程序猿學社的GitHub,歡迎Star
https://github.com/ITfqyd/cxyxs
本文已記錄到github,形成對應專題。
文章目錄
前言
前一篇文章,我們已經實現了通過springboot+MP實現多數據源,實際上一章的代碼,如果一個方法中操作多個數據源,如果中間出現異常,可能會存在一個入庫成功,另外一個入庫失敗的問題。而沒有保證多個數據源事務的一致性。、
- 爲了減少重複的代碼,在閱讀本文章之前,請先搭建好springboot集成多數據源環境。也是爲了減少重複的代碼。
【springboot專題】二十 springboot中如何配置多數據源
事務不一致問題
繼續在TestController類上加上如下代碼,兩個庫,爲了方便,我們就記錄爲test1和test2
@ApiOperation("同時向test1和test2中插入數據,增加指定某個事務的代碼,並故意在代碼中報錯")
@PostMapping("/saveEmp4")
@Transactional(value = "test2TransactionManager")
public String saveEmp4(Emp emp) {
int insert = empMapper1.insert(emp);
insert = empMapper2.insert(emp);
//故意報錯
String str= null;
System.out.println(str.toString()); //這裏會報錯
if(insert > 0){
return "插入成功";
}else{
return "插入失敗";
}
};
輸入http://localhost:8080/swagger-ui.html
點擊try it out 運行。
給一個小提示,注意看清楚,配置的事務是test2TransactionManager
大家覺得test1和test2這兩個庫的emp表,會有什麼變化?
有不少社友的答案,是不是test1和test2都不插入數據。
話不多說,檢查一波數據庫的身體
- 通過查看數據庫,可以發現test1數據源對應的庫插入成功一條“社長是個大帥哥”的記錄。 test2數據源對應的庫,表沒有變化。
- 分析現象,可以發現,test2數據源對應的庫,沒有變化成功,就是因爲我們在方法上配置test2TransactionManager的事務,說明只有test2纔會存在事務,test1實際上是沒有事務的。
- 通過查看@Transactional註解的源碼,alt+7(idea版本查詢類所有方法),通過仔細檢查,發現沒有一個字段能自定多個數據源。那怎麼辦?是不是就沒有別的辦法,可以解決多數據源事務的問題,別急。
- 一般多數據源中,解決事務問題,採用jta+atomikos
jta+atomikos
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.5.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.cloudtech</groupId>
<artifactId>moredatasource</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>moredatasource</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!--web-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- 增加thymeleaf座標 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!--簡化實體類-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!-- 熱部署 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<!--swagger2-->
<dependency>
<groupId>com.spring4all</groupId>
<artifactId>spring-boot-starter-swagger</artifactId>
<version>1.5.1.RELEASE</version>
</dependency>
<!--MP插件,簡化sql操作-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.3.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.18</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.6</version>
</dependency>
<!--swagger2-->
<dependency>
<groupId>com.spring4all</groupId>
<artifactId>spring-boot-starter-swagger</artifactId>
<version>1.5.1.RELEASE</version>
</dependency>
<!--jta+atomikos依賴-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jta-atomikos</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<!--解決編譯後,xml文件沒有過去的問題-->
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>include</include>
</includes>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
- 跟上個版本的pom.xml相比,只是多引入一個 jta+atomikos依賴。
application.yml
server:
port: 8888
spring:
datasource:
test1:
url: jdbc:mysql://localhost:3306/pro?useUnicode=true&characterEncoding=utf8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8
username: root
password: root
test2:
url: jdbc:mysql://localhost:3306/pro1?useUnicode=true&characterEncoding=utf8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8
username: root
password: root
mybatis-plus:
configuration:
##打印sql日誌,本地測試使用,生產環境不要使用,注意、注意、注意
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
####掃描swagger註解
swagger:
base-package: com.cxyxs
- 跟上個版本代碼相比,代碼有變動。
實體類
package com.cxyxs.moredatasource.entity;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import lombok.Data;
import org.omg.CORBA.IDLType;
/**
* Description:
* Author: 程序猿學社
