Spring学习 6

1.bean 与 bean之间的关系是Spring的web.xml来维护的。

<bean id="userService" class="com.spring.study.service.impl.UserServiceImpl">
<property name="userDao" ref="userDao" />
<!-- 
<property name="userDaoAA" ref="userDao" />
  public void setUserDaoAA(UserDao userDao) {this.userDao = userDao;} -->
</bean>

<bean id="userDao" class="com.spring.study.dao.impl.UserDaoImpl" />

2.自己实现的Spring bean 与bean之间的关系注入

public class CnpcClassPathXmlApplicationContext {private List<BeanDefinition> beanDefines = new ArrayList<>();//[com.spring.framework.BeanDefinition@589af639, com.spring.framework.BeanDefinition@259b45a1]private Map<String, Object> singletons = new HashMap<>();//{userService=com.spring.study.service.impl.UserServiceImpl@6eb1054b, userDao=com.spring.study.dao.impl.UserDaoImpl@27d2b7b3}// beanId -- beanClass对象public CnpcClassPathXmlApplicationContext(String fileName) {this.readXML(fileName);this.instanceBeans();this.injectObject();}/** * 注入property属性，构造bean与bean的关联关系 */private void injectObject() {for (BeanDefinition beanDefinition : beanDefines) { // 循环所有的beanObject bean = singletons.get(beanDefinition.getId());//com.spring.study.service.impl.UserServiceImpl@47ca5c4f// 取得实例化后的bean对象if (bean != null) {try {<strong>PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors()</strong>;for (PropertyDefinition propertyDefinition : beanDefinition//java.beans.PropertyDescriptor[name=class; propertyType=class java.lang.Class; readMethod=public final native java.lang.Class java.lang.Object.getClass()]//java.beans.PropertyDescriptor[name=userDao; propertyType=interface com.spring.study.dao.UserDao; readMethod=public com.spring.study.dao.UserDao com.spring.study.service.impl.UserServiceImpl.getUserDao(); writeMethod=public void com.spring.study.service.impl.UserServiceImpl.setUserDao(com.spring.study.dao.UserDao)].getPropertys()) { //获取bean下面的propertyfor (PropertyDescriptor properdesc : ps) {System.out.println(properdesc.getName());//class//userDaoif (propertyDefinition.getName().equals(properdesc.getName())) {//com.spring.framework.PropertyDefinition@71f80d51 name ref userDao//java.beans.PropertyDescriptor[name=userDao; propertyType=interface com.spring.study.dao.UserDao; readMethod=public com.spring.study.dao.UserDao com.spring.study.service.impl.UserServiceImpl.getUserDao(); writeMethod=public void com.spring.study.service.impl.UserServiceImpl.setUserDao(com.spring.study.dao.UserDao)]<strong>Method setter = properdesc.getWriteMethod();</strong> // 获取属性的setter方法if (setter != null) {Object value = singletons.get(propertyDefinition.getRef());setter.setAccessible(true); // private<strong>setter.invoke(bean, value);</strong> // 把引用对象注入到属性}break;}}}} catch (Exception e) {e.printStackTrace();}}}}/** * 完成bean的实例化 */private void instanceBeans() {for (BeanDefinition beanDefine : beanDefines) {if (beanDefine != null && !"".equals(beanDefine.getClassName()))try {singletons.put(beanDefine.getId(),Class.forName(beanDefine.getClassName()).newInstance());} catch (Exception e) {e.printStackTrace();}}}/** * 读取xml配置文件 *  * @param fileName */@SuppressWarnings("unchecked")private void readXML(String fileName) {SAXReader saxReader = new SAXReader();Document document = null;try {URL xmlpath = this.getClass().getClassLoader().getResource(fileName);document = saxReader.read(xmlpath);Map<String, String> nsMap = new HashMap<>();nsMap.put("ns", "http://www.springframework.org/schema/beans");// 加入命名空间XPath xsub = document.createXPath("//ns:beans/ns:bean");// 创建beans/bean查询路径xsub.setNamespaceURIs(nsMap);// 设置命名空间List<Element> beans = xsub.selectNodes(document);// 读取文档下所有bean节点for (Element element : beans) {String id = element.attributeValue("id");// 获取id属性值String clazz = element.attributeValue("class");// 获取class属性值BeanDefinition beanDefintion = new BeanDefinition(id, clazz);XPath propertysub = document.createXPath("ns:property");propertysub.setNamespaceURIs(nsMap);List<Element> propertys = propertysub.selectNodes(element);for (Element propertyElement : propertys) {String name = propertyElement.attributeValue("name");String ref = propertyElement.attributeValue("ref");// System.out.println(name + "--" + ref);PropertyDefinition propertyDefintion = new PropertyDefinition(name, ref);beanDefintion.getPropertys().add(propertyDefintion);}beanDefines.add(beanDefintion);}} catch (Exception e) {e.printStackTrace();}}public Object getBean(String beanName) {return singletons.get(beanName);}}

public class PropertyDefinition {private String name;private String ref;public PropertyDefinition() {}public PropertyDefinition(String name, String ref) {this.name = name;this.ref = ref;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getRef() {return ref;}public void setRef(String ref) {this.ref = ref;}}

public class BeanDefinition {private String id;private String className;private List<PropertyDefinition> propertys = new ArrayList<>();public BeanDefinition() {}public BeanDefinition(String id, String className) {this.id = id;this.className = className;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getClassName() {return className;}public void setClassName(String className) {this.className = className;}public List<PropertyDefinition> getPropertys() {return propertys;}public void setPropertys(List<PropertyDefinition> propertys) {this.propertys = propertys;}}