SpringBoot-Mybatis多数据源查询数据库

一时失言乱红尘 2021-11-29 13:52 618阅读 0赞

### 文章目录 ###

*  用处
 *  示例层级结构图
 *  依赖
 *  配置文件
 *  数据源配置
 *  mapper层和其对应的xml文件
 *   *  mapper层
     *  xml文件
 *  service层
 *  测试

# 用处 #

多数据源，一般都来解决业务比较复杂需要连接不同的分库来支持业务的问题。

> 废话不多说直接上代码

# 示例层级结构图 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1pYWV85MjY0X0FORw_size_16_color_FFFFFF_t_70]  
[想查看自动生成mybatis代码工具请点击此处][mybatis]

# 依赖 #

pom.xml

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.3.4</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

# 配置文件 #

application.yml

spring:
      datasource:
        teacher:
          url: jdbc:mysql://localhost:3306/yanfa5?characterEncoding=utf8&useUnicode=true&timeZone=UTC
          driver-class-name: com.mysql.jdbc.Driver
          username: root
          password: root
        student:
          url: jdbc:mysql://localhost:3306/zzj0301?characterEncoding=utf8
          driver-class-name: com.mysql.jdbc.Driver
          username: root
          password: root
    logging:
      level:
        com.multi_mybatis.mapper: debug #显示SQL语句

注：此处的application.yml配置文件和用IDEA开发工具创建的SpringBoot工程中自动生成的application.properties配置文件作用相同，仅仅只是书写格式不同罢了

# 数据源配置 #

最关键的地方就是这块的配置了，一层一层的注入，首先创建DataSource，然后创建 SqlSessionFactory， 再创建事务，最后包装到 SqlSessionTemplate 中。其中需要指定分库的 mapper 文件地址，以及分库dao层代码。  
一个 student 库和一个 teacher 库，其中 teacher 位主库，在使用的过程中必须指定主库，不然会报错。

TeacherDataSourceConf.java

@Configuration
    @MapperScan(basePackages = "com.multi_mybatis.mapper.teacher", sqlSessionTemplateRef = "teacherSqlSessionTemplate")
    public class TeacherDataSourceConf {
        
    
        @Primary	//指定主库
        @Bean
        @ConfigurationProperties(prefix = "spring.datasource.teacher")
        public DataSource teacherDatasource() {
        
            return DataSourceBuilder.create().build();
        }
    
        @Bean
        public SqlSessionFactory teacherSqlSessionFactory() throws Exception {
        
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setDataSource(teacherDatasource());
            sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/mappers/teacher/*.xml"));
            return sqlSessionFactoryBean.getObject();
        }
    
        @Bean
        public DataSourceTransactionManager teacherTxMananger() {
        
            return new DataSourceTransactionManager(teacherDatasource());
        }
    
        @Bean
        public SqlSessionTemplate teacherSqlSessionTemplate() throws Exception {
        
            return new SqlSessionTemplate(teacherSqlSessionFactory());
        }
    }

StudentDataSourceConf.java

@Configuration
    @MapperScan(basePackages = "com.multi_mybatis.mapper.student", sqlSessionTemplateRef = "studentSqlSessionTemplate")
    public class StudentDataSourceConf {
        
    
        @Bean
        @ConfigurationProperties(prefix = "spring.datasource.student")
        public DataSource studentDatasource() {
        
            return DataSourceBuilder.create().build();
        }
    
        @Bean
        public SqlSessionFactory studentSqlSessionFactory() throws Exception {
        
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setDataSource(studentDatasource());
            sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/mappers/student/*.xml"));
            return sqlSessionFactoryBean.getObject();
        }
    
        @Bean
        public DataSourceTransactionManager studentTxMananger() {
        
            return new DataSourceTransactionManager(studentDatasource());
        }
    
        @Bean
        public SqlSessionTemplate studentSqlSessionTemplate() throws Exception {
        
            return new SqlSessionTemplate(studentSqlSessionFactory());
        }
    }

@MapperScan(basePackages = "com.multi_mybatis.mapper.teacher", sqlSessionTemplateRef = "teacherSqlSessionTemplate")
    @MapperScan(basePackages = "com.multi_mybatis.mapper.student", sqlSessionTemplateRef = "studentSqlSessionTemplate")

