在Java中使用原型设计模式

今天让我们讨论另一个创新的设计模式-原型设计模式。

原型设计模式

该原型设计模式是23熟知的一个GoF的设计模式，这有助于我们复制现有的对象，而不是从头开始创建一个新的实例。
当我们需要创建一个类的多个实例并且每个实例具有几乎相同的状态或具有很小的差异时，将使用“原型”模式。
当直接创建实际对象时，根据其持有的资源和数据，创建原型非常昂贵，并且会花费时间，因此会使用“原型”模式。现有的原始对象充当原型，并包含对象的状态。新对象是原始对象的副本。
所述原型当对象来创建的类型是由原型实例，其被克隆到产生新的对象确定用于图案。
如有需要，我们可以自由更改新复制的对象中的值。
原型模式可以帮助我们节省昂贵的资源和时间，尤其是在对象创建非常繁琐且耗时的过程中。
在Java中，其中一个最好的方式，通过使用创建一个从现有的对象是对象的clone（）方法可克隆的接口。克隆是实现原型模式的最简单方法。

我们还可以使用Deep Copy 方法来实现Prototype接口。 Deep Copy -通过深度复制，我们通过复制原始对象的所有字段来创建对象。而且，如果原始对象包含其他对象作为字段，我们也将其复制。 Shallow Copy-通过浅复制，我们通过复制原始对象的所有字段来创建对象。但是，如果原始对象包含其他对象作为字段，我们将仅复制这些对象的引用，而不是复制完整的对象本身。
有两种方法可以实现原型模式
- 基本实施
- 原型注册表实施

基本实施基本实施

原型注册表实施

在该模式的原型注册表实现中，我们创建一个注册表类来缓存对象以进行原型制作。在其他世界中，我们使用原型收集和管理服务或类，使所有原型都可访问并可用于原型制作。缓存注册表的目的是在内存中维护原型就绪对象池。为了更好地理解这一点，让我们看一个几何形状的例子。我将示例保持相对简单，以将重点放在模式上。

首先让我们定义几个常见的枚举，在实现原型模式时，将在每种不同的方法中使用这些枚举。

在这里，颜色枚举的代码：

package org.trishinfotech.prototype;
public enum Color {
    RED, GREEN, BLUE, YELLOW, WHITE, BLACK, ORANGE, MAROON
}

在这里，是LinePattern枚举的代码。我们将使用这些线型绘制不同的几何形状。

package org.trishinfotech.prototype;
public enum LinePattern {
    SOLID, DASH, DOT, DOUBLE_DASH, DASH_SPACE
}

在这里，是FillPattern枚举的代码。我们将使用这些填充图案来绘制不同的几何形状。

package org.trishinfotech.prototype;
public enum FillPattern {
    SOLID, DASH, DOT, CHECKS, HEART;
}

使用原型设计模式的几何形状示例-深度复制方法 让我们定义ShapeStyle 类：

package org.trishinfotech.prototype.example1;

import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.LinePattern;

public class ShapeStyle {

    protected Color lineColor;
    protected LinePattern linePattern;
    protected double lineThickness;

    public ShapeStyle() {
        super();
    }

    // prototype or deep copy constructor
    public ShapeStyle(ShapeStyle shapeStyle) {
        this();
        System.out.println("Deep Copying ShapeStyle...");
        this.lineColor = shapeStyle.lineColor;
        this.linePattern = shapeStyle.linePattern;
        this.lineThickness = shapeStyle.lineThickness;
    }

    public Color getLineColor() {
        return lineColor;
    }

    public void setLineColor(Color lineColor) {
        this.lineColor = lineColor;
    }

    public LinePattern getLinePattern() {
        return linePattern;
    }

    public void setLinePattern(LinePattern linePattern) {
        this.linePattern = linePattern;
    }

    public double getLineThickness() {
        return lineThickness;
    }

    public void setLineThickness(double lineThickness) {
        this.lineThickness = lineThickness;

    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("lineColor=").append(lineColor).append(", linePattern=").append(linePattern)
                .append(", lineThickness=").append(lineThickness);
        return builder.toString();
    }
}

