Spring入门

于 2023-04-01 00:00:00 发布
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Spring入门

引入依赖

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.3.23</version>
</dependency>

结构：

在这里插入图片描述

创建UserService及UserServiceImpl
public interface UserService {}

import com.hngc.spring.dao.UserDao;
import com.hngc.spring.service.UserService;

public class UserServiceImpl implements UserService {
    private UserDao userDao;

    /**
     * BeanFactory自动调用该方法，将容器内userDao设置到此处
     *
     * @param userDao userDao
     */
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}
创建UserDao及UserDaoImpl
public interface UserDao {}

import com.hngc.spring.dao.UserDao;

public class UserDaoImpl implements UserDao {
}
Spring配置文件

在这里插入图片描述

<?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">
    <!--    配置userService-->
    <bean id="userService" class="com.hngc.spring.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"></property>
    </bean>
    <!--    配置userMapper-->
    <bean id="userDao" class="com.hngc.spring.dao.impl.UserDaoImpl"></bean>
</beans>

BeanFactory方式

测试类
import com.hngc.spring.service.UserService;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;

public class SpringDemo {
    public static void main(String[] args) {
        //创建BeanFactory
        DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
        //创建读取器
        XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
        //加载配置文件
        reader.loadBeanDefinitions("beans.xml");
        //获取Bean实例对象
        UserService bean = (UserService) beanFactory.getBean("userService");
        System.out.println(bean);
    }
}

运行结果：

com.hngc.spring.service.impl.UserServiceImpl@3590fc5b

ApplicationContext方式（推荐）

ApplicationContext是BeanFactory的子类，并融合了其他扩展，功能也更加强大

在这里插入图片描述

配置文件

放在 resources 目录下，配置文件名称自定义，一般规范命名为applicationContext.xml，内容和之前BeanFactory一样

<?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">
    <!--    配置userService-->
    <bean id="userService" class="com.hngc.spring.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"></property>
    </bean>
    <!--    配置userMapper-->
    <bean id="userDao" class="com.hngc.spring.dao.impl.UserDaoImpl"></bean>
</beans>
测试类：
import com.hngc.spring.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class ApplicationContextDemo {
    public static void main(String[] args) {
        //加载配置文件
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取Bean实例对象
        UserService userService = (UserService) applicationContext.getBean("userService");
        System.out.println(userService);
    }
}

运行输出：

com.hngc.spring.service.impl.UserServiceImpl@6a370f4

构造方法实例化Bean

默认情况下会调用UserServiceImpl无参构造实例化

若想要调用有参构造实例化Bean需提供有参构造并在配置文件添加constructor-arg标签传递参数

    <!--    配置userService-->
    <bean id="userService" class="com.hngc.spring.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"></property>
        <constructor-arg name="username" value="test"></constructor-arg>
    </bean>
    <!--    配置userMapper-->
    <bean id="userDao" class="com.hngc.spring.dao.impl.UserDaoImpl"></bean>

import com.hngc.spring.dao.UserDao;
import com.hngc.spring.service.UserService;

public class UserServiceImpl implements UserService {
    private UserDao userDao;

    public UserServiceImpl() {
        System.out.println("调用无参构造...");
    }
    public UserServiceImpl(String username) {
        System.out.println("调用参构造...");
    }
    /**
     * BeanFactory调用该方法，将容器内userDao设置到此处
     *
     * @param userDao userDao
     */
    @Override
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

工厂实例化Bean

静态工厂实例化Bean
import com.hngc.spring.dao.UserDao;
import com.hngc.spring.dao.impl.UserDaoImpl;

public class MyFactoryBean {

    /**
     * 静态工厂	可在实例化之前z做一些业务操作
     * @param username
     * @return
     */
    public static UserDao userDao(String username) {
        return new UserDaoImpl();
    }

}

配置文件

<!--    调用静态方法实例化-->
<bean id="userDao1" class="com.hngc.spring.factory.MyFactoryBean" factory-method="userDao">
    <constructor-arg name="username" value="test"></constructor-arg>
</bean>
实例工厂实例化Bean
<!--配置工厂对象-->
<bean id="myFactoryBean2" class="com.hngc.spring.factory.MyFactoryBean2"></bean>
<!--实例化Bean-->
<bean id="userDao2" factory-bean="myFactoryBean2" factory-method="userDao"></bean>

import com.hngc.spring.dao.UserDao;
import com.hngc.spring.dao.impl.UserDaoImpl;

public class MyFactoryBean2 {

    public UserDao userDao() {
        return new UserDaoImpl();
    }
}
实现BeanFactory延迟加载实例化Bean

懒加载

import com.hngc.spring.dao.UserDao;
import com.hngc.spring.dao.impl.UserDaoImpl;
import org.springframework.beans.factory.FactoryBean;

public class MyFactoryBean3 implements FactoryBean<UserDao> {

    /**
     * 
     * @return 返回的Bean
     * @throws Exception
     */
    @Override
    public UserDao getObject() throws Exception {
        return new UserDaoImpl();
    }

    /**
     * 
     * @return 返回Bean的类型
     */
    @Override
    public Class<?> getObjectType() {
        return UserDao.class;
    }
}

配置文件

<bean id="userDao3" class="com.hngc.spring.factory.MyFactoryBean3"></bean>

Bean依赖注入配置

其中，ref是 reference的缩写形式，翻译为:涉及，参考的意思，用于引用其他Bean的id。value用于注入普通属性值。

注入方式配置方式
通过Bean的set方法注入<property name="userDao" ref="userDao"></property> <property name="userDao" ref="userDao"></property>
通过构造bean1方法进行注入<constructor-arg name="username" value="userDao"></constructor-arg>``<constructor-arg name="username" value="userDao"></constructor-arg>
注入List集合属性

