java工厂模式——Spring示例

package com.fsti.factory.factorybean;

public interface Output {
	public final static Integer MAX_CACHE_LINE = 3;

	void getData(String str);

	void out();
}

package com.fsti.factory.factorybean;

public class Printer implements Output {
	private String[] printData = new String[MAX_CACHE_LINE];
	// 用以记录当前需打印的作业数
	private int dataNum = 0;

	public void getData(String str) {
		if (dataNum >= MAX_CACHE_LINE) {
			System.out.println("输出队列一满，添加失败");
		} else {
			printData[dataNum++] = str;
		}
	}

	public void out() {
		while (dataNum > 0) {
			System.out.println("打印机打印：" + printData[0]);
			// 把作业整体前移一位，并将剩下的作业数减一
			System.arraycopy(printData, 1, printData, 0, --dataNum);
		}
	}
}

package com.fsti.factory.factorybean;

public class BetterPrinter implements Output {
	private String[] printData = new String[MAX_CACHE_LINE];
	// 用以记录当前需打印的作业数
	private int dataNum = 0;

	public void getData(String str) {
		if (dataNum >= MAX_CACHE_LINE) {
			System.out.println("输出队列一满，添加失败");
		} else {
			printData[dataNum++] = str;
		}
	}

	public void out() {
		while (dataNum > 0) {
			System.out.println("Better打印机打印：" + printData[0]);
			// 把作业整体前移一位，并将剩下的作业数减一
			System.arraycopy(printData, 1, printData, 0, --dataNum);
		}
	}
}

package com.fsti.factory.factorybean;

public interface ApplicationContext {
	Object getBean(String name) throws Exception;
}

package com.fsti.factory.factorybean;

import java.io.File;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class SJxmlApplicationContext implements ApplicationContext {

	// 保存容器中所有单利模式的Bean对象
	private Map<String, Object> objPool = Collections.synchronizedMap(new HashMap<String, Object>());
	// 保存对应文件中的Document对象
	private Document doc;
	// 保存配置文件中的根元素
	private Element root;

	public SJxmlApplicationContext(String filePath) throws Exception {
		SAXReader reader = new SAXReader();
		doc = reader.read(new File(filePath));
		root = doc.getRootElement();
		initPool();
		initProp();
	}

	public Object getBean(String name) throws Exception {
		Object target = objPool.get(name);
		// 对于singleton Bean，容器已经初始化了所有Bean实例
		if (target.getClass() != String.class) {
			return target;
		} else {
			String clazz = (String) target;
			// 对于prototype并未注入属性值
			return Class.forName(clazz).newInstance();
		}
	}

	// 初始化容器中的所有singleton Bean
	private void initPool() throws Exception {
		// 遍历配置文件里每个<bean.../>元素
		for (Object obj : root.elements()) {
			Element beanEle = (Element) obj;
			// 取得元素的id属性
			String beanId = beanEle.attributeValue("id");
			// 取得元素的class属性
			String beanClazz = beanEle.attributeValue("class");
			// 取得元素的scope属性
			String beanScope = beanEle.attributeValue("scope");
			// 如果scope属性不存在，或为singleton
			if (beanScope == null || beanScope.equals("singleton")) {
				// 从默认的构造器创建Bean实例，并将其放入objPool中
				objPool.put(beanId, Class.forName(beanClazz).newInstance());
			} else {
				// 对于非singleton Bean，存放该Bean实现类的类名
				objPool.put(beanId, beanClazz);
			}
		}

	}

	private void initProp() throws Exception {
		for (Object obj : root.elements()) {
			Element beanEle = (Element) obj;
			// 取得元素的id属性
			String beanId = beanEle.attributeValue("id");
			// 取得元素的scope属性
			String beanScope = beanEle.attributeValue("scope");
			if (beanScope == null || beanScope.equals("singleton")) {
				// 取出objPool指定的bean实例
				Object bean = objPool.get(beanId);
				// 遍历元素的每个<property.../>元素
				for (Object prop : beanEle.elements()) {
					Element propEle = (Element) prop;
					// 取得name属性的值
					String propName = propEle.attributeValue("name");
					// 取得value属性的值
					String propValue = propEle.attributeValue("value");
					// 取得元素的ref属性
					String propRef = propEle.attributeValue("ref");
					// 将属性的首字母大写
					String propNameCamelize = propName.substring(0, 1).toUpperCase() + propName.substring(1, propName.length());
					// 如果<property.../>元素的value属性值存在
					if (propValue != null && propValue.length() > 0) {
						Method setter = bean.getClass().getMethod("set" + propNameCamelize, String.class);
						// 执行setter注入
						setter.invoke(bean, propValue);
					}
					if (propRef != null && propRef.length() > 0) {
						// 取得需要被依赖注入的Bean实例
						Object target = objPool.get(propRef);
						// objPool池中不存在指定Bean实例
						if (target == null) {
							// 此处还应处理singleton Bean依赖prototype Bean的情形
						}
						// 定义设置注入所需的setter方法
						Method setter = null;
						// 遍历target对象所实现的所有接口
						for (Class superInterface : target.getClass().getInterfaces()) {
							setter = bean.getClass().getMethod("set" + propNameCamelize, superInterface);
							// 如果成功取得该接口对应的方法，直接跳出循环
							break;
						}
						// 如果setter方法依然是null
						// 则直接取得target实现对应的setter方法
						if (setter == null) {
							setter = bean.getClass().getMethod("set" + propNameCamelize, target.getClass());
						}
						// 执行setter注入
						setter.invoke(bean, target);
					}
				}
			}
		}
	}
}

package com.fsti.factory.factorybean;

public class Computer {

	private Output out;
	private String name;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Output getOut() {
		return out;
	}

	public void setOut(Output out) {
		this.out = out;
	}

	public Computer() {
	}

	public Computer(Output out) {
		this.out = out;
	}

	public void keyIn(String str) {
		out.getData(str);
	}

	public void print() {
		out.out();
	}
}

package com.fsti.factory.factorybean;

public class IocTest {

	public static void main(String[] args) throws Exception {
		ApplicationContext ctx = new SJxmlApplicationContext("bean.xml");
		Computer c = (Computer) ctx.getBean("computer");

		c.keyIn("工厂模式之");
		c.keyIn("简单工厂模式(spring方式)");
		c.print();
		System.out.println(c.getName());
		System.out.println(ctx.getBean("now"));
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans>
	<bean id="computer" class="com.fsti.factory.factorybean.Computer">
		<property name="name" value="工厂的Bean方式"/>
		<property name="out" ref="printer"/>
	</bean>
	<bean id="printer" class="com.fsti.factory.factorybean.Printer"></bean>
	<bean id="betterPrinter" class="com.fsti.factory.factorybean.BetterPrinter"></bean>
	<bean id="now" class="java.util.Date" scope="prototype"></bean>
</beans>