eclipse 使用maven 搭建 springboot+mybatis + 多数据源

旧城等待， 2023-10-17 11:36 2阅读 0赞

本文转载至：[http://www.cnblogs.com/java-zhao/p/5413845.html][http_www.cnblogs.com_java-zhao_p_5413845.html]

在实际开发中，我们一个项目可能会用到多个数据库，通常一个数据库对应一个数据源。

代码结构：

![Center][]

**简要原理：**

1）DatabaseType列出所有的数据源的key---key

2）DatabaseContextHolder是一个线程安全的DatabaseType容器，并提供了向其中设置和获取DatabaseType的方法

3）DynamicDataSource继承AbstractRoutingDataSource并重写其中的方法determineCurrentLookupKey()，在该方法中使用DatabaseContextHolder获取当前线程的DatabaseType

4）MyBatisConfig中生成2个数据源DataSource的bean---value

5）MyBatisConfig中将1）和4）组成的key-value对写入到DynamicDataSource动态数据源的targetDataSources属性（当然，同时也会设置2个数据源其中的一个为DynamicDataSource的defaultTargetDataSource属性中）

6）将DynamicDataSource作为primary数据源注入到SqlSessionFactory的dataSource属性中去，并且该dataSource作为transactionManager的入参来构造DataSourceTran

sactionManager

7）使用的时候，在dao层或service层先使用DatabaseContextHolder设置将要使用的数据源key，然后再调用mapper层进行相应的操作，建议放在dao层去做（当然也可以使用spring aop+自定注解去做）

**注意：**在mapper层进行操作的时候，会先调用determineCurrentLookupKey()方法获取一个数据源（获取数据源：先根据设置去targetDataSources中去找，若没有，则选择defaultTargetDataSource），之后在进行数据库操作。

1、系统配置文件application.properties

#the read datasource
    jdbc.driverClassName = com.mysql.jdbc.Driver
    jdbc.url = jdbc:mysql://127.0.0.1:3306/master?zeroDateTimeBehavior=convertToNull&useUnicode=true&characterEncoding=utf-8
    jdbc.username = test
    jdbc.password = 123456
    
    #the write datasource
    jdbc2.driverClassName = com.mysql.jdbc.Driver
    jdbc2.url = jdbc:mysql://127.0.0.1:3306/master?zeroDateTimeBehavior=convertToNull&useUnicode=true&characterEncoding=utf-8
    jdbc2.username = root
    jdbc2.password = 123456
    
    mybatis.typeAliasesPackage=com.zzg.myboot.domain  
    mybatis.mapperLocations=classpath:mapper/*.xml

2、DatabaseType

package com.zzg.myboot.datasource;
    
    /**
     * 列出所有的数据源key（常用数据库名称来命名）
     * 注意：
     * 1）这里数据源与数据库是一对一的
     * 2）DatabaseType中的变量名称就是数据库的名称
     */
    public enum DatabaseType {
        read,write
    }

作用：列举数据源的key。

3、DatabaseContextHolder

package com.zzg.myboot.datasource;
    
    /**
     * 作用：
     * 1、保存一个线程安全的DatabaseType容器
     */
    public class DatabaseContextHolder {
        private static final ThreadLocal<DatabaseType> contextHolder = new ThreadLocal<DatabaseType>();
        
        public static void setDatabaseType(DatabaseType type){
            contextHolder.set(type);
        }
        
        public static DatabaseType getDatabaseType(){
            return contextHolder.get();
        }
    }

作用：构建一个DatabaseType容器，并提供了向其中设置和获取DatabaseType的方法

4、DynamicDataSource

package com.zzg.myboot.datasource;
    
    import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
    
    /**
     * 动态数据源（需要继承AbstractRoutingDataSource）
     */
    public class DynamicDataSource extends AbstractRoutingDataSource {
        protected Object determineCurrentLookupKey() {
            return DatabaseContextHolder.getDatabaseType();
        }
    }

