Spring Bean - xml 配置文件创建对象

类型：

1、值类型

2、null （标签）

3、特殊符号 （<   -> &lt; ）

4、CDATA 

<?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">

    <!--   引用外部bean-->
    <bean id="school" class="com.gyk.ObjInject.School">
        <property name="location" value="henan"></property>
        <property name="num" value="30000"></property>
    </bean>
    <bean id="school2" class="com.gyk.ObjInject.School">
        <property name="location" value="henan"></property>
        <property name="num" value="30000"></property>
    </bean>
    <!--    <bean id="student" class="com.gyk.ObjInject.Student">-->
    <!--        <property name="name" value="zs"></property>-->
    <!--        <property name="age" value="22"></property>-->
    <!--        <property name="school" ref="school"></property>-->
    <!--    </bean>-->

    <!--   嵌套内部bean-->
    <bean id="student" class="com.gyk.ObjInject.Student">
        <property name="name" value="zs"></property>
        <property name="age" value="22"></property>
        <!--  对象属性-->
        <property name="school">
            <bean class="com.gyk.ObjInject.School">
                <property name="location" value="henan"></property>
                <property name="num" value="30000"></property>
            </bean>
        </property>
        <!-- 设置数组属性-->
        <property name="hobbies">
            <array>
                <value>play</value>
                <value>sing</value>
                <value>ball</value>
            </array>
        </property>
        <!-- 设置 list 属性-->
        <property name="schoolList">
            <list>
                <ref bean="school"></ref>
                <ref bean="school2"></ref>
            </list>
        </property>
        <!--        设置map 属性-->
        <property name="stringSchoolMap">
            <list>
                <map>
                    <entry>
                        <key>
                            <value>map1</value>
                        </key>
                        <ref bean="school"></ref>
                    </entry>
                </map>
                <map>
                    <entry>
                        <key>
                            <value>map2</value>
                        </key>
                        <ref bean="school2"></ref>
                    </entry>
                </map>
            </list>
        </property>
    </bean>


</beans>

package com.gyk.ObjInject;

import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.Arrays;
import java.util.List;
import java.util.Map;

/**
 * ClassName: Student
 * Package: com.gyk.depInject
 * Description:
 *
 * @Author Samuel
 * @Create 2024/7/24 09:20
 * @Version 1.0
 */
public class Student {
    private String name;
    private int age;
    private School school;

    private String[] hobbies;

    private List<School> schoolList;


    private List<Map<String, School>> stringSchoolMap;

    public void setStringSchoolMap(List<Map<String, School>> stringSchoolMap) {
        this.stringSchoolMap = stringSchoolMap;
    }

    public void setSchoolList(List<School> schoolList) {
        this.schoolList = schoolList;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setHobbies(String[] hobbies) {
        this.hobbies = hobbies;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setSchool(School school) {
        this.school = school;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", school=" + school +
                ", hobbies=" + Arrays.toString(hobbies) +
                ", schoolList=" + schoolList +
                ", stringSchoolMap=" + stringSchoolMap +
                '}';
    }

    @Test
    public void getObj() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("ObjInject.xml");
        System.out.println(applicationContext.getBean(Student.class));
    }

    public void setSchoolNum(int num) {
        this.school.setNum(num);
    }

}

package com.gyk.ObjInject;

/**
 * ClassName: School
 * Package: com.gyk.depInject
 * Description:
 *
 * @Author Samuel
 * @Create 2024/7/24 09:21
 * @Version 1.0
 */
public class School {
    private String location;
    private int num;

    public void setLocation(String location) {
        this.location = location;
    }

    public void setNum(int num) {
        this.num = num;
    }

    @Override
    public String toString() {
        return "School{" +
                "location='" + location + '\'' +
                ", num=" + num +
                '}';
    }
}


2024-07-24 14:09:02 534 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@49872d67
2024-07-24 14:09:02 602 [main] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 3 bean definitions from class path resource [ObjInject.xml]
2024-07-24 14:09:02 615 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'school'
2024-07-24 14:09:02 633 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'school2'
2024-07-24 14:09:02 633 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'student'
Student{name='zs', age=22, school=School{location='henan', num=30000}, hobbies=[play, sing, ball], schoolList=[School{location='henan', num=30000}, School{location='henan', num=30000}], stringSchoolMap=[{map1=School{location='henan', num=30000}}, {map2=School{location='henan', num=30000}}]}

util:list  util:map

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:util="http://www.springframework.org/schema/util"
       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
       http://www.springframework.org/schema/util
       http://www.springframework.org/schema/util/spring-util.xsd">


    <util:list id="list">
        <ref bean="school"></ref>
        <ref bean="school2"></ref>
    </util:list>


    <util:list id="list2">
        <util:map id="map">
            <entry>
                <key>
                    <value>school1</value>
                </key>
                <ref bean="school"></ref>
            </entry>
            <entry>
                <key>
                    <value>school2</value>
                </key>
                <ref bean="school2"></ref>
            </entry>
        </util:map>
    </util:list>


 <property name="schoolList" ref="list">
            <!--            <list>-->
            <!--                <ref bean="school"></ref>-->
            <!--                <ref bean="school2"></ref>-->
            <!--            </list>-->
  </property>

p命名空间 

    <!--   p命名空间  -->
    <bean id="school3" class="com.gyk.ObjInject.School" p:num="11" p:location="ww">
    </bean>
    <bean id="student2" class="com.gyk.ObjInject.Student" p:age="11" p:name="e11" p:hobbies="{1},{1}"
          p:schoolList-ref="list"
          p:stringSchoolMap-ref="list2">
    </bean>

bean 中读取本地 properties配置属性文件    druid 读取配置属性

先加依赖

 <!-- MySQL驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.30</version>
        </dependency>

