MyBatis使用Zookeeper保存数据库的配置可动态刷新的实现代码

核心关键点: 封装一个DataSource, 重写 getConnection 就可以实现

我们一步一步来看.

环境: Spring Cloud + MyBatis

MyBatis常规方式下配置数据源: 使用Spring的Configuration

package com.cnscud.cavedemo.fundmain.config;


import com.cnscud.xpower.dbn.SimpleDBNDataSourceFactory;
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.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.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;

import javax.sql.DataSource;

/**
 * Database Config 多数据源配置: 主数据源.
 *
 * @author Felix Zhang 2021-08-02 17:30
 * @version 1.0.0
 */
@Configuration
@MapperScan(basePackages = {"com.cnscud.cavedemo.fundmain.dao"},
        sqlSessionFactoryRef = "sqlSessionFactoryMainDataSource")
public class MainDataSourceConfig {



    //常规配置: 使用application.yml里面的配置.
    @Primary
    @Bean(name = "mainDataSource")
    @ConfigurationProperties("spring.datasource.main")
    public DataSource mainDataSource() throws Exception {
        return DataSourceBuilder.create().build();
    }

    @Primary
    @Bean(name = "sqlSessionFactoryMainDataSource")
    public SqlSessionFactory sqlSessionFactoryMainDataSource(@Qualifier("mainDataSource") DataSource mainDataSource) throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        //org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        //configuration.setMapUnderscoreToCamelCase(true);
        //factoryBean.setConfiguration(configuration);
        factoryBean.setConfigLocation(new PathMatchingResourcePatternResolver().getResource("classpath:mybatis-config.xml"));

        // 使用mainDataSource数据源, 连接mainDataSource库
        factoryBean.setDataSource(mainDataSource);

        //下边两句仅仅用于*.xml文件，如果整个持久层操作不需要使用到xml文件的话（只用注解就可以搞定），则不加
        //指定entity和mapper xml的路径
        //factoryBean.setTypeAliasesPackage("com.cnscud.cavedemo.fundmain.model");
        factoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:com/cnscud/cavedemo/fundmain/mapper/*.xml"));
        return factoryBean.getObject();
    }

    @Primary
    @Bean
    public SqlSessionTemplate sqlSessionTemplateMainDataSource(@Qualifier("sqlSessionFactoryMainDataSource") SqlSessionFactory sqlSessionTemplateMainDataSource) throws Exception {

        //使用注解中配置的Factory
        return new SqlSessionTemplate(sqlSessionTemplateMainDataSource);
    }

    @Primary
    @Bean
    public PlatformTransactionManager mainTransactionManager(@Qualifier("mainDataSource") DataSource prodDataSource) {
        return new DataSourceTransactionManager(prodDataSource);
    }
}

这里面获取数据源的关键函数是 mainDataSource, 我们自己来实现就好了:

因为这个是一次性的工作, 所以我们无法修改DataSource的指向, 只能在DataSource内部做文章, 所以我们需要自己实现一个DataSource.

其中的步骤比较多, 我们来看看最终结果:

最终的DataSourceWrapper

它完全封装了一个DataSource, 自己并没有任何DataSource的功能:

package com.cnscud.xpower.dbn;

import javax.sql.DataSource;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.logging.Logger;

/**
 * Datasource wrapper, 为了方便动态创建DataSource.
 *
 * @author Felix Zhang 2021-08-05 14:14
 * @version 1.0.0
 */
public class DynamicByZookeeperDataSourceWrapper implements DataSource {

    protected SimpleDBNConnectionPool simpleDBNConnectionPool;
    protected String bizName;

    public DynamicByZookeeperDataSourceWrapper(SimpleDBNConnectionPool simpleDBNConnectionPool, String bizName) {
        this.simpleDBNConnectionPool = simpleDBNConnectionPool;
        this.bizName = bizName;
    }

    protected DataSource pickDataSource() throws SQLException{
        return simpleDBNConnectionPool.getDataSource(bizName);
    }

    @Override
    public Connection getConnection() throws SQLException {
        return pickDataSource().getConnection();
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return pickDataSource().getConnection(username, password);
    }

    @Override
    public  T unwrap(Class iface) throws SQLException {
        return pickDataSource().unwrap(iface);
    }

    @Override
    public boolean isWrapperFor(Class iface) throws SQLException {
        return pickDataSource().isWrapperFor(iface);
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return pickDataSource().getLogWriter();
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {
        pickDataSource().setLogWriter(out);
    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
        pickDataSource().setLoginTimeout(seconds);
    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return pickDataSource().getLoginTimeout();
    }

    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        throw new SQLFeatureNotSupportedException();
    }
}

SimpleDBNConnectionPool

支持多个数据源的暂存池, 可以根据name获取不同的数据库DataSource实例:

