Spring中IOC容器

IOC入门案例思路分析

1.管理什么（Service和Dao）

2.如何将管理的对象存放到IOC容器（配置applicationContext.xml）第二步

3.将管理的对象存放到IOC容器，如何获取IOC容器第三步

4.获取到IOC容器后，如何从容器中获取bean（即管理的对象）第四步

5.使用Spring导入坐标（pom.xml）第一步

基本内容

package com.huhu.dao;public interface BookDao {void save();
}

package com.huhu.dao.impl;import com.huhu.dao.BookDao;public class BookDaoImpl implements BookDao {public void save() {System.out.println("Bookdao save ....");}
}

package com.huhu.service;public interface BookService {void save();
}

package com.huhu.service.impl;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;public class BookServiceImpl implements BookService {private BookDao bookDao=new BookDaoImpl();public void save() {System.out.println("BookService save ....");bookDao.save();}
}

第一步：导入坐标

    <dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.10.RELEASE</version></dependency></dependencies>

第二步：配置bean

  <bean id="bookDao" class="com.huhu.dao.impl.BookDaoImpl"/><bean id="bookService" class="com.huhu.service.impl.BookServiceImpl"/>

第三步：获取IOC容器和第四步：获取bean

package com.huhu;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App2 {public static void main(String[] args) {ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");BookDao bookDao = (BookDao) ctx.getBean("bookDao");bookDao.save();System.out.println();BookService bookService = (BookService) ctx.getBean("bookService");bookService.save();}
}

实现结果：

DI 入门案例

基本内容与上面差不多，唯一修改的就是BookServiceImpl类

package com.huhu.service.impl;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;public class BookServiceImpl implements BookService {private BookDao bookDao;public void save() {System.out.println("BookService save ....");bookDao.save();}public void setBookDao(BookDao bookDao) {this.bookDao = bookDao;}
}

bean配置 ref中bookDao与bookDaoImpl类注入bean定义id属性值bookDao一致

    <bean id="bookDao" class="com.huhu.dao.impl.BookDaoImpl"/><bean id="bookService" class="com.huhu.service.impl.BookServiceImpl"><property name="bookDao" ref="bookDao"/></bean>

测试结果依旧不变

bean起别名添加name属性

获取bean可以使用name属性值也可以id属性值（建议id）

<bean id="bookDao" name="dao" class="com.huhu.dao.impl.BookDaoImpl"/><bean id="bookService" class="com.huhu.service.impl.BookServiceImpl"><property name="bookDao" ref="dao"/></bean>

bean作用范围配置默认单例

package com.huhu;import com.huhu.dao.BookDao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App {public static void main(String[] args) {ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");BookDao bookDao = (BookDao) ctx.getBean("bookDao");BookDao bookDao2 = (BookDao) ctx.getBean("bookDao");System.out.println(bookDao);System.out.println(bookDao2);}
}

修改单例的话在配置文件编辑scope域=prototype

<bean id="bookDao" name="dao" class="com.huhu.dao.impl.BookDaoImpl" scope="prototype"/><bean id="bookService" class="com.huhu.service.impl.BookServiceImpl"><property name="bookDao" ref="dao"/></bean>

bean创建方式

第一种：默认无参构造方法（可不写）（private也可以被调用使用反射）一旦加了有参就必须写上无参构造方法

<bean id="bookDao" name="dao" class="com.huhu.dao.impl.BookDaoImpl"/>

public class BookDaoImpl implements BookDao {private BookDaoImpl(int i){System.out.println("Bookdao constructor is running...");}public void save() {System.out.println("Bookdao save ....");}
}

没有无参构造方法后，报错Caused by: java.lang.NoSuchMethodException: com.huhu.dao.impl.BookDaoImpl.<init>()

第二种：静态工厂（早期使用最多，了解即可）（基本内容如下）

package com.huhu.dao;public interface OrderDao {void save();
}

package com.huhu.dao.impl;import com.huhu.dao.OrderDao;public class OrderDaoImpl implements OrderDao {public void save() {System.out.println("OrderDao save ...");}
}

package com.huhu.factory;import com.huhu.dao.OrderDao;
import com.huhu.dao.impl.OrderDaoImpl;public class OrderDaoFactory {public static OrderDao getOrderDao(){return new OrderDaoImpl();}
}

package com.huhu;import com.huhu.dao.OrderDao;
import com.huhu.factory.OrderDaoFactory;public class AppForInstanceOrder {public static void main(String[] args) {//通过静态工厂创建对象OrderDao orderDao = OrderDaoFactory.getOrderDao();orderDao.save();}
}

