Spring整合Mybatis淺嘗

時間  2019-11-29
標籤 spring 整合 mybatis 淺嘗 欄目 Spring 简体版
原文   原文鏈接

　　初學，記錄本身學習整合兩個框架的過程，裏面也有不少踩過的坑，也有沒有解決的問題，先記錄下來。等待解決。java

廢話很少說，直接開始了。先上pom.xml配置文件。mysql

This is my pom.xml

<?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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>Sping_Mybatis</groupId>
    <artifactId>spring_mybatis_test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
            <scope>test</scope>
        </dependency>
        <dependency><!-- spring對測試框架的簡單封裝功能 -->
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>4.2.0.RELEASE</version>
            <scope>test</scope>
        </dependency>

        <!-- 數據源 -->
        <dependency>
            <groupId>commons-dbcp</groupId>
            <artifactId>commons-dbcp</artifactId>
            <version>1.4</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.0.8</version>
        </dependency>

        <!-- Mybatis3.4.1 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>

        <!-- spring整合mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.3.0</version>
        </dependency>

        <!-- Spring-4.2.0 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>4.2.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>4.2.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>4.2.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.8</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

    </dependencies>

</project>

　　貼上一張項目目錄的圖git

再來看mybatisConfig.xml的配置web

　　數據源在spring的配置文件裏，同時spring文件裏配置了自動掃描Mapper。故在此不用再次編寫<mappers>中的內容spring

<?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>
    <settings>
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <typeAliases>
        <typeAlias type="com.lpp.test.entity.Car" alias="car"/>
    </typeAliases>
    <!--<mappers>
        <mapper url="config/sqlMapper/CarMapper.xml"/>
    </mappers>-->
</configuration>

　　此時再來看spring_mybatis.xml的配置，在這裏面有個問題暫時還未解決。把jdbc.properties放在resource目錄下以後，在spring配置中引入失敗。在配置數據源時候，變量失效，暫時沒有解決是什麼問題，先放在這裏吧。等待之後回過頭解決。配置的很簡單。解決方法在一篇博客中找到了，具體緣由和解決方案放在最下邊。sql

<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       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.lpp.test"/>
    <!--<context:property-placeholder location="classpath:jdbc.properties"/>

    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:jdbc.properties" />
    </bean>-->
    <!--配置數據源-->
    <bean id="dataSource"
          class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"
          p:driverClassName="com.mysql.jdbc.Driver"
          p:url="jdbc:mysql://localhost:3306/test"
          p:username="root"
          p:password=""
    /><!--${driverClasss}${jdbcUrl}${username}com.mysql.jdbc.Driver-->

    <bean id="sqlSessionFactory"
          class="org.mybatis.spring.SqlSessionFactoryBean"
          p:dataSource-ref="dataSource"
          p:configLocation="classpath:config/mybatisConfig.xml"
          p:mapperLocations="classpath:config/sqlMapper/*.xml"/>
    <!--這裏使用spring提供的SQLSessionTemplate-->
    <bean class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg ref="sqlSessionFactory"/>
    </bean>

    <!-- 掃描直接使用mapper接口類操做dao，並直接歸入IOC容器管理 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"
          p:sqlSessionFactory-ref="sqlSessionFactory"
          p:basePackage="com.lpp.test.dao">
    </bean>
</beans>

　　接下來是Mapper.xml的配置，三種配置效果差很少是同樣的，寫法上不太相同，跟carMapper接口對比來看就知道是三種方式。express

<?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.lpp.test.dao.carMapper">
    <select id="findCarbyId" parameterType="int" resultType="Car">
        SELECT id,car_name AS carName,maxSpeed FROM t_car WHERE id = #{id}
    </select>
    <select id="findCarbyIdAndName" resultType="Car">
        SELECT * FROM t_car WHERE id = #{id} AND car_name = #{car_name};
    </select>
    <select id="findCarbyIdAndSpeed" resultType="Car">
        SELECT * FROM t_car WHERE id = #{id} AND maxSpeed = #{maxSpeed};
    </select>
</mapper>

　　carMapper接口apache

package com.lpp.test.dao;

import com.lpp.test.entity.Car;
import org.apache.ibatis.annotations.Param;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: lpp
 * Date: 2018-04-17
 * Time: 19:44
 */
public interface carMapper {
    public Car findCarbyId(int id);
    public Car findCarbyIdAndName(@Param("id") int id, @Param("car_name") String car_name);
    public Car findCarbyIdAndSpeed(Car car);
}

