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Android设计模式--原型模式

时间:2024-3-2 18:56     作者:韩俊     分类: Android


1、定义:

用原型实例指定创建对象种类,并通过拷贝这些原型创建新的对象。

2、目的:

从一个对象创建另外一个可定制的对象,而不需要知道任何创建细节。

3、作用:

3.1、简化对象的创建;

3.2 、对于处理大对象,性能上比new 高出很多。

4、分类:

4.1浅拷贝:拷贝对象中的基本的数据类型,对于数组、容器对象、引用对象等都不会拷贝。

4.2深拷贝:将所有类型进行拷贝。

5、注意:

5.1对象实现Cloneable接口,必须将Object clone() 方法改为public;

5.2对于基本数据类型,其封装类型,String不需要进行处理。他们进行的均是深拷贝。


6、简单的demo:

浅拷贝:

package com.example.demo.Prototype;
/**
 *  浅拷贝
 * @author qubian
 * @data 2015年6月4日
 * @email naibbian@163.com
 *
 */
public class Prototype implements Cloneable {

    private int num;
    private String name;

    public int getNum() {
        return num;
    }
    public void setNum(int num) {
        this.num = num;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public Object clone() {
        Prototype prototype = null;
        try {
            prototype = (Prototype) super.clone();

        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return prototype;
    }

}

深拷贝:
package com.example.demo.Prototype;

import java.util.ArrayList;
import java.util.Vector;
/**
 * 深拷贝
 * @author qubian
 * @data 2015年6月4日
 * @email naibbian@163.com
 *
 */
public class DeepPrototype implements Cloneable{

    private String name;
    private ArrayList<String> arrayList;

    private DeepObject deepObject;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public ArrayList<String> getArrayList() {
        return arrayList;
    }
    public void setArrayList(ArrayList<String> arrayList) {
        this.arrayList = arrayList;
    }
    public DeepObject getDeepObject() {
        return deepObject;
    }
    public void setDeepObject(DeepObject deepObject) {
        this.deepObject = deepObject;
    }
    /**
     * clone 方法
     */
    @SuppressWarnings("unchecked")
    @Override
    public Object clone() {
        DeepPrototype prototype = null;
        try {
            prototype = (DeepPrototype) super.clone();
            prototype.arrayList=(ArrayList<String>) this.arrayList.clone();
            prototype.deepObject=(DeepObject) this.deepObject.clone();

        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return prototype;
    }

    class DeepObject implements Cloneable
    {
        String name;
        protected Object clone()  {
            DeepObject deep=null;
            try {
                deep= (DeepObject) super.clone();
            } catch (CloneNotSupportedException e) {
                e.printStackTrace();
            }
            return deep;
        };
    }
}

7、原型模式在Android中的运用:

最明显的例子就是Intent,但是好像还未知其用处。

但是细看,居然还是new 的对象。

public class Intent implements Parcelable, Cloneable {
    /**
     * Copy constructor.
     */
    public Intent(Intent o) {
        this.mAction = o.mAction;
        this.mData = o.mData;
        this.mType = o.mType;
        this.mPackage = o.mPackage;
        this.mComponent = o.mComponent;
        this.mFlags = o.mFlags;
        if (o.mCategories != null) {
            this.mCategories = new ArraySet<String>(o.mCategories);
        }
        if (o.mExtras != null) {
            this.mExtras = new Bundle(o.mExtras);
        }
        if (o.mSourceBounds != null) {
            this.mSourceBounds = new Rect(o.mSourceBounds);
        }
        if (o.mSelector != null) {
            this.mSelector = new Intent(o.mSelector);
        }
        if (o.mClipData != null) {
            this.mClipData = new ClipData(o.mClipData);
        }
    }

    @Override
    public Object clone() {
        return new Intent(this);
    }

}


标签: android

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