* Date: 2020/3/7 12:03
* Modified By:
*/
@Data
public class Emp {
@TableId(type = IdType.AUTO)
private Integer id;
private String name;
private Integer age;
}
dao類
package com.cxyxs.moredatasource.test1.dao;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.cxyxs.moredatasource.entity.Emp;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;
import java.util.List;
/**
* Description:
* Author: 程序猿學社
* Date: 2020/3/7 12:01
* Modified By:
*/
@Repository
public interface EmpMapper1 extends BaseMapper<Emp>{
@Select("select * from emp")
public List<Emp> selectList();
/**
* 測試mapper
* @return
*/
public List<Emp> getAll();
}
mapper.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.cxyxs.moredatasource.test1.dao.EmpMapper1">
<!-- 根據區域名稱獲取區域代碼-->
<select id="getAll" resultType="com.cxyxs.moredatasource.entity.Emp">
select * from emp
</select>
</mapper>
- 注意:因爲test2跟test1包下的dao和mapper都是類似的,只是把test1或者EmpMapper1改爲test2和EmpMapper2就可以,這裏就不貼一些重複代碼。
讀取數據庫配置
Test1Config
package com.cxyxs.moredatasource.config;
import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
/**
* Description:V2.0版本的代碼
* Author: 程序猿學社
* Date: 2020/3/14 1:20
* Modified By:
*/
@ConfigurationProperties(prefix="spring.datasource.test1")
@Data
public class Test1Config {
private String url;
private String username;
private String password;
}
- @ConfigurationProperties讀取以對應配置爲前綴的值
- @Data使用該註解,可以不用set get
- 發現有一個報錯提示,別慌,按提示配置一下就行,需要在application啓動類裏面增加EnableConfigurationProperties註解
Test2Config
package com.cxyxs.moredatasource.config;
import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
/**
* Description:V2.0版本的代碼
* Author: 程序猿學社
* Date: 2020/3/14 1:20
* Modified By:
*/
@ConfigurationProperties(prefix="spring.datasource.test2")
@Data
public class Test2Config {
private String url;
private String username;
private String password;
}
啓動類
package com.cxyxs.moredatasource;
import com.cxyxs.moredatasource.config.Test1Config;
import com.cxyxs.moredatasource.config.Test2Config;
import com.spring4all.swagger.EnableSwagger2Doc;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.ComponentScan;
@SpringBootApplication
@ComponentScan(basePackages = {"com.cxyxs"})
@EnableSwagger2Doc
@EnableConfigurationProperties(value = { Test1Config.class, Test2Config.class })
public class MoredatasourceApplication {
public static void main(String[] args) {
SpringApplication.run(MoredatasourceApplication.class, args);
}
}
- @ConfigurationProperties註解一般是需要跟@Componen配套使用的,如果沒有指定,還有一種方式,就是@EnableConfigurationPropertie表示注入。
數據庫配置
DataSourceConfigPlus1
package com.cxyxs.moredatasource.config;
import com.atomikos.jdbc.AtomikosDataSourceBean;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.mysql.cj.jdbc.MysqlXADataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
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.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import javax.sql.DataSource;
import java.sql.SQLException;
@Configuration
@MapperScan(basePackages= {"com.cxyxs.moredatasource.test1.dao"},sqlSessionFactoryRef="test1SqlSessionFactory")
public class DataSourceConfigPlus1 {
// 配置數據源
@Bean("test1DataSource")
public DataSource testDataSource (Test1Config testConfig) throws SQLException {
//表示使用的是mysql數據庫
MysqlXADataSource mysqlXaDataSource = new MysqlXADataSource();
mysqlXaDataSource.setUrl(testConfig.getUrl());
mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
