length() == 0))
                throw new IllegalArgumentException("No database specified.");

            // Load the db driver, if any was specified.
            if (driver != null)
                Class.forName(driver);

            // Now attempt to open a connection to the specified database on
            // the specified server, using the specified name and password
            c = DriverManager.getConnection(server + database, user, password);

            // Get the DatabaseMetaData object for the connection. This is the
            // object that will return us all the data we're interested in here
            DatabaseMetaData md = c.getMetaData();

            // Display information about the server, the driver, etc.
            System.out.println("DBMS: " + md.getDatabaseProductName() + " " + md.getDatabaseProductVersion());
            System.out.println("JDBC Driver: " + md.getDriverName() + " " + md.getDriverVersion());
            System.out.println("Database: " + md.getURL());
            System.out.println("User: " + md.getUserName());

            // Now, if the user did not specify a table, then display a list of
            // all tables defined in the named database. Note that tables are
            // returned in a ResultSet, just like query results are.
            if (table == null) {
                System.out.println("Tables:");
                ResultSet r = md.getTables("", "", "%", null);
                while (r.next())
                    System.out.println("\t" + r.getString(3));
            }

            // Otherwise, list all columns of the specified table.
            // Again, information about the columns is returned in a ResultSet
            else {
                System.out.println("Columns of " + table + ": ");
                ResultSet r = md.getColumns("", "", table, "%");
                while (r.next())
                    System.out.println("\t" + r.getString(4) + " : " + r.getString(6));
            }
        }
        // Print an error message if anything goes wrong.
        catch (Exception e) {
            System.err.println(e);
            if (e instanceof SQLException)
                System.err.println(((SQLException) e).getSQLState());
            System.err.println("Usage: java GetDBInfo [-d <driver] " + "[-s <dbserver>]\n"
                    + "\t[-u <username>] [-p <password>] <dbname>");
        }
        // Always remember to close the Connection object when we're done!
        finally {
            try {
                c.close();
            } catch (Exception e) {
            }
        }
    }
}