Spring筆記(四)整合Mybatis

今天一定發表於2020-11-30
Spring筆記MyBatis

整合Mybatis

一、mybatis回憶?

maven庫?

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>spring-study</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>spring-10-mybatis</artifactId>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <!--Spring運算元據庫的話，還需要個spring-jdbc-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.13</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>

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

1. 編寫實體類

package com.spring.pojo;

import lombok.Data;

/**
 * @Author: qsX
 * @Time: 2020-11-29 22:26
 * @Description:實體類
 */
@Data
public class User {
    private int id;
    private String name;
    private String pwd;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

2. 編寫核心配置檔案

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <typeAliases>
        <package name="com.spring.pojo"/>
    </typeAliases>

    <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/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
    	<!--注意這裡是class還是resource-->
        <mapper class="com.spring.Mapper.UserMapper"/>
    </mappers>

</configuration>

3. 編寫介面

package com.spring.Mapper;

import com.spring.pojo.User;

import java.util.List;

/**
 * @Author: qsX
 * @Time: 2020-11-29 22:36
 * @Description:介面
 */
public interface UserMapper {
    public List<User> selectUser();
}

4. 編寫Mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.spring.Mapper.UserMapper">

    <select id="selectUser" resultType="user">
        select * from mybatis.user;
    </select>

</mapper>

5. 測試

import com.spring.Mapper.UserMapper;
import com.spring.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;


import java.io.IOException;
import java.io.InputStream;
import java.util.List;

/**
 * @Author: qsX
 * @Time: 2020-11-29 22:52
 * @Description:測試
 */
public class MyTest {
    @Test
    public void test() throws IOException {
        
        String resources = "mybatis-config.xml";
        InputStream in = Resources.getResourceAsStream(resources);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
        SqlSession session = sqlSessionFactory.openSession(true);


        UserMapper mapper = session.getMapper(UserMapper.class);
        List<User> users = mapper.selectUser();

        for (User u : users) {
            System.out.println(u.toString());
        }
    }
}

注意：

  • 遇到找不到mapper.xml之類報錯，可以試試在pom中新增引入語句
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

二、mybaits-spring

mybaits-spring介紹：http://mybatis.org/spring/zh/index.html

0. 匯入相關JAR包

- junit
- mybatis
- mysql
- spring相關的
- aop植入
- mybatis-spring（新知識點）

1. 編寫資料來源配置

  • sqlSessionFactory
  • sqlSessionTemplate
  • spring-dao.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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--dataSource:使用spring的資料來源替換Mybatis的配置，c3p0，dbpc，druid-->
    <!--這裡使用spring提供的JDBC：org.springframework.jdbc.datasource-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>

    <!--sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <!--繫結mybatis配置檔案（附加點，非必要）-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <property name="mapperLocations" value="classpath:com/spring/Mapper/*.xml"/>
    </bean>

    <!--sqlSessionTemplate:就是我們使用的sqlSession-->
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--只能使用構造器注入，因為其沒有set方法-->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>

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

</beans>
  • mybatis-config.xml?多數移到spring-dao.xml中
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!--別名管理-->
    <typeAliases>
        <package name="com.spring.pojo"/>
    </typeAliases>

    <!--設定-->
<!--    <settings>
        <setting name="" value=""/>
    </settings>-->


    <!--換到spring-dao.xml中-->
<!--    <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/test"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>-->


    <!--換到spring-dao.xml中-->
<!--    <mappers>
        &lt;!&ndash;注意這裡是class還是resource&ndash;&gt;
        <mapper class="com.spring.Mapper.UserMapper"/>
    </mappers>-->

</configuration>

2. 需要給介面加實現類

  • 實現類?
package com.spring.Mapper;

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

import java.util.List;

/**
 * @Author: qsX
 * @Time: 2020-11-30 01:37
 * @Description:實現類
 */
public class UserMapperImpl implements UserMapper{

    /*原來都是用sqlSession來執行操作，
    * 現在改為使用sqlSessionTemplate*/

    private SqlSessionTemplate sqlSession;


    public void setSqlSession(SqlSessionTemplate sqlSession) {
        this.sqlSession = sqlSession;
    }

    @Override
    public List<User> selectUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}

3. 將自己寫的實現類注入到Spring中,（這裡可單獨寫個配置檔案放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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

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

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

</beans>

4. 測試使用即可

    @Test
    public void test2() throws IOException {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
        UserMapper userMapper = context.getBean("userMapper",UserMapper.class);
        for (User user : userMapper.selectUser()) {
            System.out.println(user.toString());
        }
    }

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