Loading Driver Class Automatically

JDBC for SQL Server - Herong's Tutorial Examples

∟Loading Driver Class Automatically

This section provides a tutorial program to show how JDK 1.7 and 1.8 automatically loads JDBC driver classes from JAR files specified in the classpath.

If you are using newer versions of JDK, the JDBC driver will be loaded automatically from the JAR file provided in the classpath. Here is an example program that you can use to list all JDBC drivers (driver classes):

/* ListDrivers.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.*;
import java.util.*;
public class ListDrivers {
  public static void main(String [] args) {
    try {
      printDrivers();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  private static void printDrivers() {
    Enumeration driverList = DriverManager.getDrivers();
    System.out.println("\nList of drivers:");
    while (driverList.hasMoreElements()) {
      Driver driverClass = (Driver) driverList.nextElement();
      System.out.println("   "+driverClass.getClass().getName());
    }
  }
}

Compile and run the above program with the JDBC Driver JAR file included in the current directory. By the way, the classpath delimiter is ":" on macOS and Linux systems. For Windows systems, you need to use ";".

herong> java -version
java version "17.0.1" 2021-10-19 LTS

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar ListDrivers.java
List of drivers:
   com.microsoft.sqlserver.jdbc.SQLServerDriver

Test results of older JDBC Driver versions are listed below:

Test 1 - Run the example program with JDK 1.8 and JDBC Driver 4.2 JAR file specified in the classpath:

herong> javac ListDrivers.java

herong> java ListDrivers -cp .;\local\lib\sqljdbc42.jar ListDrivers

List of drivers:
   com.microsoft.sqlserver.jdbc.SQLServerDriver

Test 2 - Run the example program with JDK 1.7 and JDBC Driver 4.2 JAR file specified in the classpath:

herong> javac ListDrivers.java

herong> java -cp .;\local\lib\sqljdbc42.jar ListDrivers

List of drivers:
   sun.jdbc.odbc.JdbcOdbcDriver

Test 3 - Run the example program with JDK 1.7 and JDBC Driver 4.1 JAR file specified in the classpath:

herong> javac ListDrivers.java

herong> java -cp .;\local\lib\sqljdbc41.jar ListDrivers

List of drivers:
   sun.jdbc.odbc.JdbcOdbcDriver
   com.microsoft.sqlserver.jdbc.SQLServerDriver

If you are confused with these tests, see my explanations below:

"SQLServerDriver" is showing in the output of Test 1, because the specified sqljdbc4.2 JAR file is compatible with JDK 1.8.
"JdbcOdbcDriver" is not showing in the output of Test 1, because the JDBC-ODBC Bridge driver is no longer included in JDK 1.8.
"SQLServerDriver" is not showing in the output of Test 2, because the specified sqljdbc4.2 JAR file is not compatible with JDK 1.7.
"JdbcOdbcDriver" is showing in the output of Test 2, because the JDBC-ODBC Bridge driver is included in JDK 1.7.
"SQLServerDriver" is showing in the output of Test 3, because the specified sqljdbc4.1 JAR file is compatible with JDK 1.7.