模拟ioc

用这样一个简单的场景模拟spring的Ioc：





先建立car类：
package com.deciphering.car;
public interface Car {
public String getBrand();
public void run();
}

package com.deciphering.carImplementation;
import com.deciphering.car.Car;
public class BMWCar implements Car {
private final String MyBrand = "宝马";
@Override
public String getBrand() {
return MyBrand;
}
@Override
public void run() {
System.out.println(MyBrand + " is runnning!");
}
}

再建立human类
package com.deciphering.human;
import com.deciphering.car.Car;
public class Human {
private Car car;
public Car getCar() {
return car;
}
public void setCar(Car car) {
this.car = car;
}
public void myCarRun() {
car.run();
}
}

很简单，就是2个javabean；

接下来模拟bean工厂
package com.deciphering.spring;
public interface BeanFactoryTest {
public Object getBean(String id);
}

package com.deciphering.spring;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
public class ClassPathXmlApplicationContextTest implements BeanFactoryTest {
private final Map<String, Object> beans = new HashMap<String, Object>();
public ClassPathXmlApplicationContextTest() throws Exception {
final SAXBuilder sb = new SAXBuilder();
System.out.println("开始读取配置文件");
final Document doc = sb.build(this.getClass().getClassLoader().getResourceAsStream("beans.xml"));
final Element root = doc.getRootElement();
final List list = root.getChildren("bean");
for (int i = 0; i < list.size(); i++) {
final Element element = (Element) list.get(i);
final String id = element.getAttributeValue("id");
final String clazz = element.getAttributeValue("class");
final Object o = Class.forName(clazz).newInstance();
System.out.println("bean id: " + id);
System.out.println("bean class: " + clazz);
beans.put(id, o);
for (final Element propertyElement : (List<Element>) element.getChildren("property")) {
final String name = propertyElement.getAttributeValue("name");
final String bean = propertyElement.getAttributeValue("bean");
System.out.println("property name: " + name);
System.out.println("property bean: " + bean);
final Object beanObject = beans.get(bean);
final String methodName = "set" + name.substring(0, 1).toUpperCase() + name.substring(1);
System.out.println("根据property name构造method name = " + methodName);
System.out.println("开始利用反射执行setter注入... ");
final Method m = o.getClass().getMethod(methodName, beanObject.getClass().getInterfaces()[0]);
m.invoke(o, beanObject);
}
}
}
@Override
public Object getBean(String id) {
return beans.get(id);
}
}

然后建立一个配置文件beans.xml
<beans>
<bean id="car" class="com.deciphering.carImplementation.BMWCar" >
</bean>

<bean id="human" class="com.deciphering.human.Human" >
<property name = "car" bean = "car"></property>
</bean>

</beans>

接下来就写一个测试类：
package com.deciphering.humen;
import org.junit.Test;
import com.deciphering.human.Human;
import com.deciphering.spring.ClassPathXmlApplicationContextTest;
public class HumenTest {
@Test
public void testHumen() throws Exception {
final ClassPathXmlApplicationContextTest ctx = new ClassPathXmlApplicationContextTest();
final Human human = (Human) ctx.getBean("human");
// Car car = (BMWCar)ctx.getBean("car");
// human.setCar(car);
System.out.println("setter注入完成，开始执行测试 ");
human.myCarRun();
}
}

输出：

开始读取配置文件
bean id: car
bean class: com.deciphering.carImplementation.BMWCar
bean id: human
bean class: com.deciphering.human.Human
property name: car
property bean: car
根据property name构造method name = setCar
开始利用反射执行setter注入...
setter注入完成，开始执行测试
宝马 is runnning!

一个简单的Spring的Ioc就完成了