这个类负责创建DataSource, 保存在Map里. 并且能监听Zookeeper的变化, 一旦侦听到变化, 就close现有的DataSource.

package com.cnscud.xpower.dbn;

import com.github.zkclient.IZkDataListener;
import com.zaxxer.hikari.HikariDataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import static java.lang.String.format;

/**
 * The simple datasource pool.
 *
 * 根据名字存放多个数据库的DataSource, 并且会监听Zookeeper配置, 动态重建.
 *
 * @author adyliu ([email protected])
 * @since 2011-7-27
 */
public class SimpleDBNConnectionPool {

    final Logger logger = LoggerFactory.getLogger(getClass());


    private Map instances = new ConcurrentHashMap<>();
    private final Set watcherSchema = new HashSet();


    public DataSource getInstance(String bizName) {
        try {
            return findDbInstance(bizName);
        }
        catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    public Connection getConnection(String bizName) throws SQLException {
        DataSource ds = getDataSource(bizName);
        return ds.getConnection();
    }

    public DataSource getDataSource(String bizName) throws SQLException {
        return findDbInstance(bizName);
    }


    protected void destroyInstance(final String bizName) {
        synchronized (instances) {
            DataSource oldInstanceIf = instances.remove(bizName);
            logger.warn(format("destoryInstance %s and %s", bizName, oldInstanceIf != null ? "close datasource" : "do nothing"));
            if (oldInstanceIf != null) {
                closeDataSource(oldInstanceIf);
            }
        }
    }

    protected void closeDataSource(DataSource ds) {
        if (ds instanceof HikariDataSource) {
            try {
                ((HikariDataSource) ds).close();
            }
            catch (Exception e) {
                logger.error("Close datasource failed. ", e);
            }
        }
    }


    private DataSource createInstance(Map dbcfg) {
        return new SimpleDataSourceBuilder().buildDataSource(dbcfg);
    }


    private DataSource findDbInstance(final String bizName) throws SQLException {
        DataSource ins = instances.get(bizName);
        if (ins != null) {
            return ins;
        }
        synchronized (instances) {// 同步操作
            ins = instances.get(bizName);
            if (ins != null) {
                return ins;
            }
            boolean success = false;
            try {
                Map dbcfg = SchemeNodeHelper.getInstance(bizName);
                if (dbcfg == null) {
                    throw new SQLException("No such datasouce: " + bizName);
                }
                ins = createInstance(dbcfg);
                //log.warn("ins put "+ins);
                instances.put(bizName, ins);


                if (watcherSchema.add(bizName)) {
                    SchemeNodeHelper.watchInstance(bizName, new IZkDataListener() {

                        public void handleDataDeleted(String dataPath) throws Exception {
                            logger.warn(dataPath + " was deleted, so destroy the bizName " + bizName);
                            destroyInstance(bizName);
                        }

                        public void handleDataChange(String dataPath, byte[] data) throws Exception {
                            logger.warn(dataPath + " was changed, so destroy the bizName " + bizName);
                            destroyInstance(bizName);
                        }
                    });
                }
                success = true;
            }
            catch (SQLException e) {
                throw e;
            }
            catch (Throwable t) {
                throw new SQLException("cannot build datasource for bizName: " + bizName, t);
            }
            finally {
                if (!success) {
                    instances.remove(bizName);
                }
            }
        }
        return ins;
    }

}

真正创建DataSource的代码:

package com.cnscud.xpower.dbn;

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import org.apache.commons.lang.StringUtils;

import java.util.Map;

/**
 * Hikari DataSource.
 *
 * 思考: 可以根据参数里面的类型来使用不同的库创建DataSource, 例如Druid. (默认为HikariDataSource)
 *
 *
 * @author Felix Zhang 2021-08-05 11:14
 * @version 1.0.0
 */
public class SimpleDataSourceBuilder {


    public HikariDataSource buildDataSource(Map args) {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl(getUrl(args));
        config.setUsername(args.get("username"));
        config.setPassword(args.get("password"));
        config.setDriverClassName(getDriverClassName(args));

