Spring之IOC

发布时间：2024年01月01日

1 IOC介绍

IOC(Inversion Of Control)，即控制反转，是一种能够指导我们设计出松耦合、高可扩展应用程序的设计思想。

反转的是什么
正常情况下，我们会主动创建对象，然后再使用，对象的生命周期有我们通过编码控制。
而IOC思想是将对象的创建及对对象之间关系的维护交由第三方容器实现，反转的正式这个方面的内容。
实现方式
DI(Dependency Injection)，即依赖注入，是实现IOC的一种方式，指Spring创建对象的过程中，将对象依赖属性通过配置进行注入。
IOC 就是一种控制反转的思想，而 DI 是对IoC的一种具体实现。

2 Spring

Spring框架提供了IOC容器相关的实现方式，Spring通过IOC容器管理Bean及Bean之间的依赖关系，其实现方式包括如下两种：

BeanFactory
这是 IoC 容器的基本实现，是 Spring 内部使用的接口。面向 Spring 本身，不提供给开发人员使用。
ApplicationContext
BeanFactory 的子接口，提供了更多高级特性。面向 Spring 的使用者，几乎所有场合都使用 ApplicationContext 而不是底层的 BeanFactory。

类型名	说明
ClassPathXmlApplicationContext	通过读取类路径下的 XML 格式的配置文件创建 IOC 容器对象
FileSystemXmlApplicationContext	通过文件系统路径读取 XML 格式的配置文件创建 IOC 容器对象

Spring管理bean的两种方式：xml方式和注解

3 Spring基于xml管理bean

3.1 基础环境搭建

创建子模块giser-java-spring6-01，并引入配置文件beans.xml、log4j2.xml，添加如下依赖：

<dependencies>
	<!-- Spring依赖 -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>6.1.1</version>
    </dependency>

    <!--junit5测试-->
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-api</artifactId>
        <version>5.10.1</version>
    </dependency>

    <!--log4j2的依赖-->
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.19.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j2-impl</artifactId>
        <version>2.19.0</version>
    </dependency>
</dependencies>

创建实体类：

public class HelloWorld {
    public HelloWorld(){
        System.out.println("constructor execute...");
    }
    public void sayHello(){
        System.out.println("hello world!");
    }
}

beans.xml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 http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--
        向Spring容器中注册bean信息
        id: 注册的bean的id，作为bean的唯一标识
        class: 注册bean的类全路径，用户创建bean对象
    -->
    <bean id="helloWorld" class="com.giser.spring6.HelloWorld"></bean>

</beans>

log4j配置：

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <loggers>
        <!--
            level指定日志级别，从低到高的优先级：
                TRACE < DEBUG < INFO < WARN < ERROR < FATAL
                trace：追踪，是最低的日志级别，相当于追踪程序的执行
                debug：调试，一般在开发中，都将其设置为最低的日志级别
                info：信息，输出重要的信息，使用较多
                warn：警告，输出警告的信息
                error：错误，输出错误信息
                fatal：严重错误
        -->
        <root level="DEBUG">
            <appender-ref ref="spring6log"/>
            <appender-ref ref="RollingFile"/>
            <appender-ref ref="log"/>
        </root>
    </loggers>

    <appenders>
        <!--输出日志信息到控制台-->
        <console name="spring6log" target="SYSTEM_OUT">
            <!--控制日志输出的格式-->
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss SSS} [%t] %-3level %logger{1024} - %msg%n"/>
        </console>

        <!--文件会打印出所有信息，这个log每次运行程序会自动清空，由append属性决定，适合临时测试用-->
        <File name="log" fileName="d:/spring6_log/test.log" append="false">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} %-5level %class{36} %L %M - %msg%xEx%n"/>
        </File>

