Spring IOC中对象的创建、策略及销毁时机和生命周期详解

package com.example.dao;
import com.example.pojo.Student;
public class StudentDaoImpl1 implements StudentDao{
    /*public StudentDaoImpl1() {
    }*/
    public StudentDaoImpl1(int a){};
    @Override
    public Student findById(int id){
        return new Student(id,"程序员","北京");
    }
}

package com.example.dao;
public class StudentDaoFactory {
    public StudentDao getStudentDao(){
        return new StudentDaoImpl1(1);
    }
}

    <!-- id: 工厂对象的id,class：工厂类 -->
    <bean id="studentDaoFactory" class="com.example.dao.StudentDaoFactory" />
    <!-- id:bean对象的id，factory-bean:工厂对象的id，factory-method：工厂方法 -->
    <bean id="studentDao" factory-bean="studentDaoFactory" factory-method="getStudentDao"></bean>

    @Test
    public void t2(){
        // 创建spring容器
        ApplicationContext ac = new FileSystemXmlApplicationContext("C:\\JavaProjects\\06SSM_Projects\\springdemo\\spring_ioc1\\src\\main\\resources\\bean.xml");
        // 从容器中获取对象
        StudentDao userDao = ac.getBean("studentDao",StudentDao.class);
        System.out.println(userDao);
        System.out.println(userDao.findById(1));;
    }

package com.example.dao;
public class StudentDaoFactory2 {
    public static StudentDao getStudentDao2() {
        return new StudentDaoImpl2();
    }
}

    <!-- id:bean的id class:工厂全类名 factory-method:工厂静态方法 -->
     <bean id="studentDao" class="com.example.dao.StudentDaoFactory2" factory-method="getStudentDao2"/>

    <bean id="studentDao" class="com.example.dao.StudentDaoImpl2" scope="singleton" lazy-init="true" />

    @Test
    public void t3(){
        // 创建Spring容器
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        // 从容器获取对象
        StudentDao studentDao1 = ac.getBean("studentDao",StudentDao.class);
        StudentDao studentDao2 = ac.getBean("studentDao",StudentDao.class);
        StudentDao studentDao3 = ac.getBean("studentDao",StudentDao.class);
        System.out.println(studentDao1.hashCode());
        System.out.println(studentDao2.hashCode());
        System.out.println(studentDao3.hashCode());
    }

<!-- 配置多例策略 -->
<bean id="studentDao" class="com.itbaizhan.dao.StudentDaoImpl2" scope="prototype"></bean>

    // 创建时自动执行的方法
    public void init(){
        System.out.println("使用StudentDaoImpl2创建对象"+this.hashCode());
    }
    // 销毁时自动执行的方法
    public void destroy(){
        System.out.println("销毁StudentDaoImpl2创建的对象"+this.hashCode());
    }

    <!-- init-method:创建对象时执行的方法 destroy-method:销毁对象时执行的方法 -->
    <bean id="studentDao" class="com.itbaizhan.dao.StudentDaoImpl2" scope="singleton" init-method="init" destroy-method="destory"></bean>

@Test
public void t3(){
  // 创建Spring容器
  ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("bean1.xml");
  // 销毁Spring容器，ClassPathXmlApplicationContext才有销毁容器的方法
  ac.close();
}

StudentDao studentDao = (StudentDao) ac.getBean("studentDao");

StudentDao studentDao2 = ac.getBean(StudentDao.class);

StudentDao studentDao2 = ac.getBean("studentDao",StudentDao.class);