创建者模式Builder

创建者模式：

     分离对象子组件的单独构造(由Builder来负责)和装配(由Director负责)，对象的构造比较复杂时使用 该模式。

类图：

Builder 抽象建造者接口，规范各个组成部分的构建。

　　ConcreteBuilder 具体建造者角色，实现组成部分的构建，并提供示例。

　　Product 产品角色，创建返回的对象。

　　Director 导演者角色，负责创建以及使用。

优点：

      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成不同的对象，相同的构建器，不同的装配顺序也可以生产成不同的对象。也就是实现了构造算法和装配算法的解耦，实现了更好的复用。

应用场景：

    StringBuilder类的append方法。

    SQL中的PreparedStatement

    JDOM中，DomBuilder SAXBuilder

创建者模式Demo

package builder.domain;

/**
 * 宇宙飞船
 *
 */
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;
    }
}


package builder.domain;

public 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;
    }
}


package builder.domain;

public 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;
    }
}


package builder.domain;

public 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;
    }
    
    
}


package builder.service;

import builder.domain.Engine;
import builder.domain.EscapeTower;
import builder.domain.OrbitalModule;

public interface IAirShipBuilder {
    Engine builderEngine();
    OrbitalModule builderOrbitalModule();
    EscapeTower  builderEscapeTower();
}


package builder.service;

import builder.domain.Engine;
import builder.domain.EscapeTower;
import builder.domain.OrbitalModule;

public class AirShipBuilderImpl implements IAirShipBuilder {
    //StringBuilder, 以后学习XML解析中，JDOM库中的类：DomBuilder,SaxBuilder
    @Override
    public Engine builderEngine() {
        // TODO Auto-generated method stub
        System.out.println("构建发动机！");
        return new Engine("发动机！");
    }

    @Override
    public OrbitalModule builderOrbitalModule() {
        // TODO Auto-generated method stub
        System.out.println("构建轨道舱");
        return new OrbitalModule("轨道舱");
    }

    @Override
    public EscapeTower builderEscapeTower() {
        // TODO Auto-generated method stub
        System.out.println("构建逃逸塔");
        return new EscapeTower("逃逸塔");
    }

}


package builder;

import builder.domain.AirShip;

public interface IAirShipDirector {
    /**
     * 组装飞船对象
     * @return
     */
    AirShip   directAirShip();
}


package builder;

import builder.domain.AirShip;
import builder.domain.Engine;
import builder.domain.EscapeTower;
import builder.domain.OrbitalModule;
import builder.service.IAirShipBuilder;

public class AirshipDirectorImpl implements IAirShipDirector {
    private IAirShipBuilder builder;
    
    public AirshipDirectorImpl(IAirShipBuilder builder) {
        this.builder = builder;
    }
    
    @Override
    public AirShip directAirShip() {
        // TODO Auto-generated method stub
        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;
    }

}

package builder;

import builder.domain.AirShip;
import builder.service.AirShipBuilderImpl;

public class Client {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        IAirShipDirector director = new AirshipDirectorImpl(new AirShipBuilderImpl());

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

}