        <!-- 这个会打印出所有的信息，
            每次大小超过size，
            则这size大小的日志会自动存入按年份-月份建立的文件夹下面并进行压缩，
            作为存档-->
        <RollingFile name="RollingFile" fileName="d:/spring6_log/app.log"
                     filePattern="log/$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log.gz">
            <PatternLayout pattern="%d{yyyy-MM-dd 'at' HH:mm:ss z} %-5level %class{36} %L %M - %msg%xEx%n"/>
            <SizeBasedTriggeringPolicy size="50MB"/>
            <!-- DefaultRolloverStrategy属性如不设置，
            则默认为最多同一文件夹下7个文件，这里设置了20 -->
            <DefaultRolloverStrategy max="20"/>
        </RollingFile>
    </appenders>
</configuration>

3.2 获取bean的三种方式

public class HelloWorldTest {
    private Logger logger = LoggerFactory.getLogger(HelloWorldTest.class);
    @Test
    public void testSpringBean() {
        // 读取配置信息
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
    }
}

根据bean标签的id获取

// 根据id获取bean
HelloWorld bean1 = (HelloWorld) applicationContext.getBean("helloWorld");

根据bean的类型获取

// 根据bean的类型获取bean,此时要求此类型的bean只能存在一个，否则会抛异常
HelloWorld bean2 = applicationContext.getBean(HelloWorld.class);

根据id和类型获取bean

HelloWorld bean3 = applicationContext.getBean("helloWorld", HelloWorld.class);

3.3 DI之setter注入

实体：

public class User {
    private String userName;
    private Integer userAge;
    // 无参构造函数
    // 全参构造函数
    // getter setter toString
}

beans-di.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">
    <!--
        set方法注入
    -->
    <bean id="user" class="com.giser.spring6.entity.User">
        <property name="userName" value="张三"/>
        <property name="userAge" value="13" />
    </bean>

</beans>

测试

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-di.xml");
        User user = applicationContext.getBean("user", User.class);

3.4 DI之构造器注入

    <!--
        constructor注入
        name: 指定参数名
        value: 参数值
        index属性：指定参数所在位置的索引（从0开始）
    -->
    <bean id="user1" class="com.giser.spring6.entity.User">
        <constructor-arg name="userName" value="张三" />
        <constructor-arg name="userAge" value="23" />
    </bean>

测试

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-di.xml");
        User user1 = applicationContext.getBean("user1", User.class);

3.5 DI之特殊值注入


    <!--
        特殊值处理：字面量赋值
    -->
    <!-- 使用value属性给bean的属性赋值时，Spring会把value属性的值看做字面量 -->
    <bean id="user2" class="com.giser.spring6.entity.User">
        <property name="userName" value="张三"/>
        <property name="userAge" value="13" />
    </bean>

    <!--
        特殊值处理：null值
    -->
    <bean id="user3" class="com.giser.spring6.entity.User">
        <property name="userName">
            <null />
        </property>
        <property name="userAge" value="13" />
    </bean>

    <!--
        特殊值处理：xml实体
    -->
    <bean id="user4" class="com.giser.spring6.entity.User">
        <property name="userName" value="a &lt; b"></property>
        <property name="userAge" value="13" />
    </bean>

    <!--
        特殊值处理：CDATA节
            CDATA中的C代表Character，是文本、字符的含义，CDATA就表示纯文本数据;
            XML解析器看到CDATA节就知道这里是纯文本，就不会当作XML标签或属性来解析;
            所以CDATA节中写什么符号都随意;
    -->
    <bean id="user5" class="com.giser.spring6.entity.User">
        <property name="userName">
            <value><![CDATA[A<=B]]></value>
        </property>
        <property name="userAge" value="13" />
    </bean>

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-di.xml");
User user2 = applicationContext.getBean("user2", User.class);
User user3 = applicationContext.getBean("user3", User.class);
User user4 = applicationContext.getBean("user4", User.class);
User user5 = applicationContext.getBean("user5", User.class);
logger.info("特殊值处理-字面量赋值：{}", user2);
logger.info("特殊值处理-null值：{}", user3);
logger.info("特殊值处理-xml实体：{}", user4);
logger.info("特殊值处理-CDATA节：{}", user5);

