用桥接模式实现在路上开车这个问题，其中，车可以是car或bus，路可以是水泥路或沥青路。

源码：

//Road.java
package shiyan9;

public abstract class Road {
protected Vehicle vehicle;
public void setVehicle(Vehicle ve) {
this.vehicle=ve;
}
public abstract void drive();
}
//Shuini.java
package shiyan9;

public class Shuini extends Road{
public void drive() {
vehicle.run();
System.out.println("行驶在水泥路");
}
}
//Liqing.java
package shiyan9;

public class liqing extends Road{
public void drive() {
vehicle.run();
System.out.println("行驶在沥青路");
}
}
//Vehicle.java
package shiyan9;

public interface Vehicle {
public void run();
}
//Bus.java
package shiyan9;

public class Bus implements Vehicle{
@Override
public void run() {
System.out.print("Bus");
}
}
//Car.java
package shiyan9;

public class Car implements Vehicle{
@Override
public void run() {
System.out.print("Car");
}
}
//Main.java
package shiyan9;

import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Vehicle vehicle = null;
Road road = null;
System.out.println("请选择：1、Car/水泥路 2、Car/沥青路 3、Bus/水泥路 4、Bus/沥青路");
Scanner input=new Scanner(System.in);
int i=input.nextInt();
if(i==1) {
vehicle=(Vehicle)new Car();
road=(Road)new Shuini();
}else if(i==2) {
vehicle=(Vehicle)new Car();
road=(Road)new liqing();
}else if(i==3){
vehicle=(Vehicle)new Bus();
road=(Road)new Shuini();
}else if(i==4) {
vehicle=(Vehicle)new Bus();
road=(Road)new liqing();
}else {
System.out.println("输入无效！");
}
road.setVehicle(vehicle);
road.drive();
}
}