我的博客：https://devallever.github.io/

定義

將一個復雜對象的構建與它的表示分離,使得同樣的構建過程可以創建不同的表示

你看懂了嗎? 反正我是一臉懵逼

UML類圖

解讀:

• Product產品類: 產品抽象類
• Builder: 抽象Builder類,規劃產品組建,一般是由子類實現具體的組建過程
• ConcreteBuilder: 具體的Builder類
• Director: 統一組建過程

好吧, 還是說的有點虛呀, 來一個簡單例子

簡單實現

Computer抽象類類：Product角色，即產品抽象類

/**
 * Created by allever on 17-5-18.
 * 計算機抽象類: Product角色*/

public abstract class Computer {

    private String strBoard;
    private String strDisplay;
    private String strOS;

    protected Computer(){}
    /**CPU核心數*/
    public void setBoard(String board){
        this.strBoard = board;
    }
    public void setDisplay(String display){
        this.strDisplay = display;
    }

    public void setStrOS(String os){
        this.strOS = os;
    }

    @Override
    public String toString() {
        String result = "Computer:\nboard=" + strBoard + "\ndisplay = " + strDisplay + "\nOS = " + strOS;
        return result;
    }
}

MacBook類，具體Computer類

/**
 * Created by allever on 17-5-18.
 */

public class MacBook extends Computer {
    protected MacBook(){}

}

Builder抽象類

負責規范產品組建，一般是由子類實現具體的組建過程

/**
 * Created by allever on 17-5-18.
 * 抽象Builder類*/

public abstract class Builder {
    public abstract void buildBoard(String board);
    public abstract void buildDisplay(String display);
    public abstract void buildOS(String os);
    public abstract Computer build();
}

MacBookBuilder：具體Builder類，ConcreteBuilder角色

/**
 * Created by allever on 17-5-18.
 * Builder實現類*/

public class MacBookBuilder extends Builder {

    private Computer computerMacBook = new MacBook();

    @Override
    public void buildBoard(String board) {
        computerMacBook.setBoard(board);
    }

    @Override
    public void buildDisplay(String display) {
        computerMacBook.setDisplay(display);
    }

    @Override
    public void buildOS(String os) {
        computerMacBook.setStrOS(os);
    }

    @Override
    public Computer build() {
        return computerMacBook;
    }
}

Director類：同一組裝過程

/**
 * Created by allever on 17-5-18.
 * Director類： 負責構建Computer*/

public class Director {
    private Builder builder = null;
    public Director(Builder builder){
        this.builder = builder;
    }

    //構建對象
    public void construct(String board, String display, String os){
        builder.buildBoard(board);
        builder.buildDisplay(display);
        builder.buildOS(os);

    }
}

客戶端調用

Builder builder = new MacBookBuilder();
Director director = new Director(builder);
director.construct("英特爾酷睿i7","15.6寸","Ubuntu 16.04");
Log.d(TAG, builder.build().toString());
Toast.makeText(BuildPatternsActivity.this,builder.build().toString(),Toast.LENGTH_LONG).show();

小提示

通常,Director角色會被省略,直接使用Builder構建對象,這個Builder通常為鏈式調用,即buildXXX()方法返回自身,return this;

修改后的Builder類

/**
 * Created by allever on 17-5-18.
 * 抽象Builder類*/

public abstract class Builder {
    public abstract Builder buildBoard(String board);
    public abstract Builder buildDisplay(String display);
    public abstract Builder buildOS(String os);
    public abstract Computer build();
}

MacBookBuilder:

/**
 * Created by allever on 17-5-18.
 * Builder實現類*/

public class MacBookBuilder extends Builder {

    private Computer computerMacBook = new MacBook();

    @Override
    public MacBookBuilder buildBoard(String board) {
        computerMacBook.setBoard(board);
        return this;
    }

    @Override
    public MacBookBuilder buildDisplay(String display) {
        computerMacBook.setDisplay(display);
        return this;
    }

    @Override
    public MacBookBuilder buildOS(String os) {
        computerMacBook.setStrOS(os);
        return this;
    }

    @Override
    public Computer build() {
        return computerMacBook;
    }
}

在客戶端中的調用

Builder builder = new MacBookBuilder();
//Director director = new Director(builder);
//director.construct("英特爾酷睿i7","15.6寸","Ubuntu 16.04");
Log.d(TAG, builder.buildBoard("英特爾酷睿i7")
                    .buildDisplay("15.6寸")
                    .buildOS("Max OS")
                    build().toString());

現在你是不是感覺到很熟悉的呢? 就像Android中構建一個Notification對象

                Notification notification = new NotificationCompat.Builder(this)
                        .setContentTitle("This is content title")
                        .setContentText("This is content text")
                        .setSmallIcon(R.mipmap.ic_launcher)
                        .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher))
                        .setWhen(System.currentTimeMillis())
                        //設置點擊行為
                        .setContentIntent(pendingIntent)
                        //點擊后消失
                        .setAutoCancel(true)
                        //設置聲音
                        .setSound(Uri.fromFile(new File("/system/media/audio/ringtones/Luna.ogg")))
                        //設置震動 震動1s 靜止1s 震動1s 要申明權限
                        .setVibrate(new long[]{0, 1000,1000,1000})
                        //設置呼吸燈閃爍
                        .setLights(Color.GREEN, 1000, 1000)
                        //設置默認
                        .setDefaults(NotificationCompat.DEFAULT_ALL)
                        //設置長文本
                        .setStyle(new NotificationCompat.BigTextStyle().bigText("An Activity is an application component that provides a screen with which users can interact in order to do something, such as dial the phone, take a photo, send an email, or view a map."))
                        //設置展開大圖,,設置了長文本會看不到
                        .setStyle(new NotificationCompat.BigPictureStyle().bigPicture(BitmapFactory.decodeResource(getResources(),R.mipmap.expensive)))
                        //設置通知重要程度
                        .setPriority(NotificationCompat.PRIORITY_MAX)
                        .build();