这块的注解就是指明了扫描 mapper 层，并且给 mapper 层注入指定的 SqlSessionTemplate。所有@Bean都需要按照命名指定正确。

# mapper层和其对应的xml文件 #

## mapper层 ##

TeacherMapper.java

public interface TeacherMapper {
        
        long countByExample(TeacherExample example);
    
        int deleteByExample(TeacherExample example);
    
        int deleteByPrimaryKey(Integer id);
    
        int insert(Teacher record);
    
        int insertSelective(Teacher record);
    
        List<Teacher> selectByExample(TeacherExample example);
    
        Teacher selectByPrimaryKey(Integer id);
    
        int updateByExampleSelective(@Param("record") Teacher record, @Param("example") TeacherExample example);
    
        int updateByExample(@Param("record") Teacher record, @Param("example") TeacherExample example);
    
        int updateByPrimaryKeySelective(Teacher record);
    
        int updateByPrimaryKey(Teacher record);
    }

StudentMapper.java

public interface StudentMapper {
        
        long countByExample(StudentExample example);
    
        int deleteByExample(StudentExample example);
    
        int deleteByPrimaryKey(Integer id);
    
        int insert(Student record);
    
        int insertSelective(Student record);
    
        List<Student> selectByExample(StudentExample example);
    
        Student selectByPrimaryKey(Integer id);
    
        int updateByExampleSelective(@Param("record") Student record, @Param("example") StudentExample example);
    
        int updateByExample(@Param("record") Student record, @Param("example") StudentExample example);
    
        int updateByPrimaryKeySelective(Student record);
    