这是FillStyle 类的代码：

package org.trishinfotech.prototype.example1;

import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.FillPattern;

public class FillStyle {

    protected Color fillColor;
    protected FillPattern fillPattern;

    public FillStyle() {
        super();
    }

    // prototype or deep copy constructor
    public FillStyle(FillStyle fillStyle) {
        super();
        System.out.println("Deep Copying FillStyle...");
        this.fillColor = fillStyle.fillColor;
        this.fillPattern = fillStyle.fillPattern;

    }

    public Color getFillColor() {
        return fillColor;
    }

    public void setFillColor(Color fillColor) {
        this.fillColor = fillColor;
    }

    public FillPattern getFillPattern() {
        return fillPattern;
    }

    public void setFillPattern(FillPattern fillPattern) {

        this.fillPattern = fillPattern;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("fillColor=").append(fillColor).append(", fillPattern=").append(fillPattern);
        return builder.toString();
    }

}

Now, let's define the Shape abstract class.

package org.trishinfotech.prototype.example1;

public abstract class Shape {

    protected int x;
    protected int y;
    protected ShapeStyle shapeStyle;

    public Shape() {
        super();

    }

    // prototype or deep copy constructor
    public Shape(Shape shape) {
        this();
        System.out.println("Deep Copying Shape...");
        this.x = shape.x;
        this.y = shape.y;
        this.shapeStyle = new ShapeStyle(shape.shapeStyle);
    }

    abstract void draw();

    abstract String type();


    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public ShapeStyle getStyle() {
        return shapeStyle;
    }

    public void setStyle(ShapeStyle shapeStyle) {
        this.shapeStyle = shapeStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("x=").append(x).append(", y=").append(y).append(", ").append(shapeStyle);
        return builder.toString();
    }

}

Here's the code for Circle class:

package org.trishinfotech.prototype.example1;

public class Circle extends Shape {

    protected int radius;
    protected FillStyle fillStyle;

    public Circle() {
        super();
    }

    // prototype or deep copy constructor
    public Circle(Circle circle) {
        super(circle);
        System.out.println("Deep Copying Circle...");
        this.radius = circle.radius;
        ;
        this.fillStyle = new FillStyle(circle.fillStyle);
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Circle (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Circle";
    }

    public int getRadius() {
        return radius;
    }

    public void setRadius(int radius) {
        this.radius = radius;
    }

    public FillStyle getFillStyle() {
        return fillStyle;
    }

    public void setFillStyle(FillStyle fillStyle) {
        this.fillStyle = fillStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("radius=").append(radius).append(", ").append(fillStyle);
        return builder.toString();
    }

}

Here's the code for Line class:

package org.trishinfotech.prototype.example1;

public class Line extends Shape {

    protected int x1;
    protected int y1;

    public Line() {
        super();
    }

    // prototype or deep copy constructor
    public Line(Line line) {
        super(line);
        System.out.println("Deep Copying Line...");
        this.x1 = line.x1;
        this.y1 = line.y1;
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Line (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Line";
    }
    public int getX1() {
        return x1;
    }

    public void setX1(int x1) {
        this.x1 = x1;

    }

    public int getY1() {
        return y;

    }

    public void setY(int y1) {

        this.y1 = y1;

    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("x1=").append(x1).append(", y1=").append(y1);
        return builder.toString();

    }

}

Here's the code for Rectangle class:

package org.trishinfotech.prototype.example1;

public class Rectangle extends Shape {

    protected int length;
    protected int width;

    protected FillStyle fillStyle;
    public Rectangle() {
        super();
    }

    // prototype or deep copy constructor
    public Rectangle(Rectangle rectangle) {
        super(rectangle);
        System.out.println("Deep Copying Rectangle...");
        this.length = rectangle.length;
        this.width = rectangle.width;
        this.fillStyle = new FillStyle(rectangle.fillStyle);
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Rectangle (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Rectangle";

    }

    public int getLength() {
        return length;
    }

    public void setLength(int length) {
        this.length = length;
    }

    public int getWidth() {
        return width;

    }

    public void setWidth(int width) {
        this.width = width;

