04 Spring IoC

1、IoC的概念

IoC，控制反转，就是将对象的实例化交给Spring容器，通过Spring容器的实例化来降低层与层之间以及程序之间的耦合与依赖。

2、IoC容器对象

BeanFactory

ApplicationContext

通过ClassPathXmlApplicationContext创建容器对象ApplicationContext

ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

通过容器对象获取注入的对象

UserDao userDao = (UserDao)context.getBean("userDao");

3、DI的方式

3.1 基于属性的注入

User代码

public class User {
	private String name;
	private String mobile;
	
	//构造函数 - 构造函数注入
	public User(String name,String mobile)
	{
		this.name = name;
		this.mobile = mobile;
	}
	
	public String toString()
	{
		return "用户名:"+this.name+";手机号:"+this.mobile;
	}
}

UserDao代码

public interface UserDao {
	public void insert(User user); 	//添加用户
}

接口实现1：

public class UserDaoImpl1 implements UserDao {

	@Override
	public void insert(User user) {
		System.out.println("用户["+user+"]被新增1");
	}
}

接口实现2：

public class UserDaoImpl2 implements UserDao {

	@Override
	public void insert(User user) {
		System.out.println("用户["+user.toString()+"]被新增2");
	}
}

用户服务层：

public class UserService {
	//属性注入
	private UserDao userDao;
	public void setUserDao(UserDao userDao) {
		this.userDao = userDao;
	}
	
	//添加用户
	public void addUser(User user)
	{
		userDao.insert(user);
	}
}

applicationContext.xml

user使用的是基于构造函数的注入

userDao使用的基于属性的注入

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd">
    
    <bean id="user" class="cn.sjxy.domain.User">   
        <constructor-arg index="0" name="name" type="String" value="XXX" ></constructor-arg>
        <constructor-arg index="1" name="mobile" type="String" value="1534518XXXX" ></constructor-arg>
    </bean>
    <bean id="userDao" class="cn.sjxy.daoImpl.UserDaoImpl1">
    </bean>
   	<bean id="userService" class="cn.sjxy.service.UserService">   
        <property name="userDao" ref="userDao" ></property>
    </bean>
</beans>

测试代码：

public class SpringTest {
	public static void main(String[] args)
	{
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		
		//获取用户
		User user = (User)context.getBean("user");			
		System.out.println(user.toString());
		
		//获取用户业务类
		UserService userService = (UserService)context.getBean("userService");
		userService.addUser(user);
	}
}

3.2 基于构造函数的注入

Bank代码

public class Bank {
	private String bankName;
	private String bankNo;
	
	//构造函数注入
	public Bank(String bankName,String bankNo)
	{
		this.bankName = bankName;
		this.bankNo = bankNo;
	}
	
	public String toString() {
		return "[bankName="+this.bankName+";bankNo="+this.bankNo+"]";
	}
}

Address代码

public class Address {
	
	private String province;
	private String city;
	private String info;

	public String getProvince() {
		return province;
	}

	//属性注入
	public void setProvince(String province) {
		this.province = province;
	}

	public String getCity() {
		return city;
	}

	//属性注入
	public void setCity(String city) {
		this.city = city;
	}

	public String getInfo() {
		return info;
	}

	//属性注入
	public void setInfo(String info) {
		this.info = info;
	}
	
	public String toString()
	{
		return "[Province="+this.province+",City="+this.city+",info="+this.info+"]";
	}
}

Customer代码

public class Customer {
	private String id;
	private String name;
	private Address add;
	private Bank bank;
	
	//构造函数重载
	public Customer(String id,String name,Address add,Bank bank)
	{
		this.id = id;
		this.name = name;
		this.add = add;
		this.bank = bank;
	}
	
	public String toString()
	{
		return "id="+this.id+",name="+this.name+",add="+this.add+",bank="+this.bank+"";
	}
}

applicationContext配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd">
    
    <bean id="bank" class="cn.sjxy.domain.Bank">   
        <constructor-arg index="0" name="bankName" type="String" value="交通银行" ></constructor-arg>
        <constructor-arg index="1" name="bankNo" type="String" value="88888888" ></constructor-arg>
    </bean>
    <bean id="address" class="cn.sjxy.domain.Address">
    	<property name="province" value="江苏省"></property>
    	<property name="city" value="南京市"></property>
    	<property name="info" value="玄武区"></property>
    </bean>
   	<bean id="customer" class="cn.sjxy.domain.Customer">   
        <constructor-arg index="0" name="id" type="String" value="10001" ></constructor-arg>
        <constructor-arg index="1" name="name" type="String" value="王志瑞" ></constructor-arg>
        <constructor-arg index="2" name="add" ref="address" ></constructor-arg>
        <constructor-arg index="3" name="bank" ref="bank" ></constructor-arg>
    </bean>
</beans>