当得到简单的对象的时候,使用工厂模式即可.

当得到复杂的对象,而且对象的一些属性需要繁琐配置的时候,使用建造者模式比较好.

这里以建造汽车为例,汽车的组件可以自由搭配.

package builder;

public class Car {
	private String engine;
	private String tire;
	private String door;
	private String seat;

	public void setEngine(String engine) {
		this.engine = engine;
	}

	public void setTire(String tire) {
		this.tire = tire;
	}

	public void setDoor(String door) {
		this.door = door;
	}

	public void setSeat(String seat) {
		this.seat = seat;
	}

	@Override
	public String toString() {
		return Car [engine= + engine + , tire= + tire + , door= + door + , seat= + seat + ];
	}

	public void show() {
		System.out.println(toString());
	}
}

package builder;

public class CarBuilder {

	private Car car = new Car();

	public CarBuilder addEngine(String engine) {
		car.setEngine(engine);
		return this;
	}

	public CarBuilder addTire(String tire) {
		car.setTire(tire);
		return this;
	}

	public CarBuilder addDoor(String door) {
		car.setDoor(door);
		return this;
	}

	public CarBuilder addSeat(String seat) {
		car.setSeat(seat);
		return this;
	}

	/**
	 * 先设置好汽车的核心组件,然后再调用该方法
	 */
	public Car build() {
		return car;
	}
}

package builder;

import org.junit.Test;

public class CarTest {

	@Test
	public void test() {
		Car car = new CarBuilder()//
				.addDoor(华丽的车门)//
				.addEngine(黄金的引擎)//
				.addSeat(舒适的座椅)//
				.addTire(耀眼的轮胎)//
				.build();
		car.show();
	}

}

这样类似的builder在android用到的很多,在一些框架的配置对象中,也能看到建造者模式的影子.