模拟Spring的读取xml资料及注入
模拟Spring的读取xml文件及注入
简单的xml配置文件
BeanFactory接口
实现BeanFactory的接口
调用测试:
简单的xml配置文件
<?xml version="1.0" encoding="UTF-8"?> <beans> <bean id="userDAO" class="com.king.dao.impl.UserDAOImpl"></bean> <bean id="userService" class="com.king.service.impl.UserServiceImpl"> <property name="userDAO" ref="userDAO"></property> </bean> </beans>
BeanFactory接口
public interface BeanFactory { public Object getBean(String name); }
实现BeanFactory的接口
public class ClassPathXmlApplicationContext implements BeanFactory{ private Map<String,Object> beans = new HashMap<String,Object>(); // map for store beans /***constructor****/ public ClassPathXmlApplicationContext() { SAXBuilder sb = new SAXBuider(); Document doc = sb.builder(this.getClass().getClassLoader().getResourceAsStream("beans.xml"));//read the xml file in classpath Element root = doc.getRootElement(); // beans List list = root.getChildren("bean"); // all beans in that list int size = list.size(); for(int i = 0; i< size; i++) { Element element = list.get(i); String id = element.getAttributeValue("id"); // get id String clazz = element.getAttributeValue("class"); // get class Object o = Class.forName(clazz).newInstance(); // reflect beans.put(id,o); // put into the map List<Element> properties = (List<Element>) element.getChildren("property"); // get property config,for DI for(Element property : properties) { String name = property.getAttributeValue("name"); // get name String ref = property.getAttributeValue("ref"); // get reference bean name Object refBean = beans.get(ref); // get reference bean form map String methodName = "set" + name.subString(0,1).toUpperCase() + name.subString(1); // setter method name System.out.println(methodName); Method m = o.getClass().getMethod(methodName,refBean.getClass.getInterfaces()[0]); // get method parameters m.invoke(o,refBean); // execute to inject reference bean } } } public Object getBean(String name) { return beans.get(name); }
调用测试:
public SpringTest{ @Test public void testAdd() { BeanFactory factory = new ClassPathXmlApplicationContext(); UserService service = (UserService) factory.getBean("userService"); User u = new User(); service.add(u); } }