Spring学习笔记

Spring学习笔记02

一、使用JAVA代码的方式配置Spring

1.pojo包的同目录下创建一个名为config的包，config包中存放配置类java代码

package com.hx.config;

import com.hx.pojo.User;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

//@Configuration代表这是一个配置类和beans.xml一样
@Configuration
@ComponentScan("com.hx.pojo")//扫描到类
@Import(HxConfig2.class)
public class HxConfig {

    //@Bean：注册一个bean相当于xml文件里面的一个bean标签
    //方法名相当于bean标签中id的属性
    //方法的返回值相当于bean标签中class属性
    @Bean
    public User getUser(){
        return new User();
    }//返回到要注入的bean对象
}

二、Spirng整合Mybatis

1.导入依赖

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.4</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
    </dependencies>

以上为Spring整合Mybatis时必需的依赖，为了防止IDEA访问不到资源文件还需要加上配置

    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

2.编写配置文件spring-dao.xml配置好数据源、sqlSessionFactory以及SqlSessionTemplate

<?xml version="1.0" encoding="UTF8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-3.0.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <!--DataSource:使用Spring的数据源替换Mybatis的配置-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/day1118?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=GMT%2B8"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>

    <!--sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!--绑定Mybatis配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <property name="mapperLocations" value="classpath:com/hx/mapper/*.xml"/>
    </bean>

    <!--SqlSessionTemplate就是mybatis中的SqlSession-->
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--只能用构造器注入sqlSessionFactory因为其不具有set方法-->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>


    <bean id="userMapper" class="com.hx.mapper.UserMapperImpl">
        <property name="sqlSession" ref="sqlSession"/>
    </bean>
</beans>

3.编写好接口并在mapper.xml文件中配置好SQL语句

package com.hx.mapper;

import com.hx.pojo.User;

import java.util.List;

public interface UserMapper {
    public List<User> selectUser();
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hx.mapper.UserMapper">
    <select id="selectUser" resultType="user">
        select * from user
    </select>
</mapper>

4.编写好接口的实现类并注入到Spring中

package com.hx.mapper;

import com.hx.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;

import java.util.List;

public class UserMapperImpl implements UserMapper {

    //现在所有的操作都使用SqlSessionTemplate来执行了（以前是使用sqlSession）
    private SqlSessionTemplate sqlSession;

    public void setSqlSession(SqlSessionTemplate sqlSession){
        this.sqlSession = sqlSession;
    }
    public List<User> selectUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}

编写一个applicationContext.xml配置文件专门用来注册bean，并将spring-dao.xml配置文件导入

<?xml version="1.0" encoding="UTF8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-3.0.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <import resource="spring-dao.xml"/>


    <bean id="userMapper" class="com.hx.mapper.UserMapperImpl">
        <property name="sqlSession" ref="sqlSession"/>
    </bean>

</beans>

5.测试成功之后就可以使用了

三、声明式事务

声明式事务是通过AOP实现的，不同于编程式事务的是，只需要在配置文件中配置好声明式事务就可以管理事务，而不用在代码中进行事务的管理了

1.事务ACID原则：

事务具有原子性、一致性、隔离性、持久性的特点，在工作中可能会有多个业务操作同一个资源的情况，为了防止数据的损坏或者不一致需要重视事务的管理

2.声明式事务的配置：见具体代码

<?xml version="1.0" encoding="UTF8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-3.0.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <!--DataSource:使用Spring的数据源替换Mybatis的配置-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/day1118?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=GMT%2B8"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>

    <!--sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!--绑定Mybatis配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <property name="mapperLocations" value="classpath:com/hx/mapper/*.xml"/>
    </bean>

    <!--SqlSessionTemplate就是mybatis中的SqlSession-->
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--只能用构造器注入sqlSessionFactory因为其不具有set方法-->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>

    <!--配置声明式事务-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--结合AOP实现事务的织入-->
    <!--配置事务通知-->
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <!--给哪些方法配置事务-->
        <!--配置事务的传播特性-->
        <tx:attributes>
            <tx:method name="add" propagation="REQUIRED"/>
            <tx:method name="delete" propagation="REQUIRED"/>
            <tx:method name="update" propagation="REQUIRED"/>
            <tx:method name="query" read-only="true"/>
            <tx:method name="*" propagation="REQUIRED"/>
        </tx:attributes>
    </tx:advice>

    <!--配置事务切入-->
    <aop:config>
        <aop:pointcut id="txPointCut" expression="execution(* com.hx.mapper.*.*(..))"/>
        <aop:advisor advice-ref="txAdvice" pointcut-ref="txPointCut"/>
    </aop:config>

</beans>

注：该博客只作为自己的学习笔记使用，写的不够详细

四、总结

学习过程中遇到的错误

1.异常com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: 2 字节的 UTF-8 序列的字节 2 无效。

原因：这个问题的主要原因是xml文件中声明的编码与xml文件本身保存时的编码不一致。
解决办法：重新设置xml文件保存时的编码与声明的一致

<?xml version="1.0" encoding="UTF-8"?>

改为

<?xml version="1.0" encoding="UTF8"?>

2.控制台报错Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.

原因：这个错误一般是xml文件与实体类的映射错误
解决办法：仔细查找xml文件中的可能出现错误的地方逐个排查