谈谈我对Builder建造者模式的想法

首先，我们先看Builder建造者模式的UML图！！！

对着别人代码也敲了下，我们先来看看，也许你也会有点感触。

对着上面的UML图，我们可以对着敲出以下代码：

public class MacBook extends Computer {    protected MacBook() {    }    @Override    public void setmOs() {    }}abstract class Computer {    protected String mBorad;    protected String mDisplay;    protected String mOs;    public Computer() {    }    public void setmBorad(String mBorad) {        this.mBorad = mBorad;    }    public void setmDisplay(String mDisplay) {        this.mDisplay = mDisplay;    }    public abstract void setmOs();    @Override    public String toString() {        return "Computer{" +                "mBorad='" + mBorad + '\'' +                ", mDisplay='" + mDisplay + '\'' +                ", mOs='" + mOs + '\'' +                '}';    }}abstract class Builder {    public abstract void buildBroad(String broad);    public abstract void buildDisplay(String display);    public abstract void buildOs();    public abstract Computer create();}class MacBookBuilder extends Builder {    private Computer mcomputer = new MacBook();    @Override    public void buildBroad(String broad) {        mcomputer.setmBorad(broad);    }    @Override    public void buildDisplay(String display) {        mcomputer.setmDisplay(display);    }    @Override    public void buildOs() {        mcomputer.setmOs();    }    @Override    public Computer create() {        return mcomputer;    }}class Director {    Builder builder = null;    public Director(Builder builder) {        this.builder = builder;    }    public void construct(String broad, String dispaly) {        builder.buildBroad(broad);        builder.buildDisplay(dispaly);        builder.buildOs();    }}

上面我们对着UML敲了个例子，但是我们知道接口和抽象类实际的效果是一样的都是解耦

我们又可以这样写！

代码如下：

public class MacBook implements Computer {    private String Borad;    private String Display;    private String Os;    protected MacBook() {    }    @Override    public void setmBorad(String Borad) {        this.Borad = Borad;    }    @Override    public void setmDisplay(String Display) {        this.Display = Display;    }    @Override    public void setmOs() {    }}interface Computer {    void setmBorad(String Borad);    void setmDisplay(String Display);    void setmOs();}interface Builder {    void buildBroad(String broad);    void buildDisplay(String display);    void buildOs();    Computer create();}class MacBookBuilder implements Builder {    private Computer mcomputer = new MacBook();    @Override    public void buildBroad(String broad) {        mcomputer.setmBorad(broad);    }    @Override    public void buildDisplay(String display) {        mcomputer.setmDisplay(display);    }    @Override    public void buildOs() {        mcomputer.setmOs();    }    @Override    public Computer create() {        return mcomputer;    }}class Director {    Builder builder = null;    public Director(Builder builder) {        this.builder = builder;    }    public void construct(String broad, String dispaly) {        builder.buildBroad(broad);        builder.buildDisplay(dispaly);        builder.buildOs();    }}

用接口和抽象类，总感觉有点不舒服，看起来不是那么直观，记得alertdialog是一段.set(),链式的结构。

那我们模仿alertdialog写写，我的感触是他并没有像UML那样划分的很细致。

如果我们把接口和抽象类全部去掉，代码会是怎么样？

代码如下：

public class MacBook   {    private String Borad;    private String Display;    private String Os;    protected MacBook() {    }    public void setmBorad(String Borad) {        this.Borad = Borad;    }    public void setmDisplay(String Display) {        this.Display = Display;    }    public void setmOs() {    }}class MacBookBuilder  {    private MacBook mcomputer = new MacBook();    public void buildBroad(String broad) {        mcomputer.setmBorad(broad);    }    public void buildDisplay(String display) {        mcomputer.setmDisplay(display);    }    public void buildOs() {        mcomputer.setmOs();    }    public MacBook create() {        return mcomputer;    }}class Director {    MacBookBuilder builder = null;    public Director(MacBookBuilder builder) {        this.builder = builder;    }    public void construct(String broad, String dispaly) {        builder.buildBroad(broad);        builder.buildDisplay(dispaly);        builder.buildOs();    }}

