建造者模式

建造者模式:

建造模式的本质：
        分离了对象子组件的单独构造(由Builder来负责)和装配(由Director负责)。 从而可以构造出复杂的对象。

这个模式适用于：某个对象的构建过程复杂的情况下使用。
– 由于实现了构建和装配的解耦。不同的构建器，相同的装配，也可以做出不同的对象；相同的构建器，不同的装配顺序也可以做出不同的对象。也就是实现了构建算法、装配算法的解耦，实现了更好的复用。

建造者开发中应用场景：
    – StringBuilder类的append方法
    – SQL中的PreparedStatement – JDOM中，DomBuilder、SAXBuilder

建造者模式案例:

//轨道舱
class OrbitalModule{
	private String name;
    public OrbitalModule(String name) {
		this.name = name;
	}
    public String getName() {
		return name;
	}
    public void setName(String name) {
		this.name = name;
	}
}

//发动机
class Engine {
	private String name;

	public Engine(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
}

//逃生舱
class EscapeTower{
	private String name;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public EscapeTower(String name) {
		super();
		this.name = name;
	}
}

//飞船的三个组件
public class AirShip {
	
	private OrbitalModule orbitalModule;  //轨道舱
	private Engine engine; //发动机
	private EscapeTower escapeTower;  //逃逸塔
	
    public void launch(){
		System.out.println("发射！");
	}
	
    public OrbitalModule getOrbitalModule() {
		return orbitalModule;
	}
	public void setOrbitalModule(OrbitalModule orbitalModule) {
		this.orbitalModule = orbitalModule;
	}
	public Engine getEngine() {
		return engine;
	}
	public void setEngine(Engine engine) {
		this.engine = engine;
	}
	public EscapeTower getEscapeTower() {
		return escapeTower;
	}
	public void setEscapeTower(EscapeTower escapeTower) {
		this.escapeTower = escapeTower;
	}
}

//构建者(用来构造飞船的各个组件)
public interface AirShipBuilder {
	Engine builderEngine();
	OrbitalModule builderOrbitalModule();
	EscapeTower  builderEscapeTower();
}

//装配者（负责装配飞船）
public interface AirShipDirector {

	 //组装飞船对象
    AirShip   directAirShip();
}

//构建者实现类
public class MyAirShipBuilder implements AirShipBuilder {
	
	@Override
	public Engine builderEngine() {
		System.out.println("构建尚学堂牌发动机！");
		return new Engine("发动机！");
	}
    @Override
	public EscapeTower builderEscapeTower() {
		
		System.out.println("构建逃逸塔");
		return new EscapeTower("逃逸塔");
	}

	@Override
	public OrbitalModule builderOrbitalModule() {
		System.out.println("构建轨道舱");
		return new OrbitalModule("轨道舱");
	}	
}

/**
  *装配者实现类：思路:装配者通过构建者来构造子组件，然后在进行组装
  */
    
public class MyAirshipDirector implements AirShipDirector {

	private AirShipBuilder builder;

	public MyAirshipDirector(AirShipBuilder builder) {
		this.builder = builder;
	}


	@Override
	public AirShip directAirShip() {
		Engine e = builder.builderEngine();
		OrbitalModule o = builder.builderOrbitalModule();
		EscapeTower et = builder.builderEscapeTower();
		
		//装配成飞船对象
		AirShip ship = new AirShip();
		ship.setEngine(e);
		ship.setEscapeTower(et);
		ship.setOrbitalModule(o);
		
		return ship;
	}
}

public class Client {
	public static void main(String[] args) {
		
		AirShipDirector director = new MyAirshipDirector(new MyAirShipBuilder());

		AirShip ship = director.directAirShip();
		
		System.out.println(ship.getEngine().getName());
		
		ship.launch();
    }
}