作用：使用DatabaseContextHolder获取当前线程的DatabaseType

5、MyBatisConfig

package com.zzg.myboot.common;
    
    import java.util.HashMap;
    import java.util.Map;
    import java.util.Properties;
    import javax.sql.DataSource;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.mybatis.spring.SqlSessionFactoryBean;
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Primary;
    import org.springframework.core.env.Environment;
    import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
    import org.springframework.jdbc.datasource.DataSourceTransactionManager;
    import com.alibaba.druid.pool.DruidDataSourceFactory;
    import com.zzg.myboot.datasource.DatabaseType;
    import com.zzg.myboot.datasource.DynamicDataSource;
    
    
    /**
     * springboot集成mybatis的基本入口 1）创建数据源(如果采用的是默认的tomcat-jdbc数据源，则不需要)
     * 2）创建SqlSessionFactory 3）配置事务管理器，除非需要使用事务，否则不用配置
     */
    @Configuration // 该注解类似于spring配置文件
    @MapperScan(basePackages = "com.zzg.myboot.mapper")
    public class MyBatisConfig {
    
        @Autowired
        private Environment env;
    
        /**
         * 创建数据源(数据源的名称：方法名可以取为XXXDataSource(),XXX为数据库名称,该名称也就是数据源的名称)
         */
        @Bean
        public DataSource readDataSource() throws Exception {
            Properties props = new Properties();
            props.put("driverClassName", env.getProperty("jdbc.driverClassName"));
            props.put("url", env.getProperty("jdbc.url"));
            props.put("username", env.getProperty("jdbc.username"));
            props.put("password", env.getProperty("jdbc.password"));
            return DruidDataSourceFactory.createDataSource(props);
        }
    
        @Bean
        public DataSource writeDataSource() throws Exception {
            Properties props = new Properties();
            props.put("driverClassName", env.getProperty("jdbc2.driverClassName"));
            props.put("url", env.getProperty("jdbc2.url"));
            props.put("username", env.getProperty("jdbc2.username"));
            props.put("password", env.getProperty("jdbc2.password"));
            return DruidDataSourceFactory.createDataSource(props);
        }
    
        /**
         * @Primary 该注解表示在同一个接口有多个实现类可以注入的时候，默认选择哪一个，而不是让@autowire注解报错
         * @Qualifier 根据名称进行注入，通常是在具有相同的多个类型的实例的一个注入（例如有多个DataSource类型的实例）
         */
        @Bean
        @Primary
        public DynamicDataSource dataSource(@Qualifier("readDataSource") DataSource readDataSource,
                @Qualifier("writeDataSource") DataSource writeDataSource) {
            Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
            targetDataSources.put(DatabaseType.read, readDataSource);
            targetDataSources.put(DatabaseType.write, writeDataSource);
    
            DynamicDataSource dataSource = new DynamicDataSource();
            dataSource.setTargetDataSources(targetDataSources);// 该方法是AbstractRoutingDataSource的方法
            dataSource.setDefaultTargetDataSource(readDataSource);// 默认的datasource设置为myTestDbDataSource
    
            return dataSource;
        }
    
        /**
         * 根据数据源创建SqlSessionFactory
         */
        @Bean
        public SqlSessionFactory sqlSessionFactory(DynamicDataSource ds) throws Exception {
            SqlSessionFactoryBean fb = new SqlSessionFactoryBean();
            fb.setDataSource(ds);// 指定数据源(这个必须有，否则报错)
            // 下边两句仅仅用于*.xml文件，如果整个持久层操作不需要使用到xml文件的话（只用注解就可以搞定），则不加
            fb.setTypeAliasesPackage(env.getProperty("mybatis.typeAliasesPackage"));// 指定基包
            fb.setMapperLocations(
                    new PathMatchingResourcePatternResolver().getResources(env.getProperty("mybatis.mapperLocations")));//
    
            return fb.getObject();
        }
    
        /**
         * 配置事务管理器
         */
        @Bean
        public DataSourceTransactionManager transactionManager(DynamicDataSource dataSource) throws Exception {
            return new DataSourceTransactionManager(dataSource);
        }
    