        String maximumPoolSizeKey = "maximum-pool-size";
        int maximumPoolSize = 30;
        if(StringUtils.isNotEmpty(args.get(maximumPoolSizeKey))){
            maximumPoolSize = Integer.parseInt(args.get(maximumPoolSizeKey));
        }

        config.addDataSourceProperty("cachePrepStmts", "true"); //是否自定义配置，为true时下面两个参数才生效
        config.addDataSourceProperty("prepStmtCacheSize", maximumPoolSize); //连接池大小默认25，官方推荐250-500
        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048"); //单条语句最大长度默认256，官方推荐2048
        config.addDataSourceProperty("useServerPrepStmts", "true"); //新版本MySQL支持服务器端准备，开启能够得到显著性能提升
        config.addDataSourceProperty("useLocalSessionState", "true");
        config.addDataSourceProperty("useLocalTransactionState", "true");
        config.addDataSourceProperty("rewriteBatchedStatements", "true");
        config.addDataSourceProperty("cacheResultSetMetadata", "true");
        config.addDataSourceProperty("cacheServerConfiguration", "true");
        config.addDataSourceProperty("elideSetAutoCommits", "true");
        config.addDataSourceProperty("maintainTimeStats", "false");

        config.setMaximumPoolSize(maximumPoolSize); //
        config.setMinimumIdle(10);//最小闲置连接数，默认为0
        config.setMaxLifetime(600000);//最大生存时间
        config.setConnectionTimeout(30000);//超时时间30秒
        config.setIdleTimeout(60000);

        config.setConnectionTestQuery("select 1");

        return new HikariDataSource(config);
    }

    private String getDriverClassName(Map args) {
        return args.get("driver-class-name");
    }

    private String getUrl(Map args) {
        return args.get("jdbc-url") == null ? args.get("url"): args.get("jdbc-url");
    }
}

为了方便读取Zookeeper节点, 还有个SchemeNodeHelper:

支持两种配置文件的方式 json或者Properties格式:

package com.cnscud.xpower.dbn;

import com.cnscud.xpower.configcenter.ConfigCenter;
import com.cnscud.xpower.utils.Jsons;
import com.github.zkclient.IZkDataListener;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

/**
 * 从Zookeeper的 /xpower/dbn节点下读取数据库配置.
 * 内容支持两种格式: json或者properties格式.
 *
 * JSON格式如下:
 * {
 *   "jdbc-url": "jdbc:mysql://127.0.0.1:3306/cavedemo?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC",
 *   "username": "dbuser",
 *   "password": "yourpassword",
 *   "driver-class-name": "com.mysql.cj.jdbc.Driver"
 * }
 *
 * Properties格式如下:
 *  jdbc-url: jdbc:mysql://127.0.0.1:3306/cavedemo?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC
 *  username: dbuser
 *  password: password
 *  driver-class-name: com.mysql.cj.jdbc.Driver
 *
 * @author Felix Zhang
 * @since 2021-8-5
 */
public class SchemeNodeHelper {

    static final Logger logger = LoggerFactory.getLogger(SchemeNodeHelper.class);

    //支持两种格式: json, properties
    public static Map getInstance(final String instanceName) throws Exception {
        String data = ConfigCenter.getInstance().getDataAsString("/xpower/dbn/" + instanceName);
        if(StringUtils.isEmpty(data)){
            return null;
        }

        data = data.trim();
        if (data.startsWith("{")) {
            //as json
            Map swap = Jsons.fromJson(data, Map.class);
            Map result = new HashMap<>();

            if (swap != null) {
                for (String name : swap.keySet()) {
                    result.put(name.toLowerCase(), swap.get(name));
                }
            }

            return result;
        }
        else {
            //as properties
            Properties props = new Properties();
            try {
                props.load(new StringReader(data));
            }
            catch (IOException e) {
                logger.error("loading global config failed", e);
            }

            Map result = new HashMap<>();

            for (String name : props.stringPropertyNames()) {
                result.put(name.toLowerCase(), props.getProperty(name));
            }

            return result;
        }
    }

    public static void watchInstance(final String bizName, final IZkDataListener listener) {
        final String path = "/xpower/dbn/" + bizName;
        ConfigCenter.getInstance().subscribeDataChanges(path, listener);
    }
}

实际应用

最后在MyBatis项目中, 替换原有MainDataSource代码为:

/**
     * 添加@Primary注解，设置默认数据源，事务管理器.
     * 此处使用了一个可以动态重建的DataSource, 如果Zookeeper配置改变,会动态重建.
     */
    @Primary
    @Bean(name = "mainDataSource")
    public DataSource mainDataSource() throws Exception {
        return SimpleDBNDataSourceFactory.getInstance().getDataSource("cavedemo");
    }

运行项目, 发现可以连上数据库, 并且不重启项目的情况下, 动态修改数据库配置, 能自动重连.

项目代码:

https://github.com/cnscud/xpower/tree/main/xpower-main/src/main/java/com/cnscud/xpower/dbn

其中用到的 ConfigCenter 也在这个项目里, 也可以自己实现, 就可以脱离本项目了.

本文来自博客园，作者：飞云~风之谷，转载请注明原文链接：https://www.cnblogs.com/cnscud/p/15103859.html

到此这篇关于MyBatis使用Zookeeper保存数据库的配置,可动态刷新的文章就介绍到这了,更多相关MyBatis使用Zookeeper保存数据库的配置,可动态刷新内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！