Java设计模式--生成器模式

Posted 2020-11-16 petewell

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将一个复杂对象的构建与它的表示分离，使同样的构建过程可以创建不同的表示。

Builder Pattern

Separate the construction of a complex object from its representation so that the same construction process can create different representations.

类图

技术图片

模式的结构与使用

生成器模式的结构中包括四个角色。

产品（Product）：具体生成器要构造的复杂对象。
抽象生成器（Abstract Builder）：抽象生成器是一个接口，该接口除了为创建一个Product对象的各个组件定义了若干个方法外，还定义返回Product对象的方法。
具体生成器（Concrete Builder）：实现Builder接口的类，具体生成器将实现Builder接口所定义的方法。
指挥者（Director）：指挥者是一个类，该类需含有Builder接口声明的变量。指挥者的职责是负责向用户提供具体生成器，即指挥者将请求具体生成器来构造用户所需要的Product对象，如果所请求的具体生成器成功地构造出Product对象，指挥者就可以让该具体生成器返回所构造的Product对象。

简单的例子

Product的抽象类PanelProduct.java

package Builder;
import javax.swing.*;
public class  extends JPanel {
	JButton button;
	JLabel label;
	JTextField textField;
}

抽象生成器Builder接口类Builder.java

package Builder;
import javax.swing.JPanel;
public interface Builder {
	public abstract void buildButton();
	public abstract void buildLabel();
	public abstract void buildTextField();
	public abstract JPanel getPanel();
}

ConcreteBuilder的实现类ConcreteBuilderOne.java

package Builder;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class ConcreteBuilderOne implements Builder {
	private PanelProduct panel;
	
	public ConcreteBuilderOne() {
		panel = new PanelProduct();
	}
	
	public void buildButton() {
		panel.button = new JButton("按钮");
	}
	
	public void buildLabel() {
		panel.label = new JLabel("标签");
	}
	
	public void buildTextField() {
		panel.textField = new JTextField("文本框");
	}
	
	public JPanel getPanel() {
		panel.add(panel.button);
		panel.add(panel.label);
		panel.add(panel.textField);
		return panel;
	}
}

ConcreteBuilder的实现类ConcreteBuilderTwo.java

package Builder;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class ConcreteBuilderTwo implements Builder {
	private PanelProduct panel;
	
	public ConcreteBuilderTwo() {
		panel = new PanelProduct();
	}
	
	public void buildButton() {
		panel.button = new JButton("button");
	}
	@Override
	public void buildLabel() {
		panel.label = new JLabel("label");
	}
	@Override
	public void buildTextField() {
		panel.textField = new JTextField("My文本框");
	}
	@Override
	public JPanel getPanel() {
		panel.add(panel.textField);
		panel.add(panel.label);
		panel.add(panel.button);
		return panel;
	}
}

指挥类Director.java

package Builder;
import javax.swing.JPanel;
public class Director {
	private Builder builder;
	public Director(Builder builder) {
		this.builder = builder;
	}
	
	public JPanel constructProduct() {
		builder.buildButton();
		builder.buildLabel();
		builder.buildTextField();
		JPanel product = builder.getPanel();
		return product;
	}
}

测试类Application.java

ppackage Builder;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Application {
	public static void main(String[] args) {
		Builder builder = new ConcreteBuilderOne();
		Director director = new Director(builder);
		JPanel panel = director.constructProduct();
		JFrame frameOne = new JFrame();
		frameOne.add(panel);
		frameOne.setBounds(12, 12, 200, 120);
		frameOne.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
		frameOne.setVisible(true);
		
		builder = new ConcreteBuilderTwo();
		director = new Director(builder);
		panel = director.constructProduct();
		JFrame frameTwo = new JFrame();
		frameTwo.add(panel);
		frameTwo.setBounds(212, 12, 200, 120);
		frameTwo.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
		frameTwo.setVisible(true);
	}
}