spring整合mybatis详解

﹏ヽ暗。殇╰゛Y 2024-04-02 03:32 81阅读 0赞

#### 文章目录 ####

*  前言
 *  一、实现步骤
 *  二、使用mybatis-config.xml
 *  出现的BUG

--------------------

## 前言 ##

本篇主要讲怎么使用spring整合mybatis

--------------------

## 一、实现步骤 ##

> spring的特点是IOC和AOP，IOC是控制反转，即创建对象。整合spring和mybatis正是使用了spring的这种特点。我们可以使用spring创建如下对象，来整和mybatis。

*  数据库的连接对象
 *  创建SqlSessionFactory
 *  创建SqlSession对象
 *  获得Mapper的代理对象

实现步骤:

*  准备数据酷
 *  创建java-maven项目
 *  导入依赖
    
     *  spring
     *  mybatis
     *  数据库驱动
     *  spring整合mybatis的单独依赖
     *  spring-jdbc,对Dao层的支持
 *  配置文件
    
     *  applicationContext.xml \[重点\]
        
         *  加载数据配置文件
         *  配置数据源
         *  创建SqlSessionFactory
         *  配置Mapper扫描器
     *  mybatis-config.xml
     *  db.properties
     *  log4j.properties
 *  类文件
    
     *  User
     *  UserService
     *  UserServiceImpl
     *  UserMapper.java
     *  UserMapper.xml
 *  测试

> 创建maven，数据库和实体类、前几篇已经记录过不在进行一一演示。

在maven的基础上导入依赖

<dependencies>
       	    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>5.1.6.RELEASE</version>
            </dependency>
    		
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-aspects</artifactId>
                <version>5.1.6.RELEASE</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-jdbc</artifactId>
                <version>5.1.6.RELEASE</version>
            </dependency>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.7</version>
            </dependency>
    	    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.47</version>
            </dependency>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis-spring</artifactId>
                <version>1.3.1</version>
            </dependency>
    		
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.17</version>
            </dependency>
        </dependencies>
    
        <build>
            <resources>
                <resource>
                    <directory>src/main/java</directory>
                    <includes>
                        <include>*.xml</include>
                        <include>**/*.xml</include>
                    </includes>
                    <filtering>true</filtering>
                </resource>
            </resources>
        </build>

> 编写配置文件applicationContext.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/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    
        
        <context:component-scan base-package="com.lzl"/>
    
        
        <context:property-placeholder location="classpath:db.properties"/>
    
        
        <bean id="dataSource" class="org.apache.ibatis.datasource.pooled.PooledDataSource">
            <property name="driver" value="${jdbc.driver}"/>
            <property name="url" value="${jdbc.url}"/>
            <property name="username" value="${jdbc.username}"/>
            <property name="password" value="${jdbc.password}"/>
        </bean>
    
    
        
        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            
            <property name="dataSource" ref="dataSource"/>
    
            
            <property name="typeAliasesPackage" value="com.lzl.model"/>
    
        </bean>
    
        
        <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
            <property name="basePackage" value="com.lzl.mapper"/>
            <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        </bean>
    </beans>

> 编写mybatis-config.xml配置

<?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>
        
    </configuration>

> db.properties 数据源配置

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/库名?useSSL=false
    jdbc.username=用户名
    jdbc.password=密码

> log4j.properties日志配置

log4j.rootLogger=error
    log4j.logger.com.qf.mapper=debug,stdout
    
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

> 服务层的实现

public interface UserService {
        
        User findUserById(int id);
    }
    
    @Service
    public class UserServiceImpl implements UserService {
        
    
        // 设置Dao属性
        @Autowired // 自动注入Mapper
        private UserMapper userMapper;
    
        @Override
        public User findUserById(int id) {
        
            User user = userMapper.findUserById(id);
            return user;
        }
    }

> 持久层的实现

public interface UserMapper {
        
        User findUserById(int id);
    }

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.qf.mapper.UserMapper">
    
        <select id="findUserById" parameterType="int" resultType="User">
            select * from user where id = #{id}
        </select>
    
    </mapper>

> 测试类编写

public class TestSpringMybatis {
        
    
        public static void main(String[] args) {
        
            ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
            UserService service = context.getBean("userServiceImpl", UserService.class);
    
            User user = service.findUserById(51);
            System.out.println(user);
        }
    }

> 至此已经将spring和mybatis整合完毕

## 二、使用mybatis-config.xml ##

上述整合步骤中，将所有的mybatis配置文件中的内容全部整合到了applicationContext.xml中。我们还可以使用另外一种方式来进行整和  
这里仅作一种配置别名使用mybatis-config.xml演示

<configuration>
        
        
        <typeAliases>
            <package name="com.qf.model"/>
        </typeAliases>
        
    </configuration>

在applicationContext.xml中加载该配置

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            
            <property name="configLocation" value="classpath:mybatis-config.xml"/>
    
            
            <property name="dataSource" ref="dataSource"/>
    
            
            
        </bean>

--------------------

## 出现的BUG ##

整合完毕以后，log4j日志不显示。原因在于整合mybatis后,mybatis自己无法确定到底使用哪一个日志框架.所以,需要在mybatis的全局配置文件中,指定日志的实现方案为log4j。