Spring Boot集成Nacos动态刷新数据源

前言

因为项目需要，需要在项目运行过程中能够动态修改数据源（即：数据源的热更新）。这里以com.alibaba.druid.pool.DruidDataSource数据源为例

第一步：重写DruidAbstractDataSource类

这里为什么要重写这个类：因为DruidDataSource数据源在初始化后，就不允许再重新设置数据库的url和userName

package com.alibaba.druid.pool;
...

public abstract class DruidAbstractDataSource extends WrapperAdapter implements DruidAbstractDataSourceMBean, DataSource, DataSourceProxy, Serializable {

    ...

    public void setUrl(String jdbcUrl) {
        if (StringUtils.equals(this.jdbcUrl, jdbcUrl)) {
            return;
        }
        // 重写的时候，需要将这个判断注释掉，否则会报错
        // if (inited) {
        //     throw new UnsupportedOperationException();
        // }

        if (jdbcUrl != null) {
            jdbcUrl = jdbcUrl.trim();
        }

        this.jdbcUrl = jdbcUrl;

        // if (jdbcUrl.startsWith(ConfigFilter.URL_PREFIX)) {
        // this.filters.add(new ConfigFilter());
        // }
    }

    public void setUsername(String username) {
        if (StringUtils.equals(this.username, username)) {
            return;
        }
        // 重写的时候，需要将这个判断注释掉，否则会报错
        // if (inited) {
        //     throw new UnsupportedOperationException();
        // }

        this.username = username;
    }
}

重写的时候包路径不能变，只有这样类加载的时候才会优先加载重写后的类

第二步：配置动态获取Nacos配置信息

DruidConfiguration.java

import com.alibaba.druid.pool.DruidDataSource;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 描述：如果不使用代码手动初始化DataSource的话，监控界面的SQL监控会没有数据
 */
@Slf4j
@Configuration
@RefreshScope
@Data
public class DruidConfiguration {
    @Value("${spring.datasource.url}")
    private String dbUrl;

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

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

    @Value("${spring.datasource.driver-class-name}")
    private String driverClassName;

    // @Value("${spring.datasource.initialSize}")
    // private int initialSize;
    //
    // @Value("${spring.datasource.minIdle}")
    // private int minIdle;
    //
    // @Value("${spring.datasource.maxActive}")
    // private int maxActive;
    //
    // @Value("${spring.datasource.maxWait}")
    // private int maxWait;
    //
    // @Value("${spring.datasource.timeBetweenEvictionRunsMillis}")
    // private int timeBetweenEvictionRunsMillis;
    //
    // @Value("${spring.datasource.minEvictableIdleTimeMillis}")
    // private int minEvictableIdleTimeMillis;
    //
    // @Value("${spring.datasource.validationQuery}")
    // private String validationQuery;
    //
    // @Value("${spring.datasource.testWhileIdle}")
    // private boolean testWhileIdle;
    //
    // @Value("${spring.datasource.testOnBorrow}")
    // private boolean testOnBorrow;
    //
    // @Value("${spring.datasource.testOnReturn}")
    // private boolean testOnReturn;
    //
    // @Value("${spring.datasource.poolPreparedStatements}")
    // private boolean poolPreparedStatements;
    //
    // @Value("${spring.datasource.maxPoolPreparedStatementPerConnectionSize}")
    // private int maxPoolPreparedStatementPerConnectionSize;
    //
    // @Value("${spring.datasource.filters}")
    // private String filters;
    //
    // @Value("${spring.datasource.connectionProperties}")
    // private String connectionProperties;
    //
    // @Value("${spring.datasource.useGlobalDataSourceStat}")
    // private boolean useGlobalDataSourceStat;

    @Bean
    @RefreshScope
    public DruidDataSource dataSource() {
        DruidDataSource datasource = new DruidDataSource();
        datasource.setUrl(this.dbUrl);
        datasource.setUsername(username);
        datasource.setPassword(password);
        datasource.setDriverClassName(driverClassName);

        //configuration
        // datasource.setInitialSize(initialSize);
        // datasource.setMinIdle(minIdle);
        // datasource.setMaxActive(maxActive);
        // datasource.setMaxWait(maxWait);
        // datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        // datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        // datasource.setValidationQuery(validationQuery);
        // datasource.setTestWhileIdle(testWhileIdle);
        // datasource.setTestOnBorrow(testOnBorrow);
        // datasource.setTestOnReturn(testOnReturn);
        // datasource.setPoolPreparedStatements(poolPreparedStatements);
        // datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);
        // datasource.setUseGlobalDataSourceStat(useGlobalDataSourceStat);
        // try {
        //     datasource.setFilters(filters);
        // } catch (SQLException e) {
        //     log.error("druid configuration initialization filter: " + e);
        // }
        // datasource.setConnectionProperties(connectionProperties);
        return datasource;
    }
}

这里要注意增加@RefreshScope注解

第三步：手动刷新数据源

@GetMapping("/refresh")
public String refresh() throws SQLException
{
    DruidDataSource master = SpringUtils.getBean("dataSource");
    master.setUrl(druidConfiguration.getDbUrl());
    master.setUsername(druidConfiguration.getUsername());
    master.setPassword(druidConfiguration.getPassword());
    master.setDriverClassName(druidConfiguration.getDriverClassName());
    master.restart();
    return userName + "<>" + jdbcUrl + "----------" + druidConfiguration.getDbUrl();
}

SpringUtils.java

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

import java.util.Map;

@Component
public class SpringUtils implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringUtils.applicationContext = applicationContext;
    }

    public static <T> T getBean(String beanName) {
        if (applicationContext.containsBean(beanName)) {
            return (T) applicationContext.getBean(beanName);
        } else {
            return null;
        }
    }

    public static <T> Map<String, T> getBeansOfType(Class<T> baseType) {
        return applicationContext.getBeansOfType(baseType);
    }

    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
}