通过构造器注入IOC的依赖关系

IOC的依赖注入方式有： 

³构造器注入:通过类的构造方法注入依赖关系 
设值方法注入:通过类的setters方法注入依赖关系 
 接口注入（不常用）:定义一个注入接口，在需要注入的类中实现此接口，由于这种方法具有侵入性，所以不常用
一、构造器注入
    (1)使用到的接口

接口UserDao.java

package com.zhmg.spring.dao;   public interface UserDao {       public void save(String username,String password);     }

 

接口UserManager.java

package com.zhmg.spring.manager;   import com.zhmg.spring.dao.UserDao;   public interface UserManager {       public void save(String username, String password);   }

(2)接口的不同实现

 

UserDao4MySqlImpl.java----对接口UserDao的实现

package com.zhmg.spring.dao;   public class UserDao4MySqlImpl implements UserDao {       public void save(String username, String password) {       System.out.println("使用MySql时对UserDao的实现");     } }

 
 

UserDao4OracleImpl.java----对接口UserDao的实现

package com.zhmg.spring.dao;   public class UserDao4MySqlImpl implements UserDao {       public void save(String username, String password) {       System.out.println("使用Oracle时对UserDao的实现");     } }

UserManagerImpl.java----对UserManager接口的实现

package com.zhmg.spring.manager;   import com.zhmg.spring.dao.UserDao;   public class UserManagerImpl implements UserManager {       public UserDao userDao = null;       public void save(String username, String password) {        this.userDao.save(username, password);     }         public void setUserDao(UserDao userDao) {        this.userDao = userDao;     }   }

(3)applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"          xmlns:aop="http://www.springframework.org/schema/aop"          xmlns:tx="http://www.springframework.org/schema/tx"          xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">     <bean id="userDao4MySql"   class="com.zhmg.spring.dao.UserDao4MySqlImpl"/>   <bean id="userDao4Oracle" class="com.zhmg.spring.dao.UserDao4OracleImpl"/>   <bean id="userManager" class="com.zhmg.spring.manager.UserManagerImpl">        <constructor-arg ref="userDao4MySql"/>      </bean> </beans>

(4)测试结果

package com.zhmg.spring.client;   import org.springframework.beans.factory.BeanFactory; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.zhmg.spring.dao.UserDao4OracleImpl; import com.zhmg.spring.manager.UserManagerImpl;   public class Client {        public static void main(String []agrs){ BeanFactory factory = new ClassPathXmlApplicationContext("applicationContext.xml"); UserManager userManager = (UserManager)factory.getBean("userManager");                  userManager.save("测试", "123");        } }

使用MySql时对UserDao的实现

 

(5)总结

   使用Spring时并不需要继承Spring的任何类或者接口(轻量级的一种体现),使得程序的层次更加分明,程序的耦合度降低,侵入性降低,因此程序便于维护,复用率更高。即使当初使用了Sping进行的设计,以后需要用其他技术代替Spring对程序的影响不是很大

 

                                                                                                 ----------此实例的设计思想以及大部分代码来自北京尚学堂