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SpringBoot多数据源切换实现代码(Mybaitis)

作者：胡安民　　发布时间：2021-11-07 11:15:50　

标签：springboot,多数据源,切换

前言

但是在实际业务场景中，数据量迅速增长，一个库一个表已经满足不了我们的需求的时候，我们就会考虑分库分表的操作，在springboot中如何实现多数据源，动态数据源切换，读写分离等操作。当你看到这篇文件那么你幸运了,下面直接提供终极通用版代码

如果是非Mybaitis的那么可以进行参照,原理都差不多

配置文件(YML)

spring:
datasource:
default-db-key: voidme
multi-db:
- voidme:
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: root
url: jdbc:mysql://192.168.42.153:3306/voidme?characterEncoding=utf8&autoReconnect=true&failOverReadOnly=false&maxReconnects=10&useSSL=false
- xcdef:
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: root
url: jdbc:mysql://192.168.42.153:3306/xcdef?characterEncoding=utf8&autoReconnect=true&failOverReadOnly=false&maxReconnects=10&useSSL=false

mybatis:
#1.classpath：只会到你的classes路径中查找找文件。
#2.classpath*：不仅会到classes路径，还包括jar文件中(classes路径)进行查找。
mapper-locations: classpath*:/mapper/**/*Mapper.xml # mapper映射文件位置
type-aliases-package: com.**.entity # 实体类所在的位置
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #用于控制台打印sql语句
map-underscore-to-camel-case: true #开启将带有下划线的表字段映射为驼峰格式的实体类属性

核心代码

DynamicDataSource

这个类用于获取数据源的(核心)

package com.dynamicdatadource.dynamic;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

public class DynamicDataSource extends AbstractRoutingDataSource {

@Value("${spring.datasource.default-db-key}")
private String defaultDbKey;

@Override
protected Object determineCurrentLookupKey() {
String currentDb = DynamicDataSourceService.currentDb();
if (currentDb == null) {
return defaultDbKey;
}
return currentDb;
}
}

DynamicDataSourceService

这个类是数据源切换工具,我们做了线程隔离了所以不用担心多线程数据源会混乱的问题

package com.dynamicdatadource.dynamic;

import com.application.ApplicationContextProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.jdbc.DataSourceBuilder;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

public class DynamicDataSourceService {
private static final Logger log = LoggerFactory.getLogger(DynamicDataSourceService.class);

private static final Map<Object, Object> dataSources = new HashMap<>();
private static final ThreadLocal<String> dbKeys = ThreadLocal.withInitial(() -> null);

/**
* 动态添加一个数据源
*
* @param name 数据源的key
* @param dataSource 数据源对象
*/
public static void addDataSource(String name, DataSource dataSource) {
DynamicDataSource dynamicDataSource = ApplicationContextProvider.getApplicationContext().getBean(DynamicDataSource.class);
dataSources.put(name, dataSource);
dynamicDataSource.setTargetDataSources(dataSources);
dynamicDataSource.afterPropertiesSet();
log.info("添加了数据源:{}",name);
}

/**
* @param name 数据源的key
* @param driverClassName 驱动
* @param url 数据库连接地址
* @param username 数据库账户
* @param password 数据库密码
*/
public static void addDataSource(String name, String driverClassName,String url,String username,String password) {
DataSourceBuilder<?> builder = DataSourceBuilder.create();
builder.driverClassName(driverClassName);
builder.username(username);
builder.password(password);
builder.url(url);
addDataSource(name,builder.build());
log.info("添加了数据源:{}",name);
}
/**
* 切换数据源
*/
public static void switchDb(String dbKey) {
dbKeys.set(dbKey);
}

/**
* 重置数据源(切换为默认的数据源)
*/
public static void resetDb() {
dbKeys.remove();
}

/**
* 获取当前数据源的key
*/
public static String currentDb() {
return dbKeys.get();
}
}

DynamicDataSourceConfig

将数据源配置到springboot中和初始化Mybaitis配置

package com.dynamicdatadource.dynamic;

import lombok.Data;
import org.apache.ibatis.logging.Log;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@Configuration
@ConfigurationProperties(prefix = "mybatis")
@Data
public class DynamicDataSourceConfig {

private String mapperLocations;
private String typeAliasesPackage;
@Data
public class MybatisConfiguration{
private String logImpl;
private boolean mapUnderscoreToCamelCase;
}
private MybatisConfiguration configuration=new MybatisConfiguration();

/**
* 动态数据源
*/
@Bean
public DynamicDataSource dynamicDataSource() {
DynamicDataSource dataSource = new DynamicDataSource();
Map<Object, Object> targetDataSources = new HashMap<>();
dataSource.setTargetDataSources(targetDataSources);
return dataSource;
}

/**
* 会话工厂Mybaitis
*/
@Bean
public SqlSessionFactoryBean sqlSessionFactoryBean() throws IOException, ClassNotFoundException {
org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
configuration.setMapUnderscoreToCamelCase(this.configuration.isMapUnderscoreToCamelCase()); //开启驼峰命名
configuration.setLogImpl((Class<? extends Log>) Class.forName(this.configuration.getLogImpl())); //控制台打印sql日志
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dynamicDataSource());
sqlSessionFactoryBean.setConfiguration(configuration);
PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
sqlSessionFactoryBean.setMapperLocations(resolver.getResources(mapperLocations));
sqlSessionFactoryBean.setTypeAliasesPackage(typeAliasesPackage);
return sqlSessionFactoryBean;
}