3.6 DI之对象类型赋值

包括三种方式：引入外部bean、使用内部bean、级联属性赋值。
实体：

public class Dept {
    private String deptName;
    // getter setter toString
}

public class Emp {

    private String empName;
    private Integer empAge;
    private Dept dept;
    // getter setter toString
}

xml文件

<?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">

    <!--
        对象类型赋值方式一：引入外部bean
    -->
    <bean id="dept" class="com.giser.spring6.iocpojo.Dept">
        <property name="deptName" value="产品研发部" />
    </bean>

    <bean id="emp1" class="com.giser.spring6.iocpojo.Emp">
        <property name="empName" value="小明" />
        <property name="empAge" value="32" />
        <!-- 对象类型属性，通过ref引入外部bean -->
        <property name="dept" ref="dept" />
    </bean>

    <!--
        对象类型赋值方式二：使用内部bean
    -->
    <bean id="emp2" class="com.giser.spring6.iocpojo.Emp">
        <property name="empName" value="小明" />
        <property name="empAge" value="32" />
        <!-- 对象类型属性，使用内部bean -->
        <property name="dept" >
            <!-- 内部bean只能用于给属性赋值，不能在外部通过IOC容器获取，因此可以省略id属性 -->
            <bean class="com.giser.spring6.iocpojo.Dept">
                <property name="deptName" value="董事会" />
            </bean>
        </property>
    </bean>

    <!--
        对象类型赋值方式三：级联属性赋值
    -->
    <bean id="dept3" class="com.giser.spring6.iocpojo.Dept">
        <property name="deptName" value="产品研发部" />
    </bean>
    <bean id="emp3" class="com.giser.spring6.iocpojo.Emp">
        <property name="empName" value="小明" />
        <property name="empAge" value="32" />
        <!-- 对象类型属性，级联属性赋值 -->
        <property name="dept" ref="dept3" />
        <property name="dept.deptName" value="中央办公室" />
    </bean>

</beans>

测试：

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-obj-di.xml");
Emp emp = applicationContext.getBean("emp3", Emp.class);
logger.info("对象类型属性赋值：{}", emp);

3.7 DI之数组类型属性赋值

public class Student {

    private String stuName;
    private String[] hobbyArr;

    // 无参构造函数
    // 全参构造函数
    // getter setter toString
}

<?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">

    <!--
        数组类型属性赋值
    -->
    <bean id="stu" class="com.giser.spring6.iocarray.Student">
        <property name="stuName" value="张三" />
        <property name="hobbyArr">
            <array>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>敲代码</value>
            </array>
        </property>
    </bean>

</beans>

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-arr-di.xml");
Student stu = applicationContext.getBean("stu", Student.class);
logger.info("数组类型属性赋值：{}", stu);

3.8 DI之List类型属性赋值

public class Cls {
    private List<Stu> stuList;
    private String clsName;

    // 无参构造函数
    // 全参构造函数
    // getter setter toString
}

public class Stu {
    private String stuName;
    private List<String> hobbyList;

    // 无参构造函数
    // 全参构造函数
    // getter setter toString
}

<?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">

    <!--
        数组类型属性赋值：基本类型
    -->
    <bean id="stu" class="com.giser.spring6.ioclist.Stu">
        <property name="stuName" value="张三" />
        <property name="hobbyList">
            <list>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>敲代码</value>
            </list>
        </property>
    </bean>

    <bean id="stu2" class="com.giser.spring6.ioclist.Stu">
        <property name="stuName" value="李四" />
        <property name="hobbyList">
            <list>
                <value>烧烤</value>
                <value>炸鸡</value>
                <value>胡辣汤</value>
            </list>
        </property>
    </bean>