        int updateByPrimaryKey(Student record);
    }

## xml文件 ##

TeacherMapper.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.multi_mybatis.mapper.teacher.TeacherMapper">
      <resultMap id="BaseResultMap" type="com.multi_mybatis.bean.Teacher">
        <id column="id" jdbcType="INTEGER" property="id" />
        <result column="name" jdbcType="VARCHAR" property="name" />
        <result column="age" jdbcType="INTEGER" property="age" />
      </resultMap>
      <sql id="Example_Where_Clause">
        <where>
          <foreach collection="oredCriteria" item="criteria" separator="or">
            <if test="criteria.valid">
              <trim prefix="(" prefixOverrides="and" suffix=")">
                <foreach collection="criteria.criteria" item="criterion">
                  <choose>
                    <when test="criterion.noValue">
                      and ${criterion.condition}
                    </when>
                    <when test="criterion.singleValue">
                      and ${criterion.condition} #{criterion.value}
                    </when>
                    <when test="criterion.betweenValue">
                      and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                    </when>
                    <when test="criterion.listValue">
                      and ${criterion.condition}
                      <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                        #{listItem}
                      </foreach>
                    </when>
                  </choose>
                </foreach>
              </trim>
            </if>
          </foreach>
        </where>
      </sql>
      <sql id="Update_By_Example_Where_Clause">
        <where>
          <foreach collection="example.oredCriteria" item="criteria" separator="or">
            <if test="criteria.valid">
              <trim prefix="(" prefixOverrides="and" suffix=")">
                <foreach collection="criteria.criteria" item="criterion">
                  <choose>
                    <when test="criterion.noValue">
                      and ${criterion.condition}
                    </when>
                    <when test="criterion.singleValue">
                      and ${criterion.condition} #{criterion.value}
                    </when>
                    <when test="criterion.betweenValue">
                      and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                    </when>
                    <when test="criterion.listValue">
                      and ${criterion.condition}
                      <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                        #{listItem}
                      </foreach>
                    </when>
                  </choose>
                </foreach>
              </trim>
            </if>
          </foreach>
        </where>
      </sql>
      <sql id="Base_Column_List">
        id, name, age
      </sql>
      <select id="selectByExample" parameterType="com.multi_mybatis.bean.TeacherExample" resultMap="BaseResultMap">
        select
        <if test="distinct">
          distinct
        </if>
        <include refid="Base_Column_List" />
        from teacher
        <if test="_parameter != null">
          <include refid="Example_Where_Clause" />
        </if>
        <if test="orderByClause != null">
          order by ${orderByClause}
        </if>
      </select>
      <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
        select 
        <include refid="Base_Column_List" />
        from teacher
        where id = #{id,jdbcType=INTEGER}
      </select>
      <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
        delete from teacher
        where id = #{id,jdbcType=INTEGER}
      </delete>
      <delete id="deleteByExample" parameterType="com.multi_mybatis.bean.TeacherExample">
        delete from teacher
        <if test="_parameter != null">
          <include refid="Example_Where_Clause" />
        </if>
      </delete>
      <insert id="insert" parameterType="com.multi_mybatis.bean.Teacher">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
          SELECT LAST_INSERT_ID()
        </selectKey>
        insert into teacher (name, age)
        values (#{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER})
      </insert>
      <insert id="insertSelective" parameterType="com.multi_mybatis.bean.Teacher">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
          SELECT LAST_INSERT_ID()
        </selectKey>
        insert into teacher
        <trim prefix="(" suffix=")" suffixOverrides=",">
          <if test="name != null">
            name,
          </if>
          <if test="age != null">
            age,
          </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
          <if test="name != null">
            #{name,jdbcType=VARCHAR},
          </if>
          <if test="age != null">
            #{age,jdbcType=INTEGER},
          </if>
        </trim>
      </insert>
      <select id="countByExample" parameterType="com.multi_mybatis.bean.TeacherExample" resultType="java.lang.Long">
        select count(*) from teacher
        <if test="_parameter != null">
          <include refid="Example_Where_Clause" />
        </if>
      </select>
      <update id="updateByExampleSelective" parameterType="map">
        update teacher
        <set>
          <if test="record.id != null">
            id = #{record.id,jdbcType=INTEGER},
          </if>
          <if test="record.name != null">
            name = #{record.name,jdbcType=VARCHAR},
          </if>
          <if test="record.age != null">
            age = #{record.age,jdbcType=INTEGER},
          </if>
        </set>
        <if test="_parameter != null">
          <include refid="Update_By_Example_Where_Clause" />
        </if>
      </update>
      <update id="updateByExample" parameterType="map">
        update teacher
        set id = #{record.id,jdbcType=INTEGER},
          name = #{record.name,jdbcType=VARCHAR},
          age = #{record.age,jdbcType=INTEGER}
        <if test="_parameter != null">
          <include refid="Update_By_Example_Where_Clause" />
        </if>
      </update>
      <update id="updateByPrimaryKeySelective" parameterType="com.multi_mybatis.bean.Teacher">
        update teacher
        <set>
          <if test="name != null">
            name = #{name,jdbcType=VARCHAR},
          </if>
          <if test="age != null">
            age = #{age,jdbcType=INTEGER},
          </if>
        </set>
        where id = #{id,jdbcType=INTEGER}
      </update>
      <update id="updateByPrimaryKey" parameterType="com.multi_mybatis.bean.Teacher">
        update teacher
        set name = #{name,jdbcType=VARCHAR},
          age = #{age,jdbcType=INTEGER}
        where id = #{id,jdbcType=INTEGER}
      </update>
    </mapper>