/**
* 事务管理器
*/
@Bean
public PlatformTransactionManager transactionManager() {
return new DataSourceTransactionManager(dynamicDataSource());
}
}

加载YML数据库配置类

package com.dynamicdatadource.config;

import com.dynamicdatadource.dynamic.DynamicDataSourceService;
import lombok.Data;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.sql.DataSource;
import java.util.List;
import java.util.Map;
import java.util.Set;

@Component
@Data
@ConfigurationProperties(prefix = "spring.datasource")
public class YmlDataSourceProvider {

private List<Map<String, DataSourceProperties>> multiDb;

private DataSource buildDataSource(DataSourceProperties prop) {
DataSourceBuilder<?> builder = DataSourceBuilder.create();
builder.driverClassName(prop.getDriverClassName());
builder.username(prop.getUsername());
builder.password(prop.getPassword());
builder.url(prop.getUrl());
return builder.build();
}

public void initDataSource() {
multiDb.forEach(map -> {
Set<String> keys = map.keySet();
keys.forEach(key -> {
DataSourceProperties properties = map.get(key);
DataSource dataSource = buildDataSource(properties);
DynamicDataSourceService.addDataSource(key, dataSource);
});
});
}

//在构造函数之后执行
@PostConstruct
public void init() {
initDataSource();
}
}

aop切换

package com.dynamicdatadource.aop;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.METHOD,ElementType.TYPE})//作用:方法和类
@Retention(RetentionPolicy.RUNTIME)
public @interface DynamicDataSourceAnno {
String key() default "";
}

package com.dynamicdatadource.aop;
import com.dynamicdatadource.dynamic.DynamicDataSourceService;
import org.apache.commons.lang.StringUtils;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

// 用于单独的请求或者类进行切换数据库
@Aspect
@Component
public class DynamicDataSourceAspect {
@Pointcut("@annotation(com.dynamicdatadource.aop.DynamicDataSourceAnno)")
public void dynamicDataSourceAnno() {
}

@Around("dynamicDataSourceAnno()")
public Object DynamicDataSourceAspectAroundAnno(ProceedingJoinPoint joinPoint) {
Object object = null;
try {
MethodSignature signature = (MethodSignature)joinPoint.getSignature();
DynamicDataSourceAnno dynamicDataSourceAnno = signature.getMethod().getAnnotation(DynamicDataSourceAnno.class);
String key = dynamicDataSourceAnno.key();
if (StringUtils.isNotBlank(key)) {
//切换为指定数据库
DynamicDataSourceService.switchDb(key);
}
object = joinPoint.proceed();
} catch (Throwable e) {
e.printStackTrace();
}finally {
//还原为默认配置
DynamicDataSourceService.resetDb();
}
return object;
}
// 还可以扩展包路径切换
}

效果

运行程序之后,就会将数据源加入到数据源列表中了

扩展

MysqlDataSourceInitialize

从数据库中将配置信息查询出来,然后动态添加到数据源列表中

package com.dao.config;

import com.dao.DatasourceDao;
import com.dynamicdatadource.aop.DynamicDataSourceAnno;
import com.dynamicdatadource.dynamic.DynamicDataSourceService;
import com.entity.DataSourceEneity;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.sql.DataSource;
import java.util.List;

//从数据库中查询出全部的数据源,添加到数据源容器中

/**
* 表结构如下:
*
* CREATE TABLE `t_datasource` (
* `id` int(11) NOT NULL,
* `key` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '绑定的key,用于数据源的切换',
* `url` text CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '数据库连接地址',
* `username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '数据库用户名',
* `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '数据库密码',
* `driverClassName` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '数据库驱动',
* `type` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '数据库类型: mysql ,oracle,..',
* `state` int(2) NOT NULL COMMENT '是否可用: 1可用 ,2不可用',
* PRIMARY KEY (`id`),
* UNIQUE KEY `key` (`key`)
* ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
*
* 上表要放入到默认数据源中的数据库里才行
*/
@Component
public class MysqlDataSourceInitialize implements ApplicationRunner {

@Autowired
private DatasourceDao datasourceDao;

//项目启动后执行初始化数据源
@Override
public void run(ApplicationArguments args) throws Exception {
try {
List<DataSourceEneity> dataSources = datasourceDao.getDataSources();
for (DataSourceEneity dataSource : dataSources) {
DynamicDataSourceService.addDataSource(dataSource.getKey(),dataSource.getDataSource());
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

DataSourceEneity实体类

@Data
public class DataSourceEneity {
private int id;
private String key;
private String url;
private String username;
private String password;
private String driverClassName;
private String type;
private int state;

public DataSource getDataSource() {
DataSourceBuilder<?> builder = DataSourceBuilder.create();
builder.driverClassName(driverClassName);
builder.username(username);
builder.password(password);
builder.url(url);
return builder.build();
}
}

来源：https://blog.csdn.net/weixin_45203607/article/details/123897803

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