    }

作用：

*  通过读取application.properties文件生成两个数据源（readDataSource、writeDataSource）
 *  使用以上生成的两个数据源构造动态数据源dataSource
    
     *  @Primary：指定在同一个接口有多个实现类可以注入的时候，默认选择哪一个，而不是让@Autowire注解报错（一般用于多数据源的情况下）
     *  @Qualifier：指定名称的注入，当一个接口有多个实现类的时候使用（在本例中，有两个DataSource类型的实例，需要指定名称注入）
     *  @Bean：生成的bean实例的名称是方法名（例如上边的@Qualifier注解中使用的名称是前边两个数据源的方法名，而这两个数据源也是使用@Bean注解进行注入的）
 *  通过动态数据源构造SqlSessionFactory和事务管理器（如果不需要事务，后者可以去掉）

6、使用

UserMapper.java

package com.zzg.myboot.mapper;
    
    import com.zzg.myboot.domain.User;
    
    public interface UserMapper {
    	int deleteByPrimaryKey(Long id);
    
    	int insert(User record);
    
    	int insertSelective(User record);
    
    	User selectByPrimaryKey(Long id);
    
    	int updateByPrimaryKeySelective(User record);
    
    	int updateByPrimaryKey(User record);
    }

UserDao.java

package com.zzg.myboot.dao;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Repository;
    
    import com.zzg.myboot.datasource.DatabaseContextHolder;
    import com.zzg.myboot.datasource.DatabaseType;
    import com.zzg.myboot.domain.User;
    import com.zzg.myboot.mapper.UserMapper;
    
    @Repository
    public class UserDao {
    	 @Autowired
    	 private UserMapper mapper;
    	 
    	 public int deleteByPrimaryKey(Long id){
    		 DatabaseContextHolder.setDatabaseType(DatabaseType.write);
    		 return mapper.deleteByPrimaryKey(id);
    	 }
    
    	 public	int insert(User record){
    		 DatabaseContextHolder.setDatabaseType(DatabaseType.write);
    		 return mapper.insert(record);
    	 }
    
    	 public	int insertSelective(User record){
    		 DatabaseContextHolder.setDatabaseType(DatabaseType.write);
    		 return mapper.insertSelective(record);
    	 }
    
    	 public	User selectByPrimaryKey(Long id){
    		 DatabaseContextHolder.setDatabaseType(DatabaseType.read);
    		 return mapper.selectByPrimaryKey(id);
    	 }
    
    	 public int updateByPrimaryKeySelective(User record){
    		 DatabaseContextHolder.setDatabaseType(DatabaseType.write);
    		 return mapper.updateByPrimaryKeySelective(record);
    	 }
    
    	 public	int updateByPrimaryKey(User record){
    		 DatabaseContextHolder.setDatabaseType(DatabaseType.write);
    		 return mapper.updateByPrimaryKey(record);
    	 }
    	 
    
    }

UserService.java

package com.zzg.myboot.service;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    import com.zzg.myboot.dao.UserDao;
    import com.zzg.myboot.domain.User;
    
    @Service
    public class UserService {
    	 @Autowired
    	 private UserDao dao;
    	 
    	 public int deleteByPrimaryKey(Long id){
    		 return dao.deleteByPrimaryKey(id);
    	 }
    
    	 public	int insert(User record){
    		 return dao.insert(record);
    	 }
    
    	 public	int insertSelective(User record){
    		 return dao.insertSelective(record);
    	 }
    
    	 public	User selectByPrimaryKey(Long id){
    		 return dao.selectByPrimaryKey(id);
    	 }
    
    	 public int updateByPrimaryKeySelective(User record){
    		 return dao.updateByPrimaryKeySelective(record);
    	 }
    
    	 public	int updateByPrimaryKey(User record){
    		 return dao.updateByPrimaryKey(record);
    	 }
    	 
