spring 底層實現IOC DI簡單依賴反射
1.準備實體，dao介面和實現類，service介面和實現類,spring.xml配置檔案
實體：public class User implements Serializable{
private Integer id;
private String name;
private Integer age;
public User(Integer id, String name, Integer age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public User() {
super();
// TODO Auto-generated constructor stub
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
dao介面和實現類
public interface UserDao {
List<User> queryAll();
}
public class UserDaoImpl implements UserDao {
@Override
public List<User> queryAll() {
// TODO Auto-generated method stub
System.out.println("++++++query all users++++");
return null;
}
}
service介面和實現類
public interface UserService {
List<User> selectAll();
}
public class UserServiceImpl implements UserService {
private UserDao userDao;
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
@Override
public List<User> selectAll() {
// TODO Auto-generated method stub
return userDao.queryAll();
}
}
spring.xml檔案
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd ">
<bean id="userDao" class="org.hi.software.test.dao.UserDaoImpl"/>
<bean id="userService" class="org.hi.software.test.service.UserServiceImpl">
<property name="userDao" ref="userDao"/>
</bean>
</beans>
2.
a、讀取xml檔案
//存放所有的bean節點
HashMap<String, String> beanMap = new HashMap<String, String>();
//存放所有bean節點對應的property集合{'beanid1':'{'name':'ref','name','value'}','beanid2':'{'',''}'}
HashMap<String, Map<String, String>> propertyMap = new HashMap<String, Map<String, String>>();
//工廠存放beanid ，和對應的物件
HashMap<String, Object> context = new HashMap<String, Object>();
b、
拿到bean節點，遍歷所有的property屬性拿到property屬性的集合propertyAttributeMap（<name,ref>或者<name,value>） 把propertyAttributeMap作為value，beanId作為key，放入集合propertyMap //遍歷拿到節點的key value for (int i = 0; i < elementsByTagName.getLength(); i++) { Element beanitem = (Element) elementsByTagName.item(i); String beanid = beanitem.getAttribute("id"); String beanclass = beanitem.getAttribute("class"); //System.out.println(beanclass+"---->"+beanid); beanMap.put(beanid, beanclass); //獲取每個bean下的property屬性 NodeList elementsByTagName2 = beanitem.getElementsByTagName("property"); Map<String, String> propertyAttributeMap=new HashMap<String, String>(); for (int j = 0; j < elementsByTagName2.getLength(); j++) { Element propertyitem = (Element)elementsByTagName2.item(j); String name = propertyitem.getAttribute("name"); String ref = propertyitem.getAttribute("ref"); //System.out.println(name+"---"+ref); propertyAttributeMap.put(name, ref); } propertyMap.put(beanid,propertyAttributeMap); } d、IOC：beanMap轉化為context工廠（beanID-->物件） for (Map.Entry<String, String> bean : beanMap.entrySet()) { String beanid = bean.getKey(); String beanclass = bean.getValue(); Object object = Class.forName(beanclass).newInstance(); context.put(beanid, object); } e、DI:遍歷propertyMap，通過key找到bean物件，value就是property集合包含name和value（ref） 組裝setName方法進行賦值，如果不是基本型別，應通過context獲得複雜物件進行賦值 for (Map.Entry<String, Map<String, String>> beanProperty:propertyMap.entrySet()) { String bid = beanProperty.getKey(); Object target = context.get(bid); System.out.println("target:"+target); Map<String, String> value = beanProperty.getValue(); for (Map.Entry<String, String> proString :value.entrySet()) { String name = proString.getKey(); String ref = proString.getValue(); Object object = context.get(ref); System.out.println("object:"+object); String methodName="set"+name.substring(0, 1).toUpperCase()+name.substring(1); Method declaredMethod = target.getClass().getDeclaredMethod(methodName,context.get(ref).getClass().getInterfaces()[0]); declaredMethod.invoke(target, object); } 3.測試 UserService us = (UserService) context.get("userService");us.selectAll();