    <!--
    数组类型属性赋值: 引用类型
    -->
    <bean id="cls" class="com.giser.spring6.ioclist.Cls">
        <property name="clsName" value="中一班" />
        <property name="stuList">
            <list>
                <ref bean="stu" />
                <ref bean="stu2" />
            </list>
        </property>
    </bean>

</beans>

private Logger logger = LoggerFactory.getLogger(SpringListDITest.class);

@Test
public void testSpecialVal(){
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-list-di.xml");
    Stu stu = applicationContext.getBean("stu", Stu.class);
    logger.info("List集合类型属性赋值：{}", stu);
}

@Test
public void testSpecialVal2(){
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-list-di.xml");
    Cls cls = applicationContext.getBean("cls", Cls.class);
    logger.info("List集合类型属性赋值：{}", cls);
}

3.9 DI之Map类型属性赋值

public class Family {

    private String familyName;
    private Map<String, Mem> memMap;

    // 无参构造函数
    // 全参构造函数
    // getter setter toString
}

public class Mem {
    private String memName;
    private Integer memAge;    
    // 无参构造函数
    // 全参构造函数
    // getter setter toString
}

<?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">

    <!--
        数组类型属性赋值：基本类型
    -->
    <bean id="mem1" class="com.giser.spring6.iocmap.Mem">
        <property name="memAge" value="11" />
        <property name="memName" value="小李" />
    </bean>

    <bean id="mem2" class="com.giser.spring6.iocmap.Mem">
        <property name="memAge" value="22" />
        <property name="memName" value="小张"/>
    </bean>

    <!--
    数组类型属性赋值: 引用类型
    -->
    <bean id="family" class="com.giser.spring6.iocmap.Family">
        <property name="familyName" value="梦想家" />
        <property name="memMap">
            <map>
                <entry>
                    <key>
                        <value>1001</value>
                    </key>
                    <ref bean="mem1"/>
                </entry>
                <entry>
                    <key>
                        <value>1002</value>
                    </key>
                    <ref bean="mem2"/>
                </entry>
            </map>
        </property>
    </bean>

    <bean id="family2" class="com.giser.spring6.iocmap.Family">
        <property name="familyName" value="梦想家" />
        <property name="memMap">
            <map>
                <entry value-ref="mem1">
                    <key>
                        <value>1001</value>
                    </key>
                </entry>
                <entry value-ref="mem2">
                    <key>
                        <value>1002</value>
                    </key>
                </entry>
            </map>
        </property>
    </bean>

</beans>

public class SpringMapDITest {

    private Logger logger = LoggerFactory.getLogger(SpringMapDITest.class);

    @Test
    public void testSpecialVal(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-map-di.xml");
        Family family = applicationContext.getBean("family", Family.class);
        logger.info("对象类型属性赋值：{}", family);
        Family family2 = applicationContext.getBean("family2", Family.class);
        logger.info("对象类型属性赋值：{}", family2);
    }

}

3.10 DI之引用集合类型注入

public class Family {

    private String familyName;
    private Map<String, Mem> memMap;

    private List<Mem> memList;
    // 无参构造函数
    // 全参构造函数
    // getter setter toString

public class Mem {
    private String memName;
    private Integer memAge;
    // 无参构造函数
    // 全参构造函数
    // getter setter toString

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="
        http://www.springframework.org/schema/util
        http://www.springframework.org/schema/util/spring-util.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="family" class="com.giser.spring6.iocref.Family">
        <property name="familyName" value="一家人" />
        <!--
            引用集合类型的bean
        -->
        <property name="memMap" ref="memMap" />
        <property name="memList" ref="memList" />
    </bean>

    <util:list id="memList">
        <ref bean="mem1" />
        <ref bean="mem2" />
        <ref bean="mem3" />
    </util:list>

    <util:map id="memMap">
        <entry>
            <key>
                <value>1001</value>
            </key>
            <ref bean="mem1"/>
        </entry>
        <entry>
            <key>
                <value>1002</value>
            </key>
            <ref bean="mem2"/>
        </entry>
    </util:map>