示例

    private List<String> stringList;

    public void setStringList(List<String> stringList) {
        this.stringList = stringList;
    }

配置

属性为普通类型

<bean id="userService1" class="com.hngc.spring.service.impl.UserServiceImpl">
    <property name="stringList">
        <list>
            <value>aaa</value>
            <value>bbb</value>
            <value>ccc</value>
        </list>
    </property>
</bean>

属性为bean类型

private List<UserDao> userDaoList;

public void setUserDaoList(List<UserDao> userDaoList) {
    this.userDaoList = userDaoList;
}

<bean id="userService1" class="com.hngc.spring.service.impl.UserServiceImpl">
    <property name="userDaoList">
        <list>
            <bean id="userDao1" factory-bean="myFactoryBean2" factory-method="userDao"></bean>
            <bean id="userDao2" factory-bean="myFactoryBean2" factory-method="userDao"></bean>
            <bean id="userDao3" factory-bean="myFactoryBean2" factory-method="userDao"></bean>
        </list>
    </property>
</bean>
注入Set集合属性

示例

    private Set<String> stringSet;

    public void setStringSet(Set<String> stringSet) {
        this.stringSet = stringSet;
    }

配置

属性为普通类型

<bean id="userService1" class="com.hngc.spring.service.impl.UserServiceImpl">
    <property name="stringSet">
        <set>
            <value>aaa</value>
            <value>bbb</value>
            <value>ccc</value>
        </set>
    </property>
</bean>

属性为bean类型

private Set<UserDao> userDaoSet;

public void setUserDaoSet(List<UserDao> userDaoSet) {
    this.userDaoSet = userDaoSet;
}

<bean id="userService1" class="com.hngc.spring.service.impl.UserServiceImpl">
    <property name="userDaoSet">
        <set>
            <bean id="userDao1" factory-bean="myFactoryBean2" factory-method="userDao"></bean>
            <bean id="userDao2" factory-bean="myFactoryBean2" factory-method="userDao"></bean>
            <bean id="userDao3" factory-bean="myFactoryBean2" factory-method="userDao"></bean>
        </set>
    </property>
</bean>
注入map集合属性
private Map<String,String> stringMap;

public void setStringMap(Map<String, String> stringMap) {
    this.stringMap = stringMap;
}

<bean id="userService3" class="com.hngc.spring.service.impl.UserServiceImpl">
    <property name="stringMap">
        <map>
            <entry key="username" value="zhangsan"></entry>
            <entry key="age" value="18"></entry>
        </map>
    </property>
</bean>
自动装配

自动装配可选byName和byType(不推荐，因为当有多个类型相同的Bean时会出现错误)

<!--    配置userService-->
<bean id="userService" class="com.hngc.spring.service.impl.UserServiceImpl" autowire="byName"></bean>
<!--    配置userMapper-->
<bean id="userDao" class="com.hngc.spring.dao.impl.UserDaoImpl"></bean>

基于xml的Spring应用

Bean 实例化的基本流程
  • 加载xml配置文件，解析获取配置中的每个的信息，封装成一个个的BeanDefinition对象;
  • 将BeanDefinition存储在一个名为beanDefinitionMap的Map<String,BeanDefinition>中;
  • ApplicationContext底层遍历beanDefinitionMap，创建Bean实例对象;
  • 创建好的Bean实例对象，被存储到一个名为singletonObjects的Map<String,Object>中;
  • 当执行applicationContext.getBean(beanName)时，从singletonObjects去匹配Bean实例返回。

在这里插入图片描述

spring后处理器
Bean生命周期
xml方式整合第三方框架
整合mybatis
Spring整合MyBatis的原理剖析

整合包里提供了一个SqlSessionFactoryBean和一个扫描Mapper的配置对象，SqlSessionFactoryBean一旦被实例化，就开始扫描Mapper并通过动态代理产生Mapper的实现类存储到Sping容器中。相关的有如下四个类：

  • SqlSessionFactoryBean：需要进行配置，用于提供SqlSessionFactory
  • MapperScannerConfig：需要进行配置，用于扫描指定Mapper注册BeanDefinition
  • MapperFactoryBean：Mapper的FactoryBean，获取指定Mapper时调用getObject方法
  • ClassPathMapperScanner：definition.setAutowireMode(2)修改了自动注入状态，所以MapperFactoryBean中的setSqlSessionFactory会自动注入进去

引入依赖：

<!-- mysql-connector-java-->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.30</version>
</dependency>
<!-- mybatis-->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.11</version>
</dependency>
<!-- spring-jdbc-->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.3.21</version>
</dependency>
<!-- mybatis-spring-->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>2.0.6</version>
</dependency>
编写spring配置文件
    <bean id="userService" class="com.hngc.spring.service.impl.UserServiceImpl">
        <property name="userMapper" ref="userMapper"></property>
    </bean>
    <!--    配置数据源信息-->
    <bean id="datasource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis"></property>
        <property name="username" value="Java"></property>
        <property name="password" value="123456"></property>
    </bean>
    <!--    配置sqlSessionFactoryBean,作用：将sqlSessionFactoryBean初始化到容器-->
    <bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="datasource"></property>
    </bean>

    <!--    配置mapperScannerConfigurer,作用：扫描指定的包，产生mapper对象存储到spring容器-->
    <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.hngc.spring.mapper"></property>
    </bean>

<bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="datasource"></property>
</bean>

<!--    配置mapperScannerConfigurer,作用：扫描指定的包，产生mapper对象存储到spring容器-->
<bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.hngc.spring.mapper"></property>
</bean>
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