    
    }

UserController.java

package com.zzg.myboot.controller;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    import com.zzg.myboot.domain.User;
    import com.zzg.myboot.service.UserService;
    
    import io.swagger.annotations.Api;
    import io.swagger.annotations.ApiOperation;
    
    @RestController
    @RequestMapping("/user")
    @Api("UserController相关api")
    public class UserController {
    	
    		@Autowired
    	    private UserService service;
    		
    		@ApiOperation("获取user信息,测试多数据源")
    	    @RequestMapping(value = "/getUser", method = RequestMethod.GET)
    	    public User getShop(@RequestParam("id") String id) {
    	        return service.selectByPrimaryKey(Long.parseLong(id));
    	    }
    
    }

user.sql 和UserMapper.xml

DROP TABLE IF EXISTS `user`;
    CREATE TABLE `user` (
      `id` bigint(19) NOT NULL auto_increment,
      `loginname` varchar(64) default NULL,
      `name` varchar(64) default NULL,
      `password` varchar(64) default NULL,
      `sex` tinyint(2) default '0',
      `age` tinyint(2) default '0',
      `usertype` tinyint(2) default '0',
      `status` tinyint(2) default '0',
      `organization_id` int(11) default '0',
      `createdate` datetime default NULL,
      `phone` varchar(20) default NULL,
      PRIMARY KEY  (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='用户';

