注解方式切換數據源

1 注解類

@Target ({ ElementType.METHOD, ElementType.TYPE }) //注解作用的位置,ElemenetType.TYPE:類，接口（包括注解類型）或enum聲明
@Retention(RetentionPolicy.RUNTIME) //注解的生命周期，表示注解會被保留到什么階段，可以選擇編譯階段、類加載階段，或運行階段
@Documented //注解信息會被添加到Java文檔中
@Inherited //有該注解的類的子類會繼承該注解
public @interface DataSource
{
    /**
     * 切換數據源名稱
     */
    public DataSourceType value() default DataSourceType.SLAVE;
    //default DataSourceType.MASTER
}

DataSourceType是自定義的枚舉類

package com.kun.demo.enums;

public enum DataSourceType {
MASTER,
SLAVE
}

2 寫一個切面類給注解配置環繞通知

package com.kun.demo.aspect;

import com.kun.demo.anno.DataSource;
import com.kun.demo.util.DynamicDataSource;
import com.kun.demo.util.MultipleDatasource;
import com.sun.org.apache.regexp.internal.RE;
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.core.annotation.AnnotationUtils;
import org.springframework.stereotype.Component;

import java.util.Objects;

/**
 * @PackageName:com.kun.demo.aspect
 * @Description:
 * @Author 楊坤
 * @Date:2021/5/14 17:43
 */
@Aspect
@Component
public class Datasource_AroundAspect {
    @Pointcut("@annotation(com.kun.demo.anno.DataSource) || @within(com.kun.demo.anno.DataSource)")//@within能讓注解加載類上也生效
    public void pointcut(){}
    @Around("pointcut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        DataSource dataSource = getDataSource(point);//DataSource是注解

        if (null != dataSource)
        {
            System.out.println("dataSource.value().name()"+dataSource.value().name());
            MultipleDatasource.setDataSourceType(dataSource.value().name());
        }

        try
        {
            return point.proceed();
        }
        finally
        {
            // 銷毀數據源 在執行方法之后
            MultipleDatasource.cleanDataSourceType();
        }
    }
    /**
     * 獲取需要切換的數據源
     */
    public DataSource getDataSource(ProceedingJoinPoint point)
    {
        MethodSignature signature = (MethodSignature) point.getSignature();

        DataSource dataSource = AnnotationUtils.findAnnotation(signature.getMethod(), DataSource.class);//獲取方法上的注解
        if (Objects.nonNull(dataSource))
        {
            return dataSource;
        }
 return AnnotationUtils.findAnnotation(signature.getDeclaringType(), DataSource.class);//如果方法上沒加注解，就獲取類上的注解
    }
}
3 連接池的配置文件

# 數據源配置
spring:
    datasource:
#        type: com.alibaba.druid.pool.DruidDataSource
#        driverClassName: com.mysql.cj.jdbc.Driver
        druid:
            # 主庫數據源
            master:
                url: jdbc:mysql://192.168.10.99:3306/vue?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
                username: root
                password: root
            # 從庫數據源
            slave:
                # 從數據源開關/默認關閉
                enabled: false
                url: jdbc:mysql://192.168.10.99:3306/vue_slave?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
                username: root
                password: root
            # 初始連接數
            initialSize: 5
            # 最小連接池數量
            minIdle: 10
            # 最大連接池數量
            maxActive: 20
            # 配置獲取連接等待超時的時間
            maxWait: 60000
            # 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒
            timeBetweenEvictionRunsMillis: 60000
            # 配置一個連接在池中最小生存的時間，單位是毫秒
            minEvictableIdleTimeMillis: 300000
            # 配置一個連接在池中最大生存的時間，單位是毫秒
            maxEvictableIdleTimeMillis: 900000
            # 配置檢測連接是否有效
            validationQuery: SELECT 1 FROM DUAL
            testWhileIdle: true
            testOnBorrow: false
            testOnReturn: false
            webStatFilter:
                enabled: true
            statViewServlet:
                enabled: true
                # 設置白名單，不填則允許所有訪問
                allow:
                url-pattern: /druid/*
                # 控制台管理用戶名和密碼
                login-username: admin
                login-password: 123456
            filter:
                stat:
                    enabled: true
                    # 慢SQL記錄
                    log-slow-sql: true
                    slow-sql-millis: 1000
                    merge-sql: true
                wall:
                    config:
                        multi-statement-allow: true

記得在application.yml中添加進來連接池的配置文件

4 編寫連接池的配置文件

package com.kun.demo.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;

/**
 * druid 配置屬性
 *
 * @author ruoyi
 */
@Configuration //這個注解包括了@component注解 ,DruidConfig會交給容器管理
public class DruidConfig
{
    @Value("${spring.datasource.druid.initialSize}")
    private int initialSize;

    @Value("${spring.datasource.druid.minIdle}")
    private int minIdle;

    @Value("${spring.datasource.druid.maxActive}")
    private int maxActive;

    @Value("${spring.datasource.druid.maxWait}")
    private int maxWait;

    @Value("${spring.datasource.druid.timeBetweenEvictionRunsMillis}")
    private int timeBetweenEvictionRunsMillis;

    @Value("${spring.datasource.druid.minEvictableIdleTimeMillis}")
    private int minEvictableIdleTimeMillis;

    @Value("${spring.datasource.druid.maxEvictableIdleTimeMillis}")
    private int maxEvictableIdleTimeMillis;

