jdbc_rs_metadata.java

有关JDBC的使用一些编程实例,有关与数据库连接的代码

/*
 Copyright 1996 John Wiley & Sons, Inc. All Rights Reserved. Reproduction
 or translation of this work beyond that permitted in Section 117 of the 1976
 United States Copyright Act without the express written permission of the
 copyright owner is unlawful. Requests for further information should be 
 addressed to Permissions Department, John Wiley & Sons, Inc. The 
 purchaser may make back-up copies for his/her own use only and not for 
 distribution or resale. The Publisher assumes no responsibility for errors, 
 omissions, or damages, caused by the use of this  software or from the use
 of the information contained herein.
*/

import java.util.*;
import java.net.URL;
import java.sql.*;

class jdbc_rs_metadata {

  public static void main(String argv[]) {

    // the url comes in from argv[0], so
    // error out if there was no url passed
    //
    if (argv.length == 0) {
      System.err.println("Usage:");
      System.err.println("");
      System.err.println("java jdbc_connect URL");
      System.exit(1);
    }

    try {

      // register all of the JDBC classes you might use
      // you can comment out or remove the ones you
      // are not using.
      //
      Class.forName("textFileDriver").newInstance();               // the tinySQL textFile driver
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance(); // JDBC-ODBC bridge
      Class.forName("com.sybase.jdbc.SybDriver").newInstance();    // Sybase
      Class.forName("com.imaginary.sql.msql.MsqlDriver").newInstance();    // mSQL

      String url = argv[0];

      // the user might have passed in a user name or password,
      // so try to read those in, as well
      //
      String user, pwd;
      if (argv.length > 1) {
        user = argv[1];
      } else {
        user = "";
      }
      if (argv.length > 2) {
        pwd = argv[2];
      } else {
        pwd = "";
      }

      // make a connection to the specified URL
      //
      Connection con = DriverManager.getConnection(url, user, pwd);
   
      // get a Statement object from the Connection
      //
      Statement stmt = con.createStatement();

      // Execute a query and get the result set
      //
      ResultSet rs = stmt.executeQuery("SELECT name, id FROM test");

      // 
      //
      ResultSetMetaData meta = rs.getMetaData();

      int numcols = meta.getColumnCount();


      stmt.close();
      con.close();

      System.out.println("Column count was: " + numcols);

    }
    catch( Exception e ) {
      System.out.println(e.getMessage());
      e.printStackTrace();
    }
  }

}