详解Spring Boot + Mybatis 实现动态数据源

create table `example` (

  `pk` bigint( 20 ) unsigned not null auto_increment comment '主键' ,

  `message` varchar( 100 ) not null ,

  `create_time` datetime not null comment '创建时间' ,

  `modify_time` datetime default null comment '生效时间' ,

  primary key (`pk`)

) engine=innodb auto_increment= 2 default charset=utf8 row_format=compact comment= '测试用例表'

<dependency>

    <groupid>org.springframework.boot</groupid>

    <artifactid>spring-boot-starter-web</artifactid>

   </dependency>

   <dependency>

    <groupid>org.springframework.boot</groupid>

    <artifactid>spring-boot-starter-test</artifactid>

    <scope>test</scope>

   </dependency>

   <dependency>

    <groupid>org.mybatis.spring.boot</groupid>

    <artifactid>mybatis-spring-boot-starter</artifactid>

    <version> 1.3 . 1 </version>

   </dependency>

   <!-- spring aop -->

   <dependency>

    <groupid>org.springframework.boot</groupid>

    <artifactid>spring-boot-starter-aop</artifactid>

   </dependency>

   <dependency>

    <groupid>mysql</groupid>

    <artifactid>mysql-connector-java</artifactid>

    <version> 5.1 . 8 </version>

   </dependency>

#数据库设置

spring.datasource.example.jdbc-url=jdbc:mysql: //localhost:3306/example?characterencoding=utf-8

spring.datasource.example.username=root

spring.datasource.example.password= 123456

spring.datasource.example.driver- class -name=com.mysql.jdbc.driver

package com.main.example.dynamic.datasource;

import org.springframework.boot.springapplication;

import org.springframework.boot.autoconfigure.springbootapplication;

import org.springframework.boot.autoconfigure.jdbc.datasourceautoconfiguration;

@springbootapplication (exclude = {

     datasourceautoconfiguration. class

})

public class dynamicdatasourceapplication {

  public static void main(string[] args) {

   springapplication.run(dynamicdatasourceapplication. class , args);

  }

}

package com.main.example.config.dao;

import com.main.example测试数据mon.dataenum;

import com.main.example测试数据mon.dynamicdatasource;

import org.mybatis.spring.sqlsessionfactorybean;

import org.springframework.boot.context.properties.configurationproperties;

import org.springframework.boot.jdbc.datasourcebuilder;

import org.springframework.context.annotation.bean;

import org.springframework.context.annotation.configuration;

import org.springframework.context.annotation.propertysource;

import org.springframework.core.io.support.pathmatchingresourcepatternresolver;

import org.springframework.jdbc.datasource.datasourcetransactionmanager;

import org.springframework.transaction.platformtransactionmanager;

import javax.sql.datasource;

import java.util.hashmap;

import java.util.map;

//数据库配置统一在config/mysql/db.properties中

@configuration

@propertysource (value = "classpath:config/mysql/db.properties" )

public class dbsourceconfig {

   private string typealiasespackage = "com.main.example.bean.**.*" ;

   @bean (name = "exampledatasource" )

   @configurationproperties (prefix = "spring.datasource.example" )

   public datasource exampledatasource() {

     return datasourcebuilder.create().build();

   }

   /*

    * 动态数据源

    * dbmap中存放数据源名称与数据源实例，数据源名称存于dataenum.dbsource中

    * setdefaulttargetdatasource方法设置默认数据源

    */

   @bean(name = "dynamicdatasource")

   public datasource dynamicdatasource() {

     dynamicdatasource dynamicdatasource = new dynamicdatasource();

     //配置多数据源

     map<object, object> dbmap = new hashmap();

     dbmap.put(dataenum.dbsource.example.getname(), exampledatasource());

     dynamicdatasource.settargetdatasources(dbmap);

     // 设置默认数据源

     dynamicdatasource.setdefaulttargetdatasource(exampledatasource());

     return dynamicdatasource;

   }

   /*

    * 数据库连接会话工厂

    * 将动态数据源赋给工厂

    * mapper存于resources/mapper目录下

    * 默认bean存于com.main.example.bean包或子包下，也可直接在mapper中指定

    */

   @bean (name = "sqlsessionfactory" )

   public sqlsessionfactorybean sqlsessionfactory() throws exception {

     sqlsessionfactorybean sqlsessionfactory = new sqlsessionfactorybean();

     sqlsessionfactory.setdatasource(dynamicdatasource());

     sqlsessionfactory.settypealiasespackage(typealiasespackage); //扫描bean

     pathmatchingresourcepatternresolver resolver = new pathmatchingresourcepatternresolver();

     sqlsessionfactory.setmapperlocations(resolver.getresources( "classpath*:mapper/*.xml" ));  // 扫描映射文件

     return sqlsessionfactory;