    }

    public FillStyle getFillStyle() {
        return fillStyle;
    }

    public void setFillStyle(FillStyle fillStyle) {
        this.fillStyle = fillStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("length=").append(length).append(", width=").append(width).append(", ").append(fillStyle);
        return builder.toString();
    }

}

Here's the code for Triangle class:

package org.trishinfotech.prototype.example1;

public class Triangle extends Shape {

    protected int sideA;
    protected int sideB;
    protected int sideC;
    protected FillStyle fillStyle;

    public Triangle() {
        super();
    }

    // prototype or deep copy constructor
    public Triangle(Triangle triangle) {
        super(triangle);
        System.out.println("Deep Copying Triangle...");
        this.sideA = triangle.sideA;

        this.sideB = triangle.sideB;
        this.sideC = triangle.sideC;
        this.fillStyle = new FillStyle(triangle.fillStyle);
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Triangle (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Triangle";
    }

    public int getSideA() {
        return sideA;
    }

    public void setSideA(int sideA) {
        this.sideA = sideA;
    }

    public int getSideB() {
        return sideB;
    }

    public void setSideB(int sideB) {
        this.sideB = sideB;

    }

    public int getSideC() {

        return sideC;

    }

    public void setSideC(int sideC) {
        this.sideC = sideC;
    }

    public FillStyle getFillStyle() {
        return fillStyle;
    }

    public void setFillStyle(FillStyle fillStyle) {
        this.fillStyle = fillStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("sideA=").append(sideA).append(", sideB=").append(sideB).append(", sideC=").append(sideC)
                .append(", ").append(fillStyle);
        return builder.toString();
    }

}

现在是时候编写Main 类来执行和测试输出了：

package org.trishinfotech.prototype.example1;

import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.FillPattern;
import org.trishinfotech.prototype.LinePattern;

public class Main {

    public static void main(String[] args) {

        Circle circle = new Circle();

        circle.setX(10);

        circle.setY(10);
        ShapeStyle circleStyle = new ShapeStyle();

        circleStyle.setLineColor(Color.BLUE);
        circleStyle.setLinePattern(LinePattern.DOT);
        circleStyle.setLineThickness(1.1d);
        FillStyle circleFillStyle = new FillStyle();
        circleFillStyle.setFillColor(Color.YELLOW);
        circleFillStyle.setFillPattern(FillPattern.HEART);
        circle.setStyle(circleStyle);
        circle.setFillStyle(circleFillStyle);

        System.out.println("Drawing original object");

        System.out.println("-------------------------------------------------------------------------");
        circle.draw();
        System.out.println("Making Deep Copy of original object");
        Circle deepCopyCircle = new Circle(circle);
        System.out.println("Drawing deep copy object");
        System.out.println("-------------------------------------------------------------------------");
        deepCopyCircle.draw();
       System.out.println("Modifying deep copy object");
        deepCopyCircle.setX(20);

        deepCopyCircle.getStyle().setLineColor(Color.RED);
        deepCopyCircle.getFillStyle().setFillPattern(FillPattern.CHECKS);
        System.out.println("\n\nDrawing original object");
        System.out.println("-------------------------------------------------------------------------");
        circle.draw();
        System.out.println("Drawing deep copy object");
        System.out.println("-------------------------------------------------------------------------");
        deepCopyCircle.draw();
    }

}

如您所见，创建原始对象需要执行许多语句。但是，我们只需要一个语句即可复制相同的实例。稍后，我们可以轻松更改所需的值。

以下是输出：

Drawing original object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Making Deep Copy of original object
Deep Copying Shape...
Deep Copying ShapeStyle...
Deep Copying Circle...
Deep Copying FillStyle...
Drawing deep copy object
-------------------------------------------------------------------------

Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).

Modifying deep copy object


Drawing original object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Drawing deep copy object
-------------------------------------------------------------------------
Drawing Circle (x=20, y=10, lineColor=RED, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=CHECKS).

