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這篇文章主要介紹了Java中如何實(shí)現(xiàn)Prototype原型模式,具有一定借鑒價(jià)值,感興趣的朋友可以參考下,希望大家閱讀完這篇文章之后大有收獲,下面讓小編帶著大家一起了解一下。
一、場(chǎng)景描述
創(chuàng)建型模式中,從工廠方法模式,抽象工廠模式,到建造者模式,再到原型模式,我的理解是,創(chuàng)建對(duì)象的方式逐步從編碼實(shí)現(xiàn)轉(zhuǎn)向內(nèi)存對(duì)象處理。
例如,在“儀器數(shù)據(jù)采集器”的子類/對(duì)象“PDF文件數(shù)據(jù)采集器”和“Excel文件數(shù)據(jù)采集器”的創(chuàng)建過程中,
工廠模式下定義各子類,并由(抽象)工廠類Factory創(chuàng)建,因此各子類可在類定義中定義各自的屬性;
建造者模式下,通過不同的創(chuàng)建者類Builder創(chuàng)建不同的子對(duì)象,此時(shí)不再定義子類;
而原型模式下,則完全由調(diào)用者基于父對(duì)象克隆創(chuàng)建子對(duì)象,不在針對(duì)子對(duì)象創(chuàng)建類或者其相關(guān)的工廠、建造者類。
三種模式對(duì)應(yīng)于不同的場(chǎng)景,實(shí)際操作時(shí),根據(jù)場(chǎng)景合理選擇模式。
原型模式下,基于原型類對(duì)象,克隆創(chuàng)建新對(duì)象,因此為原型類對(duì)象賦予的屬性值在新對(duì)象中可直接使用,免去了重復(fù)賦值;
例如儀器數(shù)據(jù)采集器的共同初始化工作可在原型類對(duì)象中完成,隨后將其克隆出PDF文件數(shù)據(jù)采集器對(duì)象和Excel文件數(shù)據(jù)采集器對(duì)象,并為兩對(duì)象屬性做后續(xù)的擴(kuò)展,免去了公共屬性的初始化工作;
克隆操作在內(nèi)存中完成,由于對(duì)象類型的屬性值存儲(chǔ)為引用,因此克隆分淺克隆和深克隆,通過Serializable接口實(shí)現(xiàn)深克隆。
二、示例代碼
原型類:
package lims.designpatterndemo.prototypedemo; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; public class EquipmentDataCapture implements Cloneable, Serializable { private String filePath = "file path"; private String equipmentData = "file content"; // public String getFilePath() { return this.filePath; } public void setFilePath(String filePath) { this.filePath = filePath; } public String getEquipmentData() { return this.equipmentData; } public void setEquipmentData(String equipmentData) { this.equipmentData = equipmentData; } // private static final long serialVersionUID = 1L; private SerializableObject obj; // public SerializableObject getObj() { return obj; } public void setObj(SerializableObject obj) { this.obj = obj; } // public EquipmentDataCapture getEquipmentDataCapture() throws CloneNotSupportedException { EquipmentDataCapture capture = (EquipmentDataCapture) super.clone(); return capture; } // public EquipmentDataCapture getPdfFileCapture() throws CloneNotSupportedException { // EquipmentDataCapture capture = (EquipmentDataCapture) super.clone(); // capture.setEquipmentData("pdf file content"); // return capture; // } // public EquipmentDataCapture getExcelFileCapture() throws CloneNotSupportedException { // EquipmentDataCapture capture = (EquipmentDataCapture) super.clone(); // capture.setEquipmentData("excel file content"); // return capture; // } /* 深復(fù)制 */ public EquipmentDataCapture newEquipmentDataCapture() throws IOException, ClassNotFoundException { /* 寫入當(dāng)前對(duì)象的二進(jìn)制流 */ ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(this); /* 讀出二進(jìn)制流產(chǎn)生的新對(duì)象 */ ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray()); ObjectInputStream ois = new ObjectInputStream(bis); return (EquipmentDataCapture)ois.readObject(); } } class SerializableObject implements Serializable { private static final long serialVersionUID = 1L; }
調(diào)用端:
package lims.designpatterndemo.prototypedemo; public class PrototypeDemo { public static void main(String[] args) throws CloneNotSupportedException { EquipmentDataCapture edc = new EquipmentDataCapture(); EquipmentDataCapture capture = null; // capture = edc.getPdfFileCapture(); // capture = edc.getExcelFileCapture(); capture = edc.getEquipmentDataCapture(); capture.setEquipmentData("equipment data file content"); String fileContent = capture.getEquipmentData(); System.out.println(fileContent); } }
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