1         Class.forName("com.mysql.jdbc.Driver");
2         Connection conn = DriverManager.getConnection(
3                 "jdbc:mysql://localhost:3306/test", "root", "123456");
4         Statement stmt = conn.createStatement();
5
6         ResultSet rs = stmt.executeQuery("select * from Users");

 1 public class Program {
 2
 3     public static void main(String[] args) throws InstantiationException,
 4             IllegalAccessException, ClassNotFoundException {
 5         Class.forName("SpiA");
 6
 7         Api api = new Api("a");
 8         api.Send("段光伟");
 9     }
10 }

 1 import java.util.*;
 2
 3 public class Api {
 4     private static HashMap<String, Class<? extends Spi>> spis = new HashMap<String, Class<? extends Spi>>();
 5     private String protocol;
 6
 7     public Api(String protocol) {
 8         this.protocol = protocol;
 9     }
10
11     public void Send(String msg) throws InstantiationException,
12             IllegalAccessException {
13         Spi spi = spis.get(protocol).newInstance();
14
15         spi.send("消息发送开始");
16         spi.send(msg);
17         spi.send("消息发送结束");
18     }
19
20     public static void Register(String protocol, Class<? extends Spi> cls) {
21         spis.put(protocol, cls);
22     }
23 }

1 public interface Spi {
2     void send(String msg);
3 }

 1 public class SpiA implements Spi {
 2     static {
 3         Api.Register("a", SpiA.class);
 4     }
 5
 6     @Override
 7     public void send(String msg) {
 8         System.out.println("SpiA：" + msg);
 9     }
10
11 }