使用原型设计模式的几何形状示例-克隆方法 现在，让我们使用Cloneable 接口做同样的例子。这是ShapeStyle 类的代码：

package org.trishinfotech.prototype.example2;

import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.LinePattern;

public class ShapeStyle implements Cloneable {
    protected Color lineColor;
    protected LinePattern linePattern;
    protected double lineThickness;

    public ShapeStyle() {
        super();
    }

    // implemented clone method
    @Override
    protected ShapeStyle clone 
        return (ShapeStyle) 
    }

    public Color getLineColor
        return lineColor
    }

    public void setLineColor(Color lineColor) {
        this.lineColor = lineColor;

    }

    public LinePattern getLinePattern() {
        return linePattern;
    }

    public void setLinePattern(LinePattern linePattern) {
        this.linePattern = linePattern;
    }

    public double getLineThickness() {
        return lineThickness;
    }

    public void setLineThickness(double lineThickness) {
        this.lineThickness = lineThickness;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("lineColor=").append(lineColor).append(", linePattern=").append(linePattern)
                .append(", lineThickness=").append(lineThickness);
        return builder.toString();
    }

}

这是FillStyle 类的代码：

package org.trishinfotech.prototype.example2;

import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.FillPattern;

public class FillStyle implements Cloneable {

    protected Color fillColor;

    protected FillPattern fillPattern;

    public FillStyle() {
        super();
    }

    // implemented clone method
    @Override
    public FillStyle clone() throws CloneNotSupportedException {
        return (FillStyle) super.clone();
    }

    public Color getFillColor() {
        return fillColor;
    }

    public void setFillColor(Color fillColor) {
        this.fillColor = fillColor;
    }

    public FillPattern getFillPattern() {
        return fillPattern;
    }

    public void setFillPattern(FillPattern fillPattern) {
        this.fillPattern = fillPattern;

    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("fillColor=").append(fillColor).append(", fillPattern=").append(fillPattern);
        return builder.toString();
    }

}

这是Shape 抽象类的代码：

package org.trishinfotech.prototype.example2;

public abstract class Shape implements Cloneable {
    protected int x;
    protected int y;
    protected ShapeStyle shapeStyle;
    public Shape() {
        super();
    }

    // implemented clone method
    @Override
    public Shape clone() throws CloneNotSupportedException {
        Shape shape = (Shape) super.clone();
        // call explicit clone for handling cloning of nested objects
        shape.shapeStyle = shapeStyle.clone();
        return shape;
    }

    abstract void draw();

    abstract String type();

    public int getX() {

        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public ShapeStyle getStyle() {
        return shapeStyle;
    }

    public void setStyle(ShapeStyle shapeStyle) {
        this.shapeStyle = shapeStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("x=").append(x).append(", y=").append(y).append(", ").append(shapeStyle);
        return builder.toString();
    }

}

这是Circle 类的代码：

package org.trishinfotech.prototype.example2;

public class Circle extends Shape {

    protected int radius;
    protected FillStyle fillStyle;

    public Circle() {
        super();
    }

    // implemented clone method
    @Override
    public Circle clone() throws CloneNotSupportedException {
        System.out.println("Cloning Circle...");
        Circle circle = (Circle) super.clone();
        // call explicit clone for handling cloning of nested objects
       circle.fillStyle = fillStyle.clone();
        return circle;
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Circle (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Circle";
    }

    public int getRadius() {
        return radius;
    }

    public void setRadius(int radius) {
        this.radius = radius;
    }

    public FillStyle getFillStyle() {
        return fillStyle;
    }

    public void setFillStyle(FillStyle fillStyle) {
        this.fillStyle = fillStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("radius=").append(radius).append(", ").append(fillStyle);
        return builder.toString();
    }

}

这是Line 类的代码：

package org.trishinfotech.prototype.example2;
public class Line extends Shape {
    protected int x1;
    protected int y1;

    public Line() {
        super();
    }

    // implemented clone method
    @Override
    public Line clone() throws CloneNotSupportedException {
        System.out.println("Cloning Rectangle...");
        return (Line) super.clone();

    }


    @Override
    public void draw() {
        System.out.printf("Drawing Line (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Line";
    }

    public int getX1() {
        return x1;
    }

    public void setX1(int x1) {
        this.x1 = x1;
    }

    public int getY1() {

        return y;
    }

    public void setY(int y1) {
        this.y1 = y1;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("x1=").append(x1).append(", y1=").append(y1);
        return builder.toString();
    }