StudentMapper.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.multi_mybatis.mapper.student.StudentMapper">
      <resultMap id="BaseResultMap" type="com.multi_mybatis.bean.Student">
        <id column="id" jdbcType="INTEGER" property="id" />
        <result column="sname" jdbcType="VARCHAR" property="sname" />
        <result column="age" jdbcType="INTEGER" property="age" />
        <result column="gender" jdbcType="VARCHAR" property="gender" />
        <result column="nickname" jdbcType="VARCHAR" property="nickname" />
      </resultMap>
      <sql id="Example_Where_Clause">
        <where>
          <foreach collection="oredCriteria" item="criteria" separator="or">
            <if test="criteria.valid">
              <trim prefix="(" prefixOverrides="and" suffix=")">
                <foreach collection="criteria.criteria" item="criterion">
                  <choose>
                    <when test="criterion.noValue">
                      and ${criterion.condition}
                    </when>
                    <when test="criterion.singleValue">
                      and ${criterion.condition} #{criterion.value}
                    </when>
                    <when test="criterion.betweenValue">
                      and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                    </when>
                    <when test="criterion.listValue">
                      and ${criterion.condition}
                      <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                        #{listItem}
                      </foreach>
                    </when>
                  </choose>
                </foreach>
              </trim>
            </if>
          </foreach>
        </where>
      </sql>
      <sql id="Update_By_Example_Where_Clause">
        <where>
          <foreach collection="example.oredCriteria" item="criteria" separator="or">
            <if test="criteria.valid">
              <trim prefix="(" prefixOverrides="and" suffix=")">
                <foreach collection="criteria.criteria" item="criterion">
                  <choose>
                    <when test="criterion.noValue">
                      and ${criterion.condition}
                    </when>
                    <when test="criterion.singleValue">
                      and ${criterion.condition} #{criterion.value}
                    </when>
                    <when test="criterion.betweenValue">
                      and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                    </when>
                    <when test="criterion.listValue">
                      and ${criterion.condition}
                      <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                        #{listItem}
                      </foreach>
                    </when>
                  </choose>
                </foreach>
              </trim>
            </if>
          </foreach>
        </where>
      </sql>
      <sql id="Base_Column_List">
        id, sname, age, gender, nickname
      </sql>
      <select id="selectByExample" parameterType="com.multi_mybatis.bean.StudentExample" resultMap="BaseResultMap">
        select
        <if test="distinct">
          distinct
        </if>
        <include refid="Base_Column_List" />
        from student
        <if test="_parameter != null">
          <include refid="Example_Where_Clause" />
        </if>
        <if test="orderByClause != null">
          order by ${orderByClause}
        </if>
      </select>
      <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
        select 
        <include refid="Base_Column_List" />
        from student
        where id = #{id,jdbcType=INTEGER}
      </select>
      <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
        delete from student
        where id = #{id,jdbcType=INTEGER}
      </delete>
      <delete id="deleteByExample" parameterType="com.multi_mybatis.bean.StudentExample">
        delete from student
        <if test="_parameter != null">
          <include refid="Example_Where_Clause" />
        </if>
      </delete>
      <insert id="insert" parameterType="com.multi_mybatis.bean.Student">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
          SELECT LAST_INSERT_ID()
        </selectKey>
        insert into student (sname, age, gender, 
          nickname)
        values (#{sname,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER}, #{gender,jdbcType=VARCHAR}, 
          #{nickname,jdbcType=VARCHAR})
      </insert>
      <insert id="insertSelective" parameterType="com.multi_mybatis.bean.Student">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
          SELECT LAST_INSERT_ID()
        </selectKey>
        insert into student
        <trim prefix="(" suffix=")" suffixOverrides=",">
          <if test="sname != null">
            sname,
          </if>
          <if test="age != null">
            age,
          </if>
          <if test="gender != null">
            gender,
          </if>
          <if test="nickname != null">
            nickname,
          </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
          <if test="sname != null">
            #{sname,jdbcType=VARCHAR},
          </if>
          <if test="age != null">
            #{age,jdbcType=INTEGER},
          </if>
          <if test="gender != null">
            #{gender,jdbcType=VARCHAR},
          </if>
          <if test="nickname != null">
            #{nickname,jdbcType=VARCHAR},
          </if>
        </trim>
      </insert>
      <select id="countByExample" parameterType="com.multi_mybatis.bean.StudentExample" resultType="java.lang.Long">
        select count(*) from student
        <if test="_parameter != null">
          <include refid="Example_Where_Clause" />
        </if>
      </select>
      <update id="updateByExampleSelective" parameterType="map">
        update student
        <set>
          <if test="record.id != null">
            id = #{record.id,jdbcType=INTEGER},
          </if>
          <if test="record.sname != null">
            sname = #{record.sname,jdbcType=VARCHAR},
          </if>
          <if test="record.age != null">
            age = #{record.age,jdbcType=INTEGER},
          </if>
          <if test="record.gender != null">
            gender = #{record.gender,jdbcType=VARCHAR},
          </if>
          <if test="record.nickname != null">
            nickname = #{record.nickname,jdbcType=VARCHAR},
          </if>
        </set>
        <if test="_parameter != null">
          <include refid="Update_By_Example_Where_Clause" />
        </if>
      </update>
      <update id="updateByExample" parameterType="map">
        update student
        set id = #{record.id,jdbcType=INTEGER},
          sname = #{record.sname,jdbcType=VARCHAR},
          age = #{record.age,jdbcType=INTEGER},
          gender = #{record.gender,jdbcType=VARCHAR},
          nickname = #{record.nickname,jdbcType=VARCHAR}
        <if test="_parameter != null">
          <include refid="Update_By_Example_Where_Clause" />
        </if>
      </update>
      <update id="updateByPrimaryKeySelective" parameterType="com.multi_mybatis.bean.Student">
        update student
        <set>
          <if test="sname != null">
            sname = #{sname,jdbcType=VARCHAR},
          </if>
          <if test="age != null">
            age = #{age,jdbcType=INTEGER},
          </if>
          <if test="gender != null">
            gender = #{gender,jdbcType=VARCHAR},
          </if>
          <if test="nickname != null">
            nickname = #{nickname,jdbcType=VARCHAR},
          </if>
        </set>
        where id = #{id,jdbcType=INTEGER}
      </update>
      <update id="updateByPrimaryKey" parameterType="com.multi_mybatis.bean.Student">
        update student
        set sname = #{sname,jdbcType=VARCHAR},
          age = #{age,jdbcType=INTEGER},
          gender = #{gender,jdbcType=VARCHAR},
          nickname = #{nickname,jdbcType=VARCHAR}
        where id = #{id,jdbcType=INTEGER}
      </update>
    </mapper>