        <!-- 数据源 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.15</version>
        </dependency>

注意配置 context 命名空间url 和 xsi location url。

 @Test
    public void getPropertiesInfo() throws SQLException {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("ObjInject.xml");
        DruidDataSource student = (DruidDataSource) applicationContext.getBean(DruidDataSource.class);
        System.out.println(student.getUrl());
        System.out.println(student.getUsername());
        System.out.println(student.getPassword());
//        System.out.println(student.getConnection());
        System.out.println(student.getCreatedTime());
    }



jdbc:mysql://localhost:3306/testdb?serverTimezone=UTC
root
root
Thu Jul 25 11:20:26 CST 2024

bean的作用范围：单实例还是多实例 （默认 singleon 单实例）

Bean 生命周期

    /**
     * bean life cycle
     * 1. invoke null params controller
     * 2. set obj property
     * 3. before init
     * 4. invoke init method
     * 5. after init
     * 6. obj init success
     * 7. obj destroy
     * 8. ioc close
     */

 

①具体的生命周期过程

• bean对象创建（调用无参构造器）

• 给bean对象设置属性

• bean的后置处理器（初始化之前）

• bean对象初始化（需在配置bean时指定初始化方法）

• bean的后置处理器（初始化之后）

• bean对象就绪可以使用

• bean对象销毁（需在配置bean时指定销毁方法）

• IOC容器关闭

注意其中的initMethod()和destroyMethod()，可以通过配置bean指定为初始化和销毁的方法

<!-- 使用init-method属性指定初始化方法 -->
<!-- 使用destroy-method属性指定销毁方法 -->
<bean class="com.atguigu.spring6.bean.User" scope="prototype" 
init-method="initMethod" destroy-method="destroyMethod">
    <property name="id" value="1001"></property>
    <property name="username" value="admin"></property>
    <property name="password" value="123456"></property>
    <property name="age" value="23"></property>
</bean>

⑤bean的后置处理器

bean的后置处理器会在生命周期的初始化前后添加额外的操作，需要实现BeanPostProcessor接口，且配置到IOC容器中，需要注意的是，bean后置处理器不是单独针对某一个bean生效，而是针对IOC容器中所有bean都会执行

public class MyBeanProcessor implements BeanPostProcessor {
    
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("☆☆☆" + beanName + " = " + bean);
        return bean;
    }
    
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("★★★" + beanName + " = " + bean);
        return bean;
    }
}

<!--        **⑤bean的后置处理器**-->
<!--        bean的后置处理器会在生命周期的初始化前后添加额外的操作，需要实现BeanPostProcessor接口，且配置到IOC容器中，需要注意的是，bean后置处理器不是单独针对某一个bean生效，而是针对IOC容器中所有bean都会执行-->

 FactoryBean

FactoryBean是Spring提供的一种整合第三方框架的常用机制。和普通的bean不同，配置一个FactoryBean类型的bean，在获取bean的时候得到的并不是class属性中配置的这个类的对象，而是getObject()方法的返回值。通过这种机制，Spring可以帮我们把复杂组件创建的详细过程和繁琐细节都屏蔽起来，只把最简洁的使用界面展示给我们。

将来我们整合Mybatis时，Spring就是通过FactoryBean机制来帮我们创建SqlSessionFactory对象的。

class MyOBJ {

}

public class FactoryBean implements org.springframework.beans.factory.FactoryBean<MyOBJ> {
    @Override
    public MyOBJ getObject() throws Exception {
        return new MyOBJ();
    }

    @Override
    public Class<?> getObjectType() {
        return MyOBJ.class;
    }

    @Test
    public void re() {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("FactoryBean.xml");
        MyOBJ factoryBean = (MyOBJ) context.getBean("factoryBean"); //只能传id ，FactoryBean.class 会报错
        System.out.println(factoryBean);//com.gyk.factory.MyOBJ@7df587ef
    }
}

基于xml自动装配

使用bean标签的autowire属性设置自动装配效果

自动装配方式：byType

byType：根据类型匹配IOC容器中的某个兼容类型的bean，为属性自动赋值

若在IOC中，没有任何一个兼容类型的bean能够为属性赋值，则该属性不装配，即值为默认值null

若在IOC中，有多个兼容类型的bean能够为属性赋值，则抛出异常NoUniqueBeanDefinitionException

  <bean id="controller" class="com.gyk.auto_wired.controller.controller" autowire="byType"></bean>
    <bean id="service" class="com.gyk.auto_wired.service.service" autowire="byType"></bean>
    <bean id="dao" class="com.gyk.auto_wired.dao.dao" autowire="byType"></bean>

public class controller {
    public void setServ(service serv) {
        this.serv = serv;
    }

    private service serv;

    public void run() {
        System.out.println("controller run ");
        serv.run();
    }

    @Test
    public void test() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("autowire.xml");
        controller c = (controller) applicationContext.getBean(controller.class);
        c.run();
    }
}


//
public class service {
    private dao d;

    public void setD(dao d) {
        this.d = d;
    }

    public void run() {
        System.out.println(" service run ");
        d.run();
    }
}
// 

public class dao {
    public void run() {
        System.out.println(" dao run ");
    }
}