}

这是Rectangle 类的代码：

package org.trishinfotech.prototype.example2;

public class Rectangle extends Shape {
    protected int length;
    protected int width;
    protected FillStyle fillStyle;

    public Rectangle() {
        super();
    }

    // implemented clone method
    @Override
    public Rectangle clone() throws CloneNotSupportedException {
        System.out.println("Cloning Rectangle...");
        Rectangle rectangle = (Rectangle) super.clone();
        // call explicit clone for handling cloning of nested objects
        rectangle.fillStyle = fillStyle.clone();
        return rectangle;
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Rectangle (%s, %s).\n", super.toString(), this.toString());
    }
    @Override
    String type() {
        return "Rectangle";

    }

    public int getLength() {
        return length;
    }

    public void setLength(int length) {
        this.length = length;
    }

    public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    public FillStyle getFillStyle() {
        return fillStyle;
    }

    public void setFillStyle(FillStyle fillStyle) {
        this.fillStyle = fillStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("length=").append(length).append(", width=").append(width).append(", ").append(fillStyle);
        return builder.toString();
    }

}

这是Triangle 类的代码：

package org.trishinfotech.prototype.example2;
public class Triangle extends Shape {
    protected int sideA;
    protected int sideB;
    protected int sideC;
    protected FillStyle fillStyle;
    public Triangle() {

        super();
    }

    // implemented clone method
    @Override
    public Triangle clone() throws CloneNotSupportedException {
        System.out.println("Cloning Triangle...");
        Triangle triangle = (Triangle) super.clone();
        // call explicit clone for handling cloning of nested objects
        triangle.fillStyle = fillStyle.clone();
     return triangle;
    }

    @Override
    public void draw() {
        System.out.printf("Drawing Triangle (%s, %s).\n", super.toString(), this.toString());
    }

    @Override
    String type() {
        return "Triangle";
    }
    public int getSideA() {
        return sideA;
    }

    public void setSideA(int sideA) {
        this.sideA = sideA;
    }
    public int getSideB() {
        return sideB;
    }
    public void setSideB(int sideB) {
        this.sideB = sideB;
    }

    public int getSideC() {
        return sideC;

    }

    public void setSideC(int sideC) {
        this.sideC = sideC;
    }

    public FillStyle getFillStyle() {
        return fillStyle;
    }

    public void setFillStyle(FillStyle fillStyle) {
        this.fillStyle = fillStyle;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder()
        builder.append("sideA=").append(sideA).append(", sideB=").append(sideB).append(", sideC=").append(sideC)
                .append(", ").append(fillStyle);
        return builder.toString();
    }

}

现在让我们编写Main 类来执行和测试输出：

package org.trishinfotech.prototype.example2;
import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.FillPattern;
import org.trishinfotech.prototype.LinePattern;
public class Main {
    public static void main(String[] args) throws CloneNotSupportedException {
        Circle circle = new Circle();
        circle.setX(10);
        circle.setY(10);
       ShapeStyle circleStyle = new ShapeStyle();
        circleStyle.setLineColor(Color.BLUE);
        circleStyle.setLinePattern(LinePattern.DOT);
       circleStyle.setLineThickness(1.1d);
        FillStyle circleFillStyle = new FillStyle();
        circleFillStyle.setFillColor(Color.YELLOW);
        circleFillStyle.setFillPattern(FillPattern.HEART);
        circle.setStyle(circleStyle);
        circle.setFillStyle(circleFillStyle);
        System.out.println("Drawing original object");
        System.out.println("-------------------------------------------------------------------------");
        circle.draw();
        System.out.println("Making clone of original object");
        Circle deepCopyCircle = circle.clone();
        System.out.println("Drawing clone object");
        System.out.println("-------------------------------------------------------------------------");
        deepCopyCircle.draw();
        System.out.println("Modifying clone object");
        deepCopyCircle.setX(20);
        deepCopyCircle.getStyle().setLineColor(Color.RED);
        deepCopyCircle.getFillStyle().setFillPattern(FillPattern.CHECKS);
        System.out.println("\n\nDrawing original object");
        System.out.println("-------------------------------------------------------------------------");
        circle.draw();
        System.out.println("Drawing clone object");
        System.out.println("-------------------------------------------------------------------------");
        deepCopyCircle.draw();
    }

}

借助clone（）方法几乎相同的代码。以下是输出：

Drawing original object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Making clone of original object
Cloning Circle...
Drawing clone object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Modifying clone object

Drawing original object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Drawing clone object
-------------------------------------------------------------------------
Drawing Circle (x=20, y=10, lineColor=RED, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=CHECKS).