# service层 #

TeacherService.java

@Service
    public class TeacherService {
        
    
        @Autowired
        private TeacherMapper teacherMapper;
    
        public List<Teacher> queryAllTeacher() {
        
            return teacherMapper.selectByExample(new TeacherExample());
        }
    }

StudentService.java

@Service
    public class StudentService {
        
    
        @Autowired
        private StudentMapper studentMapper;
    
        public List<Student> queryAllStudent() {
        
            return studentMapper.selectByExample(new StudentExample());
        }
    }

# 测试 #

测试可以使用 SpringBootTest，也可以放到 Controller中，这里使用 SpringBootTest测试类。

MultiMybatisApplicationTests.java

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class MultiMybatisApplicationTests {
        
    
        @Autowired
        private TeacherService teacherService;
    
        @Autowired
        private StudentService studentService;
    
        @Test
        public void testTeacherService(){
        
            List<Teacher> teacherList = teacherService.queryAllTeacher();
            for (Teacher teacher : teacherList) {
        
                System.out.println("姓名:" + teacher.getName() + ",年龄:" + teacher.getAge());
            }
        }
    
        @Test
        public void testStudentService(){
        
            List<Student> studentList = studentService.queryAllStudent();
            for (Student Student : studentList) {
        
                System.out.println("姓名:" + Student.getSname() + ",年龄:" + Student.getAge());
            }
        }
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1pYWV85MjY0X0FORw_size_16_color_FFFFFF_t_70]: /images/20211129/ee5ccf2e1c4e42a9a31b808d57433852.png
[mybatis]: https://blog.csdn.net/ZXY_9264_ANG/article/details/96622676