配置bean的4种情况

public interface UserDao {
}
public class UserDaoImpl implements UserDao {
}
public interface UserService {
    void normalMethod();
}
public class UserServiceImpl implements UserService, InitializingBean, DisposableBean {
    private UserDao userDao;
    public UserServiceImpl() {
        System.out.println("执行UserServiceImpl无参构造方法");
    }
    public UserServiceImpl(String name) {
        System.out.println("执行UserServiceImpl有参构造方法, name = " + name);
    }
    public void setUserDao(UserDao userDao) {
        System.out.println("自动依赖注入，设置UserDao");
        this.userDao = userDao;
    }
    @Override
    public void afterPropertiesSet() {
        System.out.println("执行InitializingBean的afterPropertiesSet");
    }
    public void init() {
        System.out.println("执行bean标签定义的初始化方法");
    }
    @Override
    public void normalMethod() {
        System.out.println("执行普通业务方法");
    }
    @Override
    public void destroy() {
        System.out.println("执行DisposableBean的destroy");
    }
    public void myDestroy() {
        System.out.println("执行bean标签定义的销毁方法");
    }
}

UserDao userDao = new UserDaoImpl();

<bean id="userDao" class="com.yt.dao.impl.UserDaoImpl"/>

public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        UserDao userDao = (UserDao) context.getBean("userDao");
        System.out.println(userDao);
        // 输出 com.yt.dao.impl.UserDaoImpl@103f852
    }

UserService userService = new UserServiceImpl("yt");

<bean id="userService"  class="com.yt.service.impl.UserServiceImpl">
        <constructor-arg name="name" value="yt"/>
</bean>

public static void main(String[] args) {
       ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        System.out.println(context.getBean("userService"));
        // 输出
        // 执行UserServiceImpl有参构造方法, name = yt
        // com.yt.service.impl.UserServiceImpl@179bb86
    }

<bean id="userService" class="com.yt.service.impl.UserServiceImpl">
        <constructor-arg name="name" value="yt"/>
        <property name="userDao" ref="userDao"/>
    </bean>
    <bean id="userDao" class="com.yt.dao.impl.UserDaoImpl"/>

public static void main(String[] args) {
       ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        System.out.println(context.getBean("userService"));
        // 输出
        // 执行UserServiceImpl有参构造方法, name = yt
        // 自动依赖注入，设置UserDao
        // com.yt.service.impl.UserServiceImpl@179bb86
    }

<bean id="userService"
          name="aaa,bbb,ccc" // 别名，可起多个，getBean时可使用别名获取
          class="com.yt.service.impl.UserServiceImpl"
          scope="prototype" // 默认单例singleton，非默认原型prototype，即每次获取bean都是不同的实例
          lazy-init="true" //懒加载，只在获取bean时生成bean，默认非懒加载，启动容器就创建bean
          init-method="init" // 指定类里面的一个方法为初始化方法
          destroy-method="myDestroy"> // 指定类里面的一个方法为销毁方法，需要手动关闭容器才可看到执行
    </bean>

public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        System.out.println(context.getBean("userService"));
        userService.normalMethod();
        //当scope是prototype的时候，对象的生存周期spring就不管了。只有在tomcat或者容器关闭的时候，由tomcat调用
        context.close();
    }
// 输出
// 执行UserServiceImpl无参构造方法
// 执行InitializingBean的afterPropertiesSet
// 执行bean标签定义的初始化方法
// com.yt.service.impl.UserServiceImpl@179bb86
// 执行普通业务方法

<bean id="userService1" class="com.yt.factory.MyBeanFactory1" factory-method="getUserService"/>

<bean id="myBeanFactory2" class="com.yt.factory.MyBeanFactory2"/>
    <bean id="userService2" factory-bean="myBeanFactory2" factory-method="getUserService" lazy-init="true"/>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/bai"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.3.23</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.23</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>

<!--配置数据源-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/bai"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>
    <!--配置Connection-->
    <bean id="clazz" class="java.lang.Class" factory-method="forName">
        <constructor-arg name="className" value="com.mysql.jdbc.Driver"/>
    </bean>
    <bean id="connection" class="java.sql.DriverManager" factory-method="getConnection" scope="prototype">
        <constructor-arg name="url" value="jdbc:mysql://localhost:3306/bai"/>
        <constructor-arg name="user" value="root"/>
        <constructor-arg name="password" value="123456"/>
    </bean>
    <!--配置一个当前时间-->
    <bean id="now" class="java.time.LocalDateTime" factory-method="now"/>
    <bean id="dateTimeFormatter" class="java.time.format.DateTimeFormatter" factory-method="ofPattern">
        <constructor-arg name="pattern" value="yyyy-MM-dd HH:mm:ss"/>
    </bean>
    <bean id="nowString" factory-bean="now" factory-method="format">
        <constructor-arg name="formatter" ref="dateTimeFormatter"/>
    </bean>
    <!--配置一个SqlSessionFactory-->
    <bean id="mybatisConfigInputStream" class="org.apache.ibatis.io.Resources" factory-method="getResourceAsStream">
        <constructor-arg name="resource" value="mybatis-config.xml"/>
    </bean>
    <bean id="sqlSessionFactoryBuild" class="org.apache.ibatis.session.SqlSessionFactoryBuilder"/>
    <bean id="sqlSessionFactory" factory-bean="sqlSessionFactoryBuild" factory-method="build">
        <constructor-arg name="inputStream" ref="mybatisConfigInputStream"/>
    </bean>

public class ThirdPartyBeanTest {
    public static void main(String[] args) throws Exception {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        System.out.println(context.getBean("dataSource"));
        System.out.println(context.getBean("connection"));
        System.out.println(context.getBean("connection"));
        System.out.println(context.getBean("nowString"));
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = builder.build(is);
        System.out.println(sqlSessionFactory);
        System.out.println(context.getBean("sqlSessionFactory"));
    }
}
// 输出
{
  CreateTime:"2022-11-10 23:53:05",
  ActiveCount:0,
  PoolingCount:0,
  CreateCount:0,
  DestroyCount:0,
  CloseCount:0,
  ConnectCount:0,
  Connections:[
  ]
}
Thu Nov 10 23:53:05 CST 2022 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
com.mysql.jdbc.JDBC4Connection@1af006c
Thu Nov 10 23:53:07 CST 2022 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
com.mysql.jdbc.JDBC4Connection@1d1433e
2022-11-10 23:53:05
org.apache.ibatis.session.defaults.DefaultSqlSessionFactory@46293d
org.apache.ibatis.session.defaults.DefaultSqlSessionFactory@1997e9d
Process finished with exit code 0