mysqlXaDataSource.setPassword(testConfig.getPassword());
mysqlXaDataSource.setUser(testConfig.getUsername());
mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
//Atomikos負責管理所有的事務
AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
xaDataSource.setXaDataSource(mysqlXaDataSource);
xaDataSource.setUniqueResourceName("test1DataSource");
return xaDataSource;
}
@Bean(name = "test1SqlSessionFactory")
public SqlSessionFactory testSqlSessionFactory(@Qualifier("test1DataSource") DataSource dataSource,@Qualifier("test1PaginationInterceptor") PaginationInterceptor paginationInterceptor)
throws Exception {
//注意,這裏引入的事MP的工廠,而不是mybatis的工廠SqlSessionFactoryBean
MybatisSqlSessionFactoryBean bean=new MybatisSqlSessionFactoryBean();
bean.setDataSource(dataSource);
//引入Mapper.xml文件的位置
Resource[] resources = new PathMatchingResourcePatternResolver()
.getResources("classpath*:/com/cxyxs/moredatasource/test1/mapper/*.xml");
bean.setMapperLocations(resources);
//保證MP的分頁插件可用
Interceptor[] plugins = new Interceptor[]{paginationInterceptor};
bean.setPlugins(plugins);
return bean.getObject();
}
/**
* 分頁插件
* @return
*/
@Bean("test1PaginationInterceptor")
public PaginationInterceptor paginationInterceptor(){
return new PaginationInterceptor();
}
@Bean(name = "test1SqlSessionTemplate")
public SqlSessionTemplate testSqlSessionTemplate(
@Qualifier("test1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
return new SqlSessionTemplate(sqlSessionFactory);
}
}
DataSourceConfigPlus2
package com.cxyxs.moredatasource.config;
import com.atomikos.jdbc.AtomikosDataSourceBean;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.mysql.cj.jdbc.MysqlXADataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
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.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import javax.sql.DataSource;
import java.sql.SQLException;
@Configuration
@MapperScan(basePackages= {"com.cxyxs.moredatasource.test2.dao"},sqlSessionFactoryRef="test2SqlSessionFactory")
public class DataSourceConfigPlus2 {
// 配置數據源
@Bean("test2DataSource")
public DataSource testDataSource (Test2Config testConfig) throws SQLException {
MysqlXADataSource mysqlXaDataSource = new MysqlXADataSource();
mysqlXaDataSource.setUrl(testConfig.getUrl());
mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
mysqlXaDataSource.setPassword(testConfig.getPassword());
mysqlXaDataSource.setUser(testConfig.getUsername());
mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
xaDataSource.setXaDataSource(mysqlXaDataSource);
xaDataSource.setUniqueResourceName("test2DataSource");
return xaDataSource;
}
@Bean(name = "test2SqlSessionFactory")
public SqlSessionFactory testSqlSessionFactory(@Qualifier("test2DataSource") DataSource dataSource,@Qualifier("test2PaginationInterceptor") PaginationInterceptor paginationInterceptor)
throws Exception {
MybatisSqlSessionFactoryBean bean=new MybatisSqlSessionFactoryBean();
bean.setDataSource(dataSource);
Resource[] resources = new PathMatchingResourcePatternResolver()
.getResources("classpath*:/com/cxyxs/moredatasource/test2/mapper/*.xml");
bean.setMapperLocations(resources);
Interceptor[] plugins = new Interceptor[]{paginationInterceptor};
bean.setPlugins(plugins);
return bean.getObject();
}
@Bean("test2PaginationInterceptor")
public PaginationInterceptor paginationInterceptor(){
return new PaginationInterceptor();
}
@Bean(name = "test2SqlSessionTemplate")
