控制反转AOP

1. 控制反转-Inversion Of Control

	* ioc 的作用：
		削减计算机程序的耦合(解除我们代码中的依赖关系)。
	* 准备环境
		1. 创建业务层接口和实现类
			public interface IAccountService {
				/**
				* 保存账户（此处只是模拟，并不是真的要保存）
				*/
				void saveAccount();
			}
			public class AccountServiceImpl implements IAccountService {
				/*private IAccountDao accountDao = new AccountDaoImpl();
				//此处的依赖关系有待解决*/
				private IAccountDao accountDao;
				@Override
				public void saveAccount() {
					accountDao.saveAccount();
				} 
			}
		2. 创建持久层接口和实现类
			public interface IAccountDao {
				/**
				* 保存账户
				*/
				void saveAccount();
			}
			public class AccountDaoImpl implements IAccountDao {
				@Override
				public void saveAccount() {
					System.out.println("保存了账户");
				} 
			}
		3. 在pom.xml 中导入 jar 包
			<dependency>
	            <dependency>
		            <groupId>org.springframework</groupId>
		            <artifactId>spring-context</artifactId>
		            <version>5.0.2.RELEASE</version>
		        </dependency>
		        <dependency>
		            <groupId>org.springframework</groupId>
		            <artifactId>spring-test</artifactId>
		            <version>5.0.2.RELEASE</version>
		        </dependency>
		        <dependency>
		            <groupId>commons-dbutils</groupId>
		            <artifactId>commons-dbutils</artifactId>
		            <version>1.4</version>
		        </dependency>

		        <dependency>
		            <groupId>mysql</groupId>
		            <artifactId>mysql-connector-java</artifactId>
		            <version>5.1.6</version>
		        </dependency>

		        <dependency>
		            <groupId>c3p0</groupId>
		            <artifactId>c3p0</artifactId>
		            <version>0.9.1.2</version>
		        </dependency>

		        <dependency>
		            <groupId>junit</groupId>
		            <artifactId>junit</artifactId>
		            <version>4.12</version>
		        </dependency>
		    </dependency>

	1. 基于 XML 的配置
		1.1: 在类的根路径下创建一个任意名称的 xml 文件
			bean.xml
				给配置文件导入约束：
					<?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 
						http://www.springframework.org/schema/beans/spring-beans.xsd"
						<!-- default-lazy-init="true" 延时所有的实例化对象 -->
						>
					</beans>
		1.2 让 spring 管理资源，在配置文件中配置 service 和 dao
			<!-- bean 标签：用于配置让 spring 创建对象，并且存入 ioc 容器之中
				id 属性：对象的唯一标识。
				class 属性：指定要创建对象的全限定类名
			-->
			<!-- 配置 service --> 
			<bean id="accountService" class="com.demos.service.impl.AccountServiceImpl">
			</bean>
			<!-- 配置 dao --> 
			<bean id="accountDao" class="com.demos.dao.impl.AccountDaoImpl"></bean>
		1.3 测试配置是否成功
			public class Client {
				/**
				* 使用 main 方法获取容器测试执行
				*/
			public static void main(String[] args) {
				// 1.获取核心容器对象
				ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
	   			ApplicationContext ac = new 
	     			 FileSystemXmlApplicationContext("C:\\Users\\zhy\\Desktop\\bean.xml");
				// 2.根据id获取Bean对象
				IAccountService as = (IAccountService) ac.getBean("accountService");
				IAccountDao adao = ac.getBean("accountDao", IAccountDao.class);

				System.out.println(as);
				System.out.println(adao);
				adao.saveAccount();

				//ac.getClass().getMethod("close", null).invoke(ap, null);
			} }
		1.4 结果
			com.demos.service.impl.AccountServiceImpl@5c7fa833
			com.demos.dao.impl.AccountDaoImpl@39aeed2f
			保存了账户

		1.5  配置对象(取消 new 关键字) bean.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"
				xsi:schemaLocation="http://www.springframework.org/schema/beans
				http://www.springframework.org/schema/beans/spring-beans.xsd">
				<!-- 配置 service --> 
				<bean id="accountService" 
					class="com.demos.service.impl.AccountServiceImpl"> 
					<property name="accountDao" ref="accountDao"></property>
				</bean>
				<!--配置Dao对象-->
			    <bean id="accountDao" class="com.demos.dao.impl.AccountDaoImpl">
			        <!-- 注入QueryRunner -->
			        <property name="runner" ref="runner"></property>
			    </bean>

			    <!--配置QueryRunner-->
			    <bean id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype">
			        <!--注入数据源-->
			        <constructor-arg name="ds" ref="dataSource"></constructor-arg>
			    </bean>
				<!-- 配置数据源 --> 
				<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> 
					<property name="driverClass" value="com.mysql.jdbc.Driver"></property> 
					<property name="jdbcUrl" value="jdbc:mysql:///spring_day02"></property> 
					<property name="user" value="root"></property> 
					<property name="password" value="1234"></property>
				</bean>
			</beans>