<?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.zzg.myboot.mapper.UserMapper" >
      <resultMap id="BaseResultMap" type="com.zzg.myboot.domain.User" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="loginname" property="loginname" jdbcType="VARCHAR" />
        <result column="name" property="name" jdbcType="VARCHAR" />
        <result column="password" property="password" jdbcType="VARCHAR" />
        <result column="sex" property="sex" jdbcType="TINYINT" />
        <result column="age" property="age" jdbcType="TINYINT" />
        <result column="usertype" property="usertype" jdbcType="TINYINT" />
        <result column="status" property="status" jdbcType="TINYINT" />
        <result column="organization_id" property="organizationId" jdbcType="INTEGER" />
        <result column="createdate" property="createdate" jdbcType="TIMESTAMP" />
        <result column="phone" property="phone" jdbcType="VARCHAR" />
      </resultMap>
      <sql id="Base_Column_List" >
        id, loginname, name, password, sex, age, usertype, status, organization_id, createdate, 
        phone
      </sql>
      <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long" >
        select 
        <include refid="Base_Column_List" />
        from user
        where id = #{id,jdbcType=BIGINT}
      </select>
      <delete id="deleteByPrimaryKey" parameterType="java.lang.Long" >
        delete from user
        where id = #{id,jdbcType=BIGINT}
      </delete>
      <insert id="insert" parameterType="com.zzg.myboot.domain.User" >
        insert into user (id, loginname, name, 
          password, sex, age, 
          usertype, status, organization_id, 
          createdate, phone)
        values (#{id,jdbcType=BIGINT}, #{loginname,jdbcType=VARCHAR}, #{name,jdbcType=VARCHAR}, 
          #{password,jdbcType=VARCHAR}, #{sex,jdbcType=TINYINT}, #{age,jdbcType=TINYINT}, 
          #{usertype,jdbcType=TINYINT}, #{status,jdbcType=TINYINT}, #{organizationId,jdbcType=INTEGER}, 
          #{createdate,jdbcType=TIMESTAMP}, #{phone,jdbcType=VARCHAR})
      </insert>
      <insert id="insertSelective" parameterType="com.zzg.myboot.domain.User" >
        insert into user
        <trim prefix="(" suffix=")" suffixOverrides="," >
          <if test="id != null" >
            id,
          </if>
          <if test="loginname != null" >
            loginname,
          </if>
          <if test="name != null" >
            name,
          </if>
          <if test="password != null" >
            password,
          </if>
          <if test="sex != null" >
            sex,
          </if>
          <if test="age != null" >
            age,
          </if>
          <if test="usertype != null" >
            usertype,
          </if>
          <if test="status != null" >
            status,
          </if>
          <if test="organizationId != null" >
            organization_id,
          </if>
          <if test="createdate != null" >
            createdate,
          </if>
          <if test="phone != null" >
            phone,
          </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides="," >
          <if test="id != null" >
            #{id,jdbcType=BIGINT},
          </if>
          <if test="loginname != null" >
            #{loginname,jdbcType=VARCHAR},
          </if>
          <if test="name != null" >
            #{name,jdbcType=VARCHAR},
          </if>
          <if test="password != null" >
            #{password,jdbcType=VARCHAR},
          </if>
          <if test="sex != null" >
            #{sex,jdbcType=TINYINT},
          </if>
          <if test="age != null" >
            #{age,jdbcType=TINYINT},
          </if>
          <if test="usertype != null" >
            #{usertype,jdbcType=TINYINT},
          </if>
          <if test="status != null" >
            #{status,jdbcType=TINYINT},
          </if>
          <if test="organizationId != null" >
            #{organizationId,jdbcType=INTEGER},
          </if>
          <if test="createdate != null" >
            #{createdate,jdbcType=TIMESTAMP},
          </if>
          <if test="phone != null" >
            #{phone,jdbcType=VARCHAR},
          </if>
        </trim>
      </insert>
      <update id="updateByPrimaryKeySelective" parameterType="com.zzg.myboot.domain.User" >
        update user
        <set >
          <if test="loginname != null" >
            loginname = #{loginname,jdbcType=VARCHAR},
          </if>
          <if test="name != null" >
            name = #{name,jdbcType=VARCHAR},
          </if>
          <if test="password != null" >
            password = #{password,jdbcType=VARCHAR},
          </if>
          <if test="sex != null" >
            sex = #{sex,jdbcType=TINYINT},
          </if>
          <if test="age != null" >
            age = #{age,jdbcType=TINYINT},
          </if>
          <if test="usertype != null" >
            usertype = #{usertype,jdbcType=TINYINT},
          </if>
          <if test="status != null" >
            status = #{status,jdbcType=TINYINT},
          </if>
          <if test="organizationId != null" >
            organization_id = #{organizationId,jdbcType=INTEGER},
          </if>
          <if test="createdate != null" >
            createdate = #{createdate,jdbcType=TIMESTAMP},
          </if>
          <if test="phone != null" >
            phone = #{phone,jdbcType=VARCHAR},
          </if>
        </set>
        where id = #{id,jdbcType=BIGINT}
      </update>
      <update id="updateByPrimaryKey" parameterType="com.zzg.myboot.domain.User" >
        update user
        set loginname = #{loginname,jdbcType=VARCHAR},
          name = #{name,jdbcType=VARCHAR},
          password = #{password,jdbcType=VARCHAR},
          sex = #{sex,jdbcType=TINYINT},
          age = #{age,jdbcType=TINYINT},
          usertype = #{usertype,jdbcType=TINYINT},
          status = #{status,jdbcType=TINYINT},
          organization_id = #{organizationId,jdbcType=INTEGER},
          createdate = #{createdate,jdbcType=TIMESTAMP},
          phone = #{phone,jdbcType=VARCHAR}
        where id = #{id,jdbcType=BIGINT}
      </update>
    </mapper>

模拟测试数据库切换

第一情况：用户存在master库 select 权限，截图如下：

![Center 1][]

第二种情况：用户存在master库update 权限，截图如下：

![Center 2][]

[http_www.cnblogs.com_java-zhao_p_5413845.html]: http://www.cnblogs.com/java-zhao/p/5413845.html
[Center]: https://img-blog.csdn.net/20170315172026196?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhvdXpoaXdlbmdhbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 1]: https://img-blog.csdn.net/20170315173004145?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhvdXpoaXdlbmdhbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 2]: https://img-blog.csdn.net/20170315173046709?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhvdXpoaXdlbmdhbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center