   }

   @bean

   public platformtransactionmanager transactionmanager() {

     // 配置事务管理, 使用事务时在方法头部添加@transactional注解即可

     return new datasourcetransactionmanager(dynamicdatasource());

   }

}

package com.main.example测试数据mon;

import org.springframework.jdbc.datasource.lookup.abstractroutingdatasource;

public class dynamicdatasource extends abstractroutingdatasource {

   @override

   protected object determinecurrentlookupkey() {

     return dbsourcecontext.getdbsource();

   }

}

package com.main.example测试数据mon;

import org.apache.log4j.logger;

public class dbsourcecontext {

   private static logger logger = logger.getlogger(dbsourcecontext. class );

   private static final threadlocal<string> dbcontext = new threadlocal<string>();

   public static void setdbsource(string source) {

     logger.debug( "set source ====>" + source);

     dbcontext.set(source);

   }

   public static string getdbsource() {

     logger.debug( "get source ====>" + dbcontext.get());

     return dbcontext.get();

   }

   public static void cleardbsource() {

     dbcontext.remove();

   }

}

package com.main.example.config.dao;

import java.lang.annotation.*;

/**

  * 动态数据源注解

  * @author

  * @date april 12, 2019

  */

@target ({elementtype.method, elementtype.type})

@retention (retentionpolicy.runtime)

@documented

public @interface dbsource {

   /**

    * 数据源key值

    * @return

    */

   string value();

}

package com.main.example.config.dao;

import com.main.example测试数据mon.dbsourcecontext;

import org.apache.log4j.logger;

import org.aspectj.lang.joinpoint;

import org.aspectj.lang.annotation.after;

import org.aspectj.lang.annotation.aspect;

import org.aspectj.lang.annotation.before;

import org.springframework.core.annotation.order;

import org.springframework.stereotype测试数据ponent;

/**

  * 动态数据源切换处理器

  * @author linzhibao

  * @date april 12, 2019

  */

@aspect

@order (- 1 ) // 该切面应当先于 @transactional 执行

@component

public class dynamicdatasourceaspect {

   private static logger logger = logger.getlogger(dynamicdatasourceaspect. class );

   /**

    * 切换数据源

    * @param point

    * @param dbsource

    */

   //@before("@annotation(dbsource)") 注解在对应方法，拦截有@dbsource的方法

   //注解在类对象，拦截有@dbsource类下所有的方法

   @before ( "@within(dbsource)" )

   public void switchdatasource(joinpoint point, dbsource dbsource) {

       // 切换数据源

       dbsourcecontext.setdbsource(dbsource.value());

   }

   /**

    * 重置数据源

    * @param point

    * @param dbsource

    */

   //注解在类对象，拦截有@dbsource类下所有的方法

   @after ( "@within(dbsource)" )

   public void restoredatasource(joinpoint point, dbsource dbsource) {

     // 将数据源置为默认数据源

     dbsourcecontext.cleardbsource();

   }

}

package com.main.example.dao;

import com.main.example测试数据mon.dataenum;

import com.main.example.config.dao.dbsource;

import org.springframework.context.annotation.bean;

import org.springframework.stereotype测试数据ponent;

import javax.annotation.resource;

import java.util.list;

@component ( "exampledao" )

//切换数据源注解，以dataenum.dbsource中的值为准

@dbsource ( "example" )

public class exampledao extends daobase {

   private static final string mapper_name_space = "com.main.example.dao.examplemapper" ;

   public list<string> selectallmessages() {

     return selectlist(mapper_name_space, "selectallmessages" );

   }

}

package com.main.example.dao;

import org.springframework.beans.factory.annotation.autowired;

import org.springframework.web.bind.annotation.requestmapping;

import org.springframework.web.bind.annotation.restcontroller;

import java.util.arraylist;

import java.util.list;

@restcontroller

public class testexampledao {

   @autowired

   exampledao exampledao;

   @requestmapping (value = "/test/example" )

   public list<string> selectallmessages() {

     try {

       list<string> ldata = exampledao.selectallmessages();

       if (ldata == null ){system.out.println( "*********it is null.***********" ); return null ;}

       for (string d : ldata) {

         system.out.println(d);

       }

       return ldata;

     } catch (exception e) {

       e.printstacktrace();

     }

     return new arraylist<>();

   }

}

<?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.main.example.dao.examplemapper" >

   <select id= "selectallmessages" resulttype= "java.lang.string" >

     select

     message

     from example

   </select>

</mapper>

@propertysource (value = "classpath:config/mysql/db.properties" )

@configurationproperties (prefix = "spring.datasource.example" )

@springbootapplication (exclude = {

     datasourceautoconfiguration. class

})