4.Spring集成MyBatis

Posted 2021-08-15 小马Mark

集成步骤

1. 创建maven项目
2. 加入maven依赖
   • spring依赖
   • mybatis依赖
   • mysql驱动依赖
   • spring事务依赖
   • mybatis和spring集成依赖（mybatis官方提供的，用来在spring项目中创建mybatis的SqlSessionFactory，dao对象）
3. 创建实体类
4. 创建dao接口和mapper文件
5. 创建mybatis主配置文件
6. 创建Service接口和实现类，属性是dao
7. 创建spring的配置文件：声明mybatis的对象交给spring创建
   • 数据源
   • SQLSessionFactory
   • dao对象
   • 声明自定义的service
8. 创建测试类，获取Service对象，通过service调用dao完成数据库的访问

创建maven项目

略

加入依赖

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <!--spring的核心ioc-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <!--spring做事务用到的依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <!--mybatis依赖-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.1</version>
    </dependency>
    <!--mybatis和spring集成依赖-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>1.3.1</version>
    </dependency>
    <!--mysql数据库驱动依赖-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.9</version>
    </dependency>
    <!--druid连接池依赖-->
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.12</version>
    </dependency>
  </dependencies>

创建实体类

package com.maj.domain;

public class Student {
    private Integer id;
    private String name;
    private Integer age;

    public Student() {
    }

    public Student(Integer id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

创建dao接口和mapper文件

package com.maj.dao;

import com.maj.domain.Student;

import java.util.List;

public interface StudentDao {
    int insertStudent(Student student);

    List<Student> selectStudents();

}

<?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.maj.dao.StudentDao">
    <insert id="insertStudent">
        insert into student values (#{id},#{name},#{age})
    </insert>

    <select id="selectStudents" resultType="com.maj.domain.Student">
        select id,name,age from student order by id desc
    </select>
</mapper>

创建mybatis主配置文件

<?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>
    <!-- 配置日志 -->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <typeAliases>
        <package name="com.maj.domain"/>
    </typeAliases>

    <mappers>
        <package name="com.maj.dao"/>

    </mappers>
</configuration>

创建Service接口和实现类

package com.maj.service;

import com.maj.domain.Student;

import java.util.List;

public interface StudentService {
    int addStudent(Student student);

    List<Student> queryStudents();
}

package com.maj.service.impl;

import com.maj.dao.StudentDao;
import com.maj.domain.Student;
import com.maj.service.StudentService;

import java.util.List;

public class StudentServiceImpl implements StudentService {

    private StudentDao studentDao = null;

    public void setStudentDao(StudentDao studentDao) {
        this.studentDao = studentDao;
    }

    @Override
    public int addStudent(Student student) {
        int nums = studentDao.insertStudent(student);
        return nums;
    }

    @Override
    public List<Student> queryStudents() {
        List<Student> students = studentDao.selectStudents();
        return students;
    }
}

创建spring的配置文件

<?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">


    <!--声明数据源DateSource，作用是连接数据库-->
    <bean id="myDateSource" class="com.alibaba.druid.pool.DruidDataSource"
          init-method="init" destroy-method="close">
        <!-- set注入给DruidDataSource 提供连接数据库信息 -->
        <property name="url" value="jdbc:mysql://localhost:3306/springdb" />
        <property name="username" value="root" />
        <property name="password" value="maj6226543" />
        <property name="maxActive" value="20" />  <!--最大连接数-->
    </bean>

    <!--声明mybatis中提供的SqlSessionFactoryBean类，这个类内部创建SqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--把数据库连接池赋值给dataSource属性-->
        <property name="dataSource" ref="myDateSource"/>
        <!--
            mybatis主配置文件的位置
            configLocation属性是Resource类型，读取配置文件
                赋值使用value
                指定路径名使用  classpath:
        -->
        <property name="configLocation" value="classpath:mybatis.xml"/>
    </bean>

    <!--创建dao对象，使用SqlSession的getMapper(StudentDao.class)
        MapperScannerConfigurer: 在内部调用getMapper()生成每个dao接口的代理对象
    -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- sqlSessionFactoryBeanName属性指定 sqlSessionFactory-->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />


        <!--
        basePackage属性：
               给指定包下的dao接口都执行一次getMapper()方法得到*所有对象*放在spring容器中
                    对象名是dao接口名的首字母小写，例如StudentDao==》studentDao
               value值可以指定多个包（value="com.maj.dao1,com.maj.dao2,..."）
        -->
        <property name="basePackage" value="com.maj.dao" />

    </bean>

    <bean id="studentService" class="com.maj.service.impl.StudentServiceImpl">
        <property name="studentDao" ref="studentDao" />
    </bean>

</beans>

从属性文件读取数据库连接信息

为了便于维护，可以将数据库连接信息写入到属性文件中，使 Spring 配置文件从中读取数据。

属性文件名称自定义，但一般都是放在 resources目录下。

Spring 配置文件从属性文件中读取数据时，需要在<property/>的 value 属性中使用${ }，将在属性文件中定义的 key 括起来，以引用指定属性的值。

<context:property-placeholder/>方式：

• 该方式要求在 Spring 配置文件头部加入 spring-context.xsd 约束文件：

  xmlns:context="http://www.springframework.org/schema/context"

• <context:property-placeholder/>标签中有一个属性 location，用于指定属性文件的位置。

    <context:property-placeholder location="classpath:jdbc.properties" />

    <!--声明数据源DateSource，作用是连接数据库-->
    <bean id="myDateSource" class="com.alibaba.druid.pool.DruidDataSource"
          init-method="init" destroy-method="close">
        <!-- set注入给DruidDataSource 提供连接数据库信息 -->
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="maxActive" value="${jdbc.maxActive}" />  <!--最大连接数-->
    </bean>

创建测试类

package com.maj;

import com.maj.dao.StudentDao;
import com.maj.domain.Student;
import com.maj.service.StudentService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {
    /**
     * 测试容器中存在的对象
     */
    @Test
    public void test01() {
        String config = "applicationContext.xml";
        ApplicationContext ac = new ClassPathXmlApplicationContext(config);
        String[] names = ac.getBeanDefinitionNames();
        for (String name : names) {
            System.out.println("容器中对象名称：" + name);
            System.out.println(ac.getBean(name));
            System.out.println("----------------------");
        }
    }


    /**
     * 测试dao
     */
    @Test
    public void test02() {
        String config = "applicationContext.xml";
        ApplicationContext ac = new ClassPathXmlApplicationContext(config);
        StudentDao studentDao = (StudentDao) ac.getBean("studentDao");
        Student student = new Student(6, "惠子", 18);
        int count = studentDao.insertStudent(student);
        System.out.println("count=" + count);
    }

    /**
     * 测试Service
     */
    @Test
    public void test03() {
        String config = "applicationContext.xml";
        ApplicationContext ac = new ClassPathXmlApplicationContext(config);
        StudentService studentService = (StudentService) ac.getBean("studentService");
        Student student = new Student(7, "贞子", 18);
        int count = studentService.addStudent(student);
        System.out.println("count=" + count);
    }
}