    @Value("${spring.datasource.druid.validationQuery}")
    private String validationQuery;

    @Value("${spring.datasource.druid.testWhileIdle}")
    private boolean testWhileIdle;

    @Value("${spring.datasource.druid.testOnBorrow}")
    private boolean testOnBorrow;

    @Value("${spring.datasource.druid.testOnReturn}")
    private boolean testOnReturn;

    public DruidDataSource dataSource(DruidDataSource datasource)
    {
        /** 配置初始化大小、最小、最大 */
        datasource.setInitialSize(initialSize);
        datasource.setMaxActive(maxActive);
        datasource.setMinIdle(minIdle);
        /** 配置獲取連接等待超時的時間 */
        datasource.setMaxWait(maxWait);

        /** 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒 */
        datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);

        /** 配置一個連接在池中最小、最大生存的時間，單位是毫秒 */
        datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        datasource.setMaxEvictableIdleTimeMillis(maxEvictableIdleTimeMillis);

        /**
         * 用來檢測連接是否有效的sql，要求是一個查詢語句，常用select 'x'。如果validationQuery為null，testOnBorrow、testOnReturn、testWhileIdle都不會起作用。
         */
        datasource.setValidationQuery(validationQuery);
        /** 建議配置為true，不影響性能，並且保證安全性。申請連接的時候檢測，如果空閑時間大於timeBetweenEvictionRunsMillis，執行validationQuery檢測連接是否有效。 */
        datasource.setTestWhileIdle(testWhileIdle);
        /** 申請連接時執行validationQuery檢測連接是否有效，做了這個配置會降低性能。 */
        datasource.setTestOnBorrow(testOnBorrow);
        /** 歸還連接時執行validationQuery檢測連接是否有效，做了這個配置會降低性能。 */
        datasource.setTestOnReturn(testOnReturn);
        return datasource;
    }
}

5 編寫mybatis配置文件

package com.kun.demo.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import com.kun.demo.enums.DataSourceType;
import com.kun.demo.util.DynamicDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;
import java.util.*;

/**
 * @PackageName:com.kun.demo.config
 * @Description:
 * @Author 楊坤
 * @Date:2021/5/17 16:40
 */
@Configuration
public class MybatisConfig {
    @Autowired
    private Environment env;
@Bean
@ConfigurationProperties("spring.datasource.druid.master") //為了把spring.datasource.druid.master的屬性給return對象賦值
public DataSource masterDatasource(DruidConfig druidConfig){//@Bean方法的參數默認用@autowire方式注入
    DruidDataSource dataSource = DruidDataSourceBuilder.create().build();
    return druidConfig.dataSource(dataSource);//創建Druidconfig對象是為了把配置文件的公共屬性給return對象賦值
}
    @Bean
    @ConfigurationProperties("spring.datasource.druid.slave") //為了把spring.datasource.druid.slave的屬性給return對象賦值
    //@ConditionalOnProperty(prefix = "spring.datasource.druid.slave", name = "enabled", havingValue = "true")//配置文件中enabled這個值如果是true則Configuration注解生效
    public DataSource slaveDatasource(DruidConfig druidConfig){//@Bean方法的參數默認用@autowire方式注入
        DruidDataSource dataSource = DruidDataSourceBuilder.create().build();
        return druidConfig.dataSource(dataSource);
    }
    @Bean(name = "dynamicDataSource")
    public DynamicDataSource dataSource(@Qualifier("masterDatasource") DataSource testDatasource,@Qualifier("slaveDatasource") DataSource devDatasource)
    {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DataSourceType.MASTER.name(), testDatasource);
        targetDataSources.put(DataSourceType.SLAVE.name(), devDatasource);
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        dynamicDataSource.setTargetDataSources(targetDataSources);
        dynamicDataSource.setDefaultTargetDataSource(testDatasource);
        return dynamicDataSource;
    }
    @Bean(name = "sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("dynamicDataSource") DataSource dataSource) throws Exception
    {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*.xml"));
        return sessionFactory.getObject();
    }


}
6 編寫multifulDatasource用於給threadlocal類設置數據源

package com.kun.demo.util;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
 * @PackageName:com.kun.demo.util
 * @Description:
 * @Author 楊坤
 * @Date:2021/5/17 11:40
 */
public class MultipleDatasource  {
private static final ThreadLocal<String> dataSourceKey = new InheritableThreadLocal<String>();
public static final Logger log = LoggerFactory.getLogger(MultipleDatasource.class);
public static void setDataSourceType(String type){
    log.info("切換到數據源: "+type);
    dataSourceKey.set(type);
}
public static String getDataSourceType(){
    return dataSourceKey.get();
}
public static void cleanDataSourceType(){
    dataSourceKey.remove();
}
}

7 編寫DynamicDatasource用於選擇數據源

package com.kun.demo.util;

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

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

/**
 * @PackageName:com.kun.demo.util
 * @Description:
 * @Author 楊坤
 * @Date:2021/5/18 15:45
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return MultipleDatasource.getDataSourceType();
    }
}

啟動類上加

@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })//使用自定義的數據源
@MapperScan("com.kun.demo.mapper")//mapper接口掃描

用法:在service層的類或方法上加@DataSource(DataSourceType.MASTER) 就可以切換到master數據源,不加注解會mybatis配置文件配置的默認數據源