设计模式系列之三：建造者模式

建造者，顾名思义，就是要从设计师的角度去建造一个产品，就像你造一个汽车，一部手机，这时候我们首先就需要众多零件，这些零件就是你所需要的类，同时还要合理的把这些零件组装带一起产生一个你需要的产品。

建造者模式的本质是分离了对象自组建的单独构造（由Builder来负责）和装配（由Director来负责），从而可以构造出复杂的对象。由于实现了构造和装配的解耦，不同的构造器，相同的装配过程也会产生不同的结果，不同的装配顺序也会产生不同的结果。

以制造手机为例，现在我们需要的零件（类）有主板，摄像机，屏幕

package com.panda.build;

public class Phone {
private Camera camera;
private Screen screen;
private Mainboard mainboard;
public Phone(Camera camera, Screen screen, Mainboard mainboard) {
super();
this.camera = camera;
this.screen = screen;
this.mainboard = mainboard;
}
public Phone() {
super();
// TODO Auto-generated constructor stub
}
public Camera getCamera() {
return camera;
}
public void setCamera(Camera camera) {
this.camera = camera;
}
public Screen getScreen() {
return screen;
}
public void setScreen(Screen screen) {
this.screen = screen;
}
public Mainboard getMainboard() {
return mainboard;
}
public void setMainboard(Mainboard mainboard) {
this.mainboard = mainboard;
}
}

class Camera{
private String name;

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

public String getName() {
return name;
}

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

}
class Screen{
private String name;

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

public String getName() {
return name;
}

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

}
class Mainboard{
private String anme;

public Mainboard(String anme) {
super();
this.anme = anme;
}

public String getAnme() {
return anme;
}

public void setAnme(String anme) {
this.anme = anme;
}

}
一个构造器接口和实现类

package com.panda.build;

public interface PhoneBuilder {
Camera getCamera();
Screen getScreen();
Mainboard getMainboard();
}

package com.panda.build;

public class PhoneBuilderImpl implements PhoneBuilder{

@Override
public Camera getCamera() {
Camera c = new Camera("莱卡");
return c;
}

@Override
public Screen getScreen() {
Screen s = new Screen("飞利浦");
return s;
}

@Override
public Mainboard getMainboard() {
Mainboard m = new Mainboard("华为");
return m;
}

}

一个装配器接口和实现类
package com.panda.build;

public interface PhoneDirector {
Phone getPhone();
}

package com.panda.build;

public class PhoneDirectorImpl implements PhoneDirector{
private PhoneBuilder pBuilder;

public PhoneDirectorImpl(PhoneBuilder pBuilder) {
super();
this.pBuilder = pBuilder;
}

@Override
public Phone getPhone() {
Phone phone = new Phone();
phone.setCamera(pBuilder.getCamera());
phone.setScreen(pBuilder.getScreen());
phone.setMainboard(pBuilder.getMainboard());
return phone;
}
}

然后进行测试
package com.panda.build;

public class TestPhone {
public static void main(String[] args) {
Phone phone = new PhoneDirectorImpl(new PhoneBuilderImpl()).getPhone();
phone.getCamera();
System.out.println(phone.getCamera().getName());
}
}

结果：