使用静态工厂实例化bean

<!--使用静态工厂实例化bean--><bean id="orderDao" class="com.huhu.factory.OrderDaoFactory" factory-method="getOrderDao"/>

package com.huhu;import com.huhu.dao.OrderDao;
import com.huhu.factory.OrderDaoFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class AppForInstanceOrder {public static void main(String[] args) {//通过静态工厂创建对象
//        OrderDao orderDao = OrderDaoFactory.getOrderDao();
//        orderDao.save();ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");OrderDao orderDao = (OrderDao) ctx.getBean("orderDao");orderDao.save();}
}

第三种：实例工厂（基本内容如下）

package com.huhu.dao;public interface UserDao {void save();
}

package com.huhu.dao.impl;import com.huhu.dao.UserDao;public class UserDaoImpl implements UserDao {public void save() {System.out.println("UserDao save ...");}
}

package com.huhu.factory;import com.huhu.dao.UserDao;
import com.huhu.dao.impl.UserDaoImpl;public class UserDaoFactory {public UserDao getUserDao(){return new UserDaoImpl();}
}

package com.huhu;import com.huhu.dao.UserDao;
import com.huhu.factory.UserDaoFactory;public class AppForInstanceUser {public static void main(String[] args) {UserDaoFactory userDaoFactory = new UserDaoFactory();UserDao userDao = userDaoFactory.getUserDao();userDao.save();}
}

使用实例工厂实例化bean

<!--使用实例工厂实例化bean--><bean id="userFactory" class="com.huhu.factory.UserDaoFactory"/><bean id="userDao" factory-method="getUserDao" factory-bean="userFactory"/>

package com.huhu;import com.huhu.dao.UserDao;
import com.huhu.factory.UserDaoFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class AppForInstanceUser {public static void main(String[] args) {
//        UserDaoFactory userDaoFactory = new UserDaoFactory();
//        UserDao userDao = userDaoFactory.getUserDao();
//        userDao.save();ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");UserDao userDao = (UserDao) ctx.getBean("userDao");userDao.save();}
}

优化创建UserDaoFactoryBean类代替UserDaoFactory类（实用）

package com.huhu.factory;import com.huhu.dao.UserDao;
import com.huhu.dao.impl.UserDaoImpl;
import org.springframework.beans.factory.FactoryBean;public class UserDaoFactoryBean implements FactoryBean<UserDao> {//代替原始实例工厂中创建对象的方法public UserDao getObject() throws Exception {return new UserDaoImpl();}//获取对象类型public Class<?> getObjectType() {return UserDao.class;}
}

<!--使用FactoryBean实例化bean--><bean id="userDao" class="com.huhu.factory.UserDaoFactoryBean"/>

bean生命周期

暴力关闭容器（实际开发不使用）

package com.huhu.dao.impl;import com.huhu.dao.BookDao;public class BookDaoImpl implements BookDao {public void save() {System.out.println("Bookdao save ....");}public void init(){System.out.println("init ...");}public void destroy(){System.out.println("destroy ...");}
}

<bean id="bookDao" name="dao" class="com.huhu.dao.impl.BookDaoImpl" init-method="init" destroy-method="destroy"/>

ClassPathXmlApplicationContext子类型替代ApplicationContext父类型，才可关闭容器

package com.huhu;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App2 {public static void main(String[] args) {ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");BookDao bookDao = (BookDao) ctx.getBean("dao");bookDao.save();ctx.close();}
}

设置关闭钩子（哪个位置都可以）在虚拟机退出前先关闭容器在退出虚拟机

package com.huhu;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App2 {public static void main(String[] args) {ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");BookDao bookDao = (BookDao) ctx.getBean("dao");bookDao.save();
//        ctx.close();ctx.registerShutdownHook();}
}

优化篇实现接口（了解即可）

<bean id="bookService" class="com.huhu.service.impl.BookServiceImpl"><property name="bookDao" ref="dao"/></bean>

package com.huhu.service.impl;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;public class BookServiceImpl implements BookService, InitializingBean, DisposableBean {private BookDao bookDao;public void save() {System.out.println("BookService save ....");bookDao.save();}public void setBookDao(BookDao bookDao) {System.out.println("set...");this.bookDao = bookDao;}public void destroy() throws Exception {System.out.println("BookService destroy ...");}public void afterPropertiesSet() throws Exception {System.out.println("BookService init ...");}
}

package com.huhu;import com.huhu.dao.BookDao;
import com.huhu.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class App2 {public static void main(String[] args) {ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");BookDao bookDao = (BookDao) ctx.getBean("dao");bookDao.save();
//        ctx.close();ctx.registerShutdownHook();}
}

结果如下：

总结：初始化容器

步骤：1创建对象 2执行构造方法 3执行属性注入（set）4执行bean初始化方法

使用bean：执行业务操作

关闭/销毁容器：执行bean销毁方法（容器关闭前触发bean的销毁）