    <bean id="mem1" class="com.giser.spring6.iocref.Mem">
        <property name="memAge" value="11" />
        <property name="memName" value="小李" />
    </bean>
    <bean id="mem2" class="com.giser.spring6.iocref.Mem">
        <property name="memAge" value="22" />
        <property name="memName" value="小张"/>
    </bean>
    <bean id="mem3" class="com.giser.spring6.iocref.Mem">
        <property name="memAge" value="33" />
        <property name="memName" value="小王"/>
    </bean>
</beans>

3.11 DI之通过p标签为属性赋值

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:util="http://www.springframework.org/schema/util"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="
        http://www.springframework.org/schema/util
        http://www.springframework.org/schema/util/spring-util.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--
        p标签使用
    -->
    <bean id="family" class="com.giser.spring6.iocref.Family"
        p:familyName="一家人"
          p:memMap-ref="memMap"
          p:memList-ref="memList"
    >
    </bean>

    <util:list id="memList">
        <ref bean="mem1" />
        <ref bean="mem2" />
        <ref bean="mem3" />
    </util:list>

    <util:map id="memMap">
        <entry>
            <key>
                <value>1001</value>
            </key>
            <ref bean="mem1"/>
        </entry>
        <entry>
            <key>
                <value>1002</value>
            </key>
            <ref bean="mem2"/>
        </entry>
    </util:map>

    <bean id="mem1" class="com.giser.spring6.iocref.Mem">
        <property name="memAge" value="11" />
        <property name="memName" value="小李" />
    </bean>
    <bean id="mem2" class="com.giser.spring6.iocref.Mem">
        <property name="memAge" value="22" />
        <property name="memName" value="小张"/>
    </bean>
    <bean id="mem3" class="com.giser.spring6.iocref.Mem">
        <property name="memAge" value="33" />
        <property name="memName" value="小王"/>
    </bean>
</beans>

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-p-di.xml");
Family family = applicationContext.getBean("family", Family.class);
logger.info("p标签属性赋值：{}", family);

3.12 DI之引入外部属性文件

jdbc.properties

jdbc.user=root
jdbc.password=root
jdbc.url=jdbc:mysql://localhost:3306/db_mybatis?serverTimezone=UTC
jdbc.driver=com.mysql.cj.jdbc.Driver

beans-jdbc.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"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--
        引入外部属性文件
        注意：在使用 context:property-placeholder 元素加载外包配置文件功能前，首先需要在 XML 配置的一级标签 <beans> 中添加 context 相关的约束。
    -->
    <context:property-placeholder location="classpath:jdbc.properties" />

    <bean id="druidDataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url" value="${jdbc.url}"/>
        <property name="password" value="${jdbc.password}" />
        <property name="username" value="${jdbc.user}" />
        <property name="driverClassName" value="${jdbc.driver}" />
    </bean>
</beans>

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-ds.xml");
DruidDataSource druidDataSource = applicationContext.getBean(DruidDataSource.class);
logger.info("数据库对象：{}", druidDataSource);

3.13 bean的作用域

<?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">

    <!--
        创建对象，并设置作用域范围:
        默认为单例singleton，bean在IOC容器中只有一个实例，IOC容器初始化时创建对象；
        可通过scope属性设置为多实例对象[scope为prototype]，bean在IOC容器中可以有多个实例，getBean()时创建对象
    -->
    <bean id="apple" class="com.giser.spring6.scope.Apple" scope="prototype" />

</beans>

public class SpringScopeTest {

    private final Logger logger = LoggerFactory.getLogger(SpringScopeTest.class);