使用原型设计模式的几何形状示例-克隆+原型注册表方法 让我们编写一个注册表类来保存我们拥有的所有形状对象。我们将使用地图来缓存形状对象原型。因此，我们将使用shape-type作为缓存的关键。我们可以采用不同的方式来实现此缓存注册表。因此，可以根据您的用例随意编写自己的代码。

以下是ShapeRegistry类的代码：

package org.trishinfotech.prototype.example2;
import java.util.HashMap;
import java.util.Map;
public class ShapeRagistry {

    protected static Map<String, Shape> CACHE = new HashMap<String, Shape>();
    public static Shape getByType(String type) {
        return CACHE.get(type);
    }

    public static void addShape(Shape shape) throws CloneNotSupportedException {
        CACHE.put(shape.type(), shape.clone());
    }
}

在这里我们可以看到我已经添加了获取和添加原型的方法。我们还可以使用静态块或构造函数来预定义原型对象池。

现在，我们将编写 Main 类来执行和测试输出：

package org.trishinfotech.prototype.example2;
import org.trishinfotech.prototype.Color;
import org.trishinfotech.prototype.FillPattern;
import org.trishinfotech.prototype.LinePattern;
public class ShapeRegistryMain {
    public static void main(String[] args) throws CloneNotSupportedException {
       Circle circle = new Circle();
        circle.setX(10);
        circle.setY(10);
        ShapeStyle circleStyle = new ShapeStyle();
        circleStyle.setLineColor(Color.BLUE);
        circleStyle.setLinePattern(LinePattern.DOT);
        circleStyle.setLineThickness(1.1d);
        FillStyle circleFillStyle = new FillStyle();
        circleFillStyle.setFillColor(Color.YELLOW);
        circleFillStyle.setFillPattern(FillPattern.HEART);
        circle.setStyle(circleStyle);
        circle.setFillStyle(circleFillStyle);

        System.out.println("Drawing original object");
        System.out.println("-------------------------------------------------------------------------");
       circle.draw();
        System.out.println("Making clone of original object");
        // check the registry if its already available at there.
        Circle deepCopyCircle = (Circle) ShapeRagistry.getByType(circle.type());
        if (deepCopyCircle == null) {
            // add it in the registry if its not available
            ShapeRagistry.addShape(circle);
        }
        // get the clone always from the regeistry and use.
        deepCopyCircle = (Circle) ShapeRagistry.getByType(circle.type());
        System.out.println("Drawing clone object");
        System.out.println("-------------------------------------------------------------------------");
        deepCopyCircle.draw();
        System.out.println("Modifying clone object");
        deepCopyCircle.setX(20);
        deepCopyCircle.getStyle().setLineColor(Color.RED);
        deepCopyCircle.getFillStyle().setFillPattern(FillPattern.CHECKS);
        System.out.println("\n\nDrawing original object");

        System.out.println("-------------------------------------------------------------------------");
        circle.draw();
        System.out.println("Drawing clone object");
        System.out.println("-------------------------------------------------------------------------");
        deepCopyCircle.draw();
    }

}

下面是程序的输出：

Drawing original object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Making clone of original object
Cloning Circle...
Drawing clone object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Modifying clone object

Drawing original object
-------------------------------------------------------------------------
Drawing Circle (x=10, y=10, lineColor=BLUE, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=HEART).
Drawing clone object
-------------------------------------------------------------------------
Drawing Circle (x=20, y=10, lineColor=RED, linePattern=DOT, lineThickness=1.1, radius=0, fillColor=YELLOW, fillPattern=CHECKS).

源代码可以在这里找到：原型设计模式样本代码

原文链接：http://codingdict.com

在Java中使用原型设计模式

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