建造者模式(Builder Pattern)：将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。

实例

以构建Dialog为例，一般Dialog中包含Dialog标题，Dialog内容，Dialog确认按钮，Dialog取消按钮。

image.png

Dialog类

public class Dialog {
    private String title;
    private String content;
    private String button1;
    private String button2;

    public void setTitle(String title){
        this.title = title;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public void setNegativeButton(String button) {
        this.button1 = button;
    }

    public void setPositiveButton(String button) {
        this.button2 = button;
    }

    @Override
    public String toString() {
        return "Dialog{" +
                "title='" + title + '\'' +
                ", content='" + content + '\'' +
                ", button1='" + button1 + '\'' +
                ", button2='" + button2 + '\'' +
                '}';
    }
}

DialogBuilder为一个抽象的构建器

public abstract class AbstractDialogBuilder {
    protected Dialog dialog;

    public Dialog getDialog() {
        return dialog;
    }

    public void createDialog(){
        dialog = new Dialog();
    }


    public abstract void setTitle(String title);
    public abstract void setContent(String content);
    public abstract void setNegativeButton(String button);
    public abstract void setPositiveButton(String button);

}

public class DialogBuilder extends AbstractDialogBuilder {
    
    @Override
    public void setTitle(String title) {
        dialog.setTitle(title);
    }

    @Override
    public void setContent(String content) {
        dialog.setContent(content);
    }

    @Override
    public void setNegativeButton(String button) {
        dialog.setNegativeButton(button);
    }

    @Override
    public void setPositiveButton(String button) {
        dialog.setPositiveButton(button);
    }
}

测试

public class Test {
    public static void main(String[] args) {
        DialogBuilder builder = new AlertDialogDialogBuilder();
        builder.createDialog();
        builder.setTitle("title");
        builder.setContent("content");
        builder.setNegativeButton("negativeButton");
        builder.setPositiveButton("positiveButton");

        Dialog dialog = builder.getDialog();

        System.out.println(dialog.toString());;
    }

}

输出

Dialog{title='title', content='content', button1='negativeButton', button2='positiveButton'}