    /**
     * scope=singleton时：
     * [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'apple'
     * [main] INFO spring6.SpringScopeTest - 单例对象：com.giser.spring6.scope.Apple@436390f4
     * [main] INFO spring6.SpringScopeTest - 单例对象：com.giser.spring6.scope.Apple@436390f4
     *
     * scope="prototype"时：
     * [main] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 1 bean definitions from class path resource [beans-scope.xml]
     * [main] INFO spring6.SpringScopeTest - 单例对象：com.giser.spring6.scope.Apple@733037
     * [main] INFO spring6.SpringScopeTest - 单例对象：com.giser.spring6.scope.Apple@7728643a
     *
     * 如果是在WebApplicationContext环境下还会有另外几个作用域（但不常用）
     * request:在一个请求域内有效
     * session:在一个会话范围内有效
     */
    @Test
    public void testScope(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-scope.xml");
        Apple apple = applicationContext.getBean(Apple.class);
        logger.info("单例对象：{}", apple);
        Apple apple2 = applicationContext.getBean(Apple.class);
        logger.info("单例对象：{}", apple2);
    }

}

3.14 bean的生命周期

package com.giser.spring6.lifecycle;

/**
 * @author giserDev
 * @description
 * @date 2023-12-31 21:22:01
 */
public class Phone {

    private String phoneName;

    public Phone() {
        System.out.println("Bean生命周期：[1 bean对象创建（调用无参构造方法）]");
    }

    public void initMethod(){
        System.out.println("Bean生命周期：[4 bean对象初始化（调用bean配置时init-method属性指定的初始化方法）] ");
    }

    public void destroyMethod(){
        System.out.println("Bean生命周期：[7 bean对象销毁（调用bean配置时destroy-method属性指定的销毁方法）] ");
    }

    public String getPhoneName() {
        return phoneName;
    }

    public void setPhoneName(String phoneName) {
        System.out.println("Bean生命周期：[2 为对象属性赋值（调用属性set方法）] ");
        this.phoneName = phoneName;
    }
}

package com.giser.spring6.lifecycle;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;

/**
 * @author giserDev
 * @description
 * @date 2023-12-31 21:26:40
 */
public class MyBeanProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("Bean生命周期：[3 bean后置处理器（在bean初始化之前执行）] ");
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("Bean生命周期：[5 bean后置处理器（在bean初始化之后执行）] ");
        return bean;
    }

}

<?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">

    <!--
        init-method: 设置对象初始化方法
        destroy-method: 设置对象销毁方法
        scope: 设置对象作用域
    -->
    <bean id="phone" class="com.giser.spring6.lifecycle.Phone"
          init-method="initMethod"
          destroy-method="destroyMethod"
          scope="singleton" >
        <property name="phoneName" value="小米手机" />
    </bean>

    <!-- bean的后置处理器要放入IOC容器才能生效 -->
    <bean id="myBeanProcessor" class="com.giser.spring6.lifecycle.MyBeanProcessor" />

</beans>

import com.giser.spring6.lifecycle.Phone;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @author giserDev
 * @description
 * @date 2023-12-31 21:30:42
 */
public class SpringBeanLifeCycleTest {
    private Logger logger = LoggerFactory.getLogger(SpringBeanLifeCycleTest.class);

    /**
     * 在scope="singleton"情况下：
     * 2023-12-31 22:09:45 404 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@422c3c7a
     * 2023-12-31 22:09:45 631 [main] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [beans-lifecycle.xml]
     * 2023-12-31 22:09:45 679 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'myBeanProcessor'
     * 2023-12-31 22:09:45 713 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'phone'
     * Bean生命周期：[1 bean对象创建（调用无参构造方法）]
     * Bean生命周期：[2 为对象属性赋值（调用属性set方法）]
     * Bean生命周期：[3 bean后置处理器（在bean初始化之前执行）]
     * Bean生命周期：[4 bean对象初始化（调用bean配置时init-method属性指定的初始化方法）]
     * Bean生命周期：[5 bean后置处理器（在bean初始化之后执行）]
     * 2023-12-31 22:09:45 787 [main] INFO spring6.SpringBeanLifeCycleTest - Bean生命周期：[6 bean对象准备就绪，可以使用了]
     * 2023-12-31 22:09:45 789 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Closing org.springframework.context.support.ClassPathXmlApplicationContext@422c3c7a, started on Sun Dec 31 22:09:45 CST 2023
     * Bean生命周期：[7 bean对象销毁（调用bean配置时destroy-method属性指定的销毁方法）]
     * 2023-12-31 22:09:45 793 [main] DEBUG org.springframework.beans.factory.support.DisposableBeanAdapter - Custom destroy method 'destroyMethod' on bean with name 'phone' completed
     */
    @Test
    public void test01(){
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-lifecycle.xml");
        Phone phone = applicationContext.getBean(Phone.class);
        logger.info("Bean生命周期：[6 bean对象准备就绪，可以使用了]");
        applicationContext.close();
    }