　　

　　貼上log4j.properties的配置session

# Global logging configuration\uff0c\u5efa\u8bae\u5f00\u53d1\u73af\u5883\u4e2d\u8981\u7528debug
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

　　entity下的實體 car.javamybatis

package com.lpp.test.entity;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: lpp
 * Date: 2018-04-16
 * Time: 11:06
 */
public class Car {
    int id;
    String carName;
    int maxSpeed;

    public Car() {
    }

    public Car(int id, String carName, int maxSpeed) {
        this.id = id;
        this.carName = carName;
        this.maxSpeed = maxSpeed;
    }

    public int getId() {
        return id;
    }


    public String getCarName() {
        return carName;
    }

    public int getMaxSpeed() {
        return maxSpeed;
    }

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

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

    public void setMaxSpeed(int maxSpeed) {
        this.maxSpeed = maxSpeed;
    }

    @Override
    public String toString() {
        return "Car{" +
                "id=" + id +
                ", name='" + carName + '\'' +
                ", maxSpeed=" + maxSpeed +
                '}';
    }
}

　　最後是測試方法，我建立了一個測試方法和一個主方法測試，代碼分別以下。

test方法

package com.lpp.test.dao;

import com.lpp.test.entity.Car;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import static org.junit.Assert.*;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: lpp
 * Date: 2018-04-27
 * Time: 17:36
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:config/spring-mybatis.xml")
public class carMapperTest {
    @Autowired
    carMapper carMapper;
    @Test
    public void findCarbyIdAndName() {
        Car car = carMapper.findCarbyIdAndName(1,"aodi");
        System.out.println(car);
    }
}

　　主方法

package com.lpp.test.main;

import com.lpp.test.dao.carMapper;
import com.lpp.test.entity.Car;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: lpp
 * Date: 2018-04-25
 * Time: 17:44
 */
public class testMain {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("config/spring-mybatis.xml");
        carMapper carMapper = ctx.getBean(com.lpp.test.dao.carMapper.class);

        Car car = null;
        car = carMapper.findCarbyId(1);
        System.out.println(car.toString());
    }
}

　　兩種測試方法結果是相同的，調用了不一樣的查詢函數。以上就是我作整合的步驟，初次嘗試，不免有些問題，但願能讓你們收穫一些東西。

　　附：引入jdbc屬性文件以後報錯，Cannot load JDBC driver class ${jdbc.driverClassName}

引發緣由：在spring裏使用org.mybatis.spring.mapper.MapperScannerConfigurer 進行自動掃描的時候，設置了sqlSessionFactory 的話，可能會致使PropertyPlaceholderConfigurer失效，也就是用${jdbc.username}這樣之類的表達式，將沒法獲取到properties文件裏的內容。

　　致使這一緣由是由於，MapperScannerConigurer實際是在解析加載bean定義階段的，這個時候要是設置sqlSessionFactory的話，會致使提早初始化一些類，這個時候，PropertyPlaceholderConfigurer還沒來得及替換定義中的變量，致使把表達式看成字符串複製了。

　　解決思路

1.   若是不設置sqlSessionFactory 屬性的話，就必需要保證sessionFactory在spring中名稱必定要是sqlSessionFactory ，不然就沒法自動注入。

2.   直接定義 MapperFactoryBean

3.   放棄自動代理接口方式。

　　我理解的解決方案：

　　單數據源下刪除下列屬性

<property name="sqlSessionTemplate" value="sqlSessionFactory" />或者default-autowire="byName"

　　多數據源下改用sqlSessionFactoryBeanName。多數據源解決方案暫時不太理解，後續繼續學習

 

 附上gitee地址：https://gitee.com/LL7_s/personal_test_code_sorting/tree/master/spring_mybatis_test

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