简单工厂

2019-11-06 07:51:38

字体：大中小

来源：转载

供稿：网友

参考《设计模式的艺术软件开发人员内功修炼之道》-刘伟著

实验目的

工厂方法是一种常见的制造对象的方法（其他，如new新对象，反射，clone等），其中简单工厂通过一个工厂类，根据入参生产出对应的子对象。

实验代码

import java.io.IOException;import java.util.HashMap;import java.util.Map;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import org.w3c.dom.Document;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import org.xml.sax.SAXException;/****************** SimpleFactory ********************/abstract class Chart { public void display() { }}class HistgramChart extends Chart { public HistgramChart() { } public void display() { System.out.PRintln("display HistgramChart ..."); }}class LinerChart extends Chart { public LinerChart() { } public void display() { System.out.println("display LinerChart ..."); }}class PieChart extends Chart { public PieChart() { } public void display() { System.out.println("display PieChart ..."); }}class SimpleFactory { public static Chart getChart(String type) { Chart chart = null; switch (type) { case "Histgram": chart = new HistgramChart(); break; case "Liner": chart = new LinerChart(); break; case "Pie": chart = new PieChart(); break; default: chart = new HistgramChart(); } return chart; }}/***************** Improved SimpleFactory *********************/class XMLUtil { private static DocumentBuilderFactory dFactory; private static DocumentBuilder dBuilder; private static Document doc; private static void init() { dFactory = DocumentBuilderFactory.newInstance(); try { dBuilder = dFactory.newDocumentBuilder(); doc = dBuilder.parse(new File("config.xml")); } catch (ParserConfigurationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SAXException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static String getChartType() { init(); NodeList nl = doc.getElementsByTagName("chartType"); Node node = nl.item(0).getFirstChild(); String chartType = node.getNodeValue().trim(); return chartType; } public static void getChartConfig() { init(); NodeList nl = doc.getElementsByTagName("chartInit"); NodeList nl_1 = nl.item(0).getChildNodes(); for (int index = 0; index < nl_1.getLength(); index++){ Node node = nl_1.item(index); if(node.getNodeName().equalsIgnoreCase("chartunit")){ String chartClass = null ,chartString = null; NodeList innerNL = node.getChildNodes(); for(int innerIndex = 0; innerIndex < innerNL.getLength(); innerIndex++){ Node innerNode = innerNL.item(innerIndex); if(innerNode.getNodeName().equalsIgnoreCase("chartClass")){ chartClass = innerNode.getFirstChild().getNodeValue(); } if(innerNode.getNodeName().equalsIgnoreCase("chartString")){ chartString = innerNode.getFirstChild().getNodeValue(); } if(chartClass != null && chartString != null) ImprovedSimpleFactory.putChart(chartClass, chartString); } } } }}class ImprovedSimpleFactory { private static Map<String,String> chartMap = new HashMap<String,String>(); public static Chart getChart(String type) { /* System.out.println("chartMap's size is " + chartMap.size()); for(Map.Entry<String, String> entry : chartMap.entrySet()){ System.out.println("key is " + entry.getKey() + " : value is " + entry.getValue()); }*/ String chartClass = chartMap.get(type); // System.out.println("type is " + type); if(chartClass != null){ try { Chart chart = (Chart)Class.forName(chartClass).newInstance(); return chart; } catch (InstantiationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Illegal accessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return null; } public static void putChart(String chartClass, String chartType){ chartMap.put(chartType,chartClass); }}public class SimpleFactoryTest { public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("================SimpleFactory==================="); Chart histgramChart = SimpleFactory.getChart("Histgram"); histgramChart.display(); Chart linerChart = SimpleFactory.getChart("Liner"); linerChart.display(); Chart pieChart = SimpleFactory.getChart("Pie"); pieChart.display(); System.out.println("================ImprovedSimpleFactory==================="); String chartType = XMLUtil.getChartType(); XMLUtil.getChartConfig(); Chart chart = SimpleFactory.getChart(chartType); chart.display(); Chart improvedChart = ImprovedSimpleFactory.getChart(chartType); improvedChart.display(); }}

结果输出

================SimpleFactory===================display HistgramChart ...display LinerChart ...display PieChart ...================ImprovedSimpleFactory===================display LinerChart ...display LinerChart ...