public SqlSessionTemplate testSqlSessionTemplate(
@Qualifier("test2SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
return new SqlSessionTemplate(sqlSessionFactory);
}
}
controller
package com.cxyxs.moredatasource.controller;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.cxyxs.moredatasource.entity.Emp;
import com.cxyxs.moredatasource.test1.dao.EmpMapper1;
import com.cxyxs.moredatasource.test2.dao.EmpMapper2;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
/**
* Description:
* Author: 程序猿學社
* Date: 2020/3/7 12:15
* Modified By:
*/
@RestController
@Api("測試多數據源接口")
public class TestController {
@Autowired
private EmpMapper1 empMapper1;
@Autowired
private EmpMapper2 empMapper2;
@ApiOperation("測試mybatis@select註解,通過test1數據庫實現")
@GetMapping("/getKing1")
public List getKing1(){
List<Emp> emps = empMapper1.selectList();
return emps;
};
@ApiOperation("測試mybatis@select註解,通過test2數據庫實現")
@GetMapping("/getKing2")
public List getKing2(){
List<Emp> emps = empMapper2.selectList();
return emps;
};
@ApiOperation("測試mybatis的mapper.xml文件調用,通過test1數據庫實現")
@GetMapping("/getKing3")
public List getKing3(){
List<Emp> emps = empMapper1.getAll();
return emps;
};
@ApiOperation("測試mybatis的mapper.xml文件調用,通過test2數據庫實現")
@GetMapping("/getKing4")
public List getKing4(){
List<Emp> emps = empMapper2.getAll();
return emps;
};
@ApiOperation("通過mp調用test1數據庫實現查詢")
@GetMapping("/getKing5")
public List getKing5(){
List<Emp> emps = empMapper1.selectList(null);
return emps;
};
@ApiOperation("通過mp調用test2數據庫實現查詢")
@GetMapping("/getKing6")
public List getKing6(){
List<Emp> emps = empMapper2.selectList(null);
return emps;
};
@ApiOperation("測試插入數據")
@PostMapping("/saveEmp1")
@Transactional
public String saveEmp(Emp emp) {
int insert = empMapper1.insert(emp);
if(insert > 0){
return "插入成功";
}else{
return "插入失敗";
}
};
@ApiOperation("測試給test1插入數據,增加指定某個事務的代碼")
@PostMapping("/saveEmp2")
@Transactional(value = "test1TransactionManager")
public String saveEmp2(Emp emp) {
int insert = empMapper1.insert(emp);
if(insert > 0){
return "插入成功";
}else{
return "插入失敗";
}
};
@ApiOperation("測試給test1插入數據,增加指定某個事務的代碼,並故意在代碼中報錯")
@PostMapping("/saveEmp3")
@Transactional(value = "test1TransactionManager")
public String saveEmp3(Emp emp) {
int insert = empMapper1.insert(emp);
//故意報錯
String str= null;
System.out.println(str.toString()); //這裏會報錯
if(insert > 0){
return "插入成功";
}else{
return "插入失敗";
}
};
@ApiOperation("同時向test1和test2中插入數據,增加指定某個事務的代碼,並故意在代碼中報錯")
@PostMapping("/saveEmp4")
@Transactional
public String saveEmp4(Emp emp) {
int insert = empMapper1.insert(emp);
insert = empMapper2.insert(emp);
//故意報錯
String str= null;
System.out.println(str.toString()); //這裏會報錯
if(insert > 0){
return "插入成功";
}else{
return "插入失敗";
}
};
@ApiOperation("同時向test1和test2中插入數據,增加指定某個事務的代碼,不故意報錯")
@PostMapping("/saveEmp5")
@Transactional
public String saveEmp5(Emp emp) {
int insert = empMapper1.insert(emp);
insert = empMapper2.insert(emp);
if(insert > 0){
return "插入成功";
}else{
return "插入失敗";
}
};
}
- 只需要關注saveEmp4和saveEmp5方法
saveEmp4方法,同時操作多個數據源,故意報錯
各位社友,猜猜兩個庫的變化?
- 直接公佈答案,就不檢查數據庫的身體,兩個庫,都插入失敗,說明事務生效。
saveEmp5方法,同時操作多個數據源,不報錯
各位社友,猜猜兩個庫的變化?
- 兩個庫都插入生成。
淺談jta+atomikos
優點:
- 通過jta+atomikos可以解決多數據源事務的問題,底層原理就是把多個事務,交給atomikos管理,這樣就可以幫我們解決@Transactional註解只能指定一個數據源的問題。
缺點:
- 需要拿到數據源才能通過atomikos來管理事務,在實際開發過程中,這點幾乎很難實現,所以一般在小項目中使用。在分佈式場景中,幾乎不採用這種方式。
源碼
覺得不錯,可以幫我點個贊,讓更多的人看到。
更多好看的內容,可以查看我的github專題,各個技術點會形成對應的專題。