咦，貌似有那么点意思了。

最后有个类Director,用的好像就是一段set的链式结构

模仿AlertDialog它有两种生成对象的方式：

1.Builder

它是通过类似链式结构的形式创建

2.alertdialog对象

它是通过类似创建类对象的形式创建

OK,思路：1.我们就可以把Director这个导向类，放入类中，2.Builder中创建类对象返回对象3.通过各自的构造函数传递值

我们试一试！

public class MacBook   {     String Borad;     String Display;     String Os;    MacBookBuilder builder = new MacBookBuilder(this);    protected MacBook(MacBookBuilder builder) {        this.Borad=builder.Borad;        this.Display=builder.Display;        this.Os=builder.Os;    }    public void setmBorad(String Borad) {        this.Borad = Borad;    }    public void setmDisplay(String Display) {        this.Display = Display;    }    public void setmOs() {    }    public void construct(String broad, String dispaly) {        builder.buildBroad(broad);        builder.buildDisplay(dispaly);        builder.buildOs();    }}class MacBookBuilder  {     String Borad;     String Display;     String Os;    MacBookBuilder(MacBook macBook){    }    MacBook macBook = new MacBook(this);    public MacBookBuilder buildBroad(String broad) {        macBook.setmBorad(broad);        return this;    }    public MacBookBuilder buildDisplay(String display) {        macBook.setmDisplay(display);        return this;    }    public MacBookBuilder buildOs() {        macBook.setmOs();        return this;    }    public MacBook create() {        return macBook;    }}

虽然，我不是处女座。就像卖牛奶的广告一样 没有最好，只有更好

我们需要加工下！！！

代码如下：

public class MacBook   {     String Borad;     String Display;     String Os;    protected MacBook(MacBookBuilder builder) {        this.Borad=builder.Borad;        this.Display=builder.Display;        this.Os=builder.Os;    }    public String setmBorad(String Borad) {        this.Borad = Borad;        return Borad;    }    public String setmDisplay(String Display) {        this.Display = Display;        return Display;    }    public String setmOs() {        this.Os="ubuntu";        return Os;    }    public MacBookBuilder construct() {        return new MacBookBuilder(this);    }}class MacBookBuilder  {     String Borad;     String Display;     String Os;    MacBookBuilder(MacBook macBook){        this.Borad=macBook.Borad;        this.Display=macBook.Display;        this.Os=macBook.Os;    }    public MacBookBuilder buildBroad(String broad) {        this.Borad = broad;        return this;    }    public MacBookBuilder buildDisplay(String display) {        this.Display = display;        return this;    }    public MacBookBuilder buildOs() {        this.Os = "";        return this;    }    public MacBook create() {        return new MacBook(this);    }}

再次更好！

代码：

public class MacBook {    String Borad;    String Display;    String Os;    protected MacBook(MacBookBuilder builder) {        this.Borad = builder.Borad;        this.Display = builder.Display;        this.Os = builder.Os;    }    public String setmBorad(String Borad) {        this.Borad = Borad;        return Borad;    }    public String setmDisplay(String Display) {        this.Display = Display;        return Display;    }    public String setmOs() {        this.Os = "ubuntu";        return Os;    }    public MacBookBuilder construct() {        return new MacBookBuilder(this);    }    static class MacBookBuilder {        String Borad;        String Display;        String Os;        MacBookBuilder(MacBook macBook) {            this.Borad = macBook.Borad;            this.Display = macBook.Display;            this.Os = macBook.Os;        }        public MacBookBuilder buildBroad(String broad) {            this.Borad = broad;            return this;        }        public MacBookBuilder buildDisplay(String display) {            this.Display = display;            return this;        }        public MacBookBuilder buildOs() {            this.Os = "";            return this;        }        public MacBook create() {            return new MacBook(this);        }    }}

总结：

1.在什么时候使用建造者模式？

就比如android上创建订单，类的字段比较多

2.建造者模式有什么好处？

我认为是更好的展现多态吧。用链式的set对对象字段设置，我想要什么特性就有什么特性。

3.那怎么创建自己的建造者模式？

我自己想了个想法。我要在一片空地造房子，我可以自己买材料装修，也能自己包给别人来做。（小弟不才，忘大佬们指点指点。）