}

3.15 FactoryBean

public class UserInfo {
}

public class UserFactoryBean implements FactoryBean<UserInfo> {

    @Override
    public UserInfo getObject() throws Exception {
        return new UserInfo();
    }

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

    @Override
    public boolean isSingleton() {
        return FactoryBean.super.isSingleton();
    }
}

<?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">

    <bean id="userInfo" class="com.giser.spring6.factorybean.UserFactoryBean" />

</beans>

public class SpringFactoryBeanTest {

    private Logger logger = LoggerFactory.getLogger(SpringFactoryBeanTest.class);

    /**
     * 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。
     * 在整合Mybatis时，Spring就是通过FactoryBean机制来帮我们创建SqlSessionFactory对象的。
     *
     * [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@14b030a0
     * [main] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 1 bean definitions from class path resource [beans-factorybean.xml]
     * [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'userInfo'
     * [main] INFO spring6.SpringFactoryBeanTest - 通过FactoryBean获取的对象为com.giser.spring6.factorybean.UserInfo@255990cc
     */
    @Test
    public void testFactoryBean(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-factorybean.xml");
        UserInfo userInfo = applicationContext.getBean(UserInfo.class);
        logger.info("通过FactoryBean获取的对象为{}", userInfo);
    }

}

3.16 自动装配

UserDao

public interface UserDao {
    void sayHello();
}
public class UserDaoImpl implements UserDao {
    @Override
    public void sayHello() {
        System.out.println("userDao sayHello");
    }
}

UserService

public interface UserService {
    void sayHello();
}
public class UserServiceImpl implements UserService {

    private UserDao userDao;

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void sayHello() {
        userDao.sayHello();
    }
}

UserController

public class UserController {

    private UserService userService;

    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    public void sayHello(){
        userService.sayHello();
    }

}

自动装配

<?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">

    <!--
        自动装配：byType 根据类型自动装配bean
    -->
    <!--
    <bean id="userController" class="com.giser.spring6.autowire.controller.UserController" autowire="byType" />
    <bean id="userService" class="com.giser.spring6.autowire.service.impl.UserServiceImpl" autowire="byType" />
    <bean id="userDao" class="com.giser.spring6.autowire.dao.impl.UserDaoImpl" autowire="byType" />
    -->

    <!--
        自动装配：byName 根据名称自动装配bean
    -->
    <bean id="userController" class="com.giser.spring6.autowire.controller.UserController" autowire="byName" />
    <bean id="userService" class="com.giser.spring6.autowire.service.impl.UserServiceImpl" autowire="byName" />
    <bean id="userDao" class="com.giser.spring6.autowire.dao.impl.UserDaoImpl" autowire="byName" />

</beans>

测试

import com.giser.spring6.autowire.controller.UserController;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @author giserDev
 * @description
 * @date 2023-12-31 22:51:15
 */
public class SpringAutowiredTest {

    @Test
    public void testAutowired(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans-autowire.xml");
        UserController userController = applicationContext.getBean(UserController.class);
        userController.sayHello();
    }

}

文章来源:https://blog.csdn.net/SUNBOYmxbsH/article/details/135320584
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