建造者模式

當我們思考通過複雜的零件來生成一個完整的產品時，就用到了今天要說的主題-建造者模式，下面我們實際的程式碼來分析建造者模式的設計

假設飛機起飛需要有多個步驟，但是每種型號的飛機起飛的步驟又不相同，這時我們想要建造一個可以起飛多種型號飛機的工程。

1.首先我們先預先定義一個抽象的飛機起飛類，此類中包含啟動發動機、輪滑、推力式發射、彈射、起飛等操作。

public abstract class Airplane {

	//定義每個步驟的執行順序

	private ArrayList<String> sequence = new ArrayList<>();

	//飛機開啟發動機
 

	protected abstract void start();

	//飛機滑行

	protected abstract void glide();

	//飛機被推力發射

	protected abstract void emit();

	//飛機彈射

	protected abstract void popup();

	//開始起飛

	protected abstract void hopoff();

	//設定傳遞方法

	final public void setSequence(ArrayList<String> sequence) {

		this.sequence = sequence;
 

	}

	//飛機起飛步驟

	final public void run() {

		for(int i = 0;i<this.sequence.size();i++) {

			String actionName = this.sequence.get(i);

			if(actionName.equalsIgnoreCase("start")) {

				this.start();

			}else if(actionName.equalsIgnoreCase("glide")) {

				this.glide();

			}else if(actionName.equalsIgnoreCase("emit")) {
 

				this.emit();

			}else if(actionName.equalsIgnoreCase("popup")) {

				this.popup();

			}else if(actionName.equalsIgnoreCase("hopoff")) {

				this.hopoff();

			}

		}

	}

}

class J10 extends Airplane{

	@Override

	protected void start() {

		// TODO Auto-generated method stub

		System.out.println("J10啟動發動機");

	}

	@Override

	protected void glide() {

		// TODO Auto-generated method stub

		System.out.println("J10開始滑行");

	}

	@Override

	protected void emit() {

		// TODO Auto-generated method stub

		System.out.println("J10被髮射");

	}

	@Override

	protected void popup() {

		// TODO Auto-generated method stub

		System.out.println("J10被彈射");

	}

	@Override

	protected void hopoff() {

		// TODO Auto-generated method stub

		System.out.println("J10成功起飛");

	}

}

class J15 extends Airplane{

	@Override

	protected void start() {

		// TODO Auto-generated method stub

		System.out.println("J15啟動發動機");

	}

	@Override

	protected void glide() {

		// TODO Auto-generated method stub

		System.out.println("J15開始滑行");

	}

	@Override

	protected void emit() {

		// TODO Auto-generated method stub

		System.out.println("J15被髮射");

	}

	@Override

	protected void popup() {

		// TODO Auto-generated method stub

		System.out.println("J15被彈射");

	}

	@Override

	protected void hopoff() {

		// TODO Auto-generated method stub

		System.out.println("J15成功起飛");

	}

}

2.定義建造類-定義每種型別飛機的起飛步驟

/**

 * 飛機組裝類

 *

 */

public abstract class AirBuilder {

	public abstract void setSequence(ArrayList<String> sequence);

	//設定飛機的不同型號

	public abstract Airplane getAirplane();

}

class J10Builder extends AirBuilder{

	private J10 j10 = new J10();

	@Override

	public void setSequence(ArrayList<String> sequence) {

		// TODO Auto-generated method stub

		this.j10.setSequence(sequence);

	}

	@Override

	public Airplane getAirplane() {

		// TODO Auto-generated method stub

		return this.j10;

	}

}

class J15Builder extends AirBuilder{

	private J15 j15 = new J15();

	@Override

	public void setSequence(ArrayList<String> sequence) {

		// TODO Auto-generated method stub

		this.j15.setSequence(sequence);

	}

	@Override

	public Airplane getAirplane() {

		// TODO Auto-generated method stub

		return this.j15;

	}

}

3.開始起飛測試

/**

 * 飛行測試

 *

 */

public class Client {

	public static void main(String[] args) {

		// TODO Auto-generated method stub

       ArrayList<String> sequence1 = new ArrayList<>();

       sequence1.add("start");//設定J10開始發動

       sequence1.add("glide");//開始滑行

       sequence1.add("hopoff");//成功起飛

       ArrayList<String> sequence2 = new ArrayList<>();

       sequence2.add("start");//設定J150開始發動

       sequence2.add("emit");//開始彈射

       sequence2.add("hopoff");//成功起飛

       //例項化一架J10

       J10Builder j10builder = new J10Builder();

       j10builder.setSequence(sequence1);

       J10 j10 = (J10) j10builder.getAirplane();

       j10.run();

       System.out.println();

       J15Builder j15Builder = new J15Builder();

       j15Builder.setSequence(sequence2);

       J15 j15 = (J15) j15Builder.getAirplane();

       j15.run();

	}

}

執行結果：

批量建造

/**

 * 飛機場-定義每種型號飛機的具體起飛方法

 */

public class AirPort {

	private ArrayList<String> sequence = new ArrayList<>();//定義起飛步驟順序

	private J10Builder j10builder = new J10Builder();

	private J15Builder j15builder = new J15Builder();

	/**

	 * 定義J10起飛步驟

	 * @return J10

	 */

	public J10 getJ10model() {

		this.sequence.clear();

		sequence.add("start");//設定J10開始發動

	    sequence.add("glide");//開始滑行

	    sequence.add("hopoff");//成功起飛

	    this.j10builder.setSequence(sequence);

	    return (J10)this.j10builder.getAirplane();

	}

	/**

	 * 定義J150起飛步驟

	 * @return J15

	 */

	public J15 getJ15model() {

		this.sequence.clear();

		sequence.add("start");//設定J15開始發動

	    sequence.add("emit");//彈射

	    sequence.add("hopoff");//成功起飛

	    this.j15builder.setSequence(sequence);

	    return (J15)this.j15builder.getAirplane();

	}

}

定義測試類

public class NewClient {

	public static void main(String[] args) {

		AirPort airport = new AirPort();

		for (int i = 0; i<=20; i++) {

			System.out.println("第"+i+"架J10開始起飛");

			airport.getJ10model().run();

		}

		for (int i = 0; i<=30; i++) {

			System.out.println("第"+i+"架J15開始起飛");

			airport.getJ15model().run();

		}

	}

}

執行結果：

以上程式碼可以細細品味這樣設計的好處，建造者模式便於我們控制細節，並且使得程式容易擴充套件。