MyBatis使用Zookeeper保存数据库的配置可动态刷新的实现代码 MyBatis使用Zookeeper保存数据库的

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@Beanpublic SqlSessionTemplate sqlSessionTemplateMainDataSource(@Qualifier("sqlSessionFactoryMainDataSource") SqlSessionFactory sqlSessionTemplateMainDataSource) throws Exception {//使用注解中配置的Factoryreturn new SqlSessionTemplate(sqlSessionTemplateMainDataSource); }@Primary@Beanpublic 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); }@Overridepublic Connection getConnection() throws SQLException {return pickDataSource().getConnection(); }@Overridepublic Connection getConnection(String username, String password) throws SQLException {return pickDataSource().getConnection(username, password); }@Overridepublic T unwrap(Class iface) throws SQLException {return pickDataSource().unwrap(iface); }@Overridepublic boolean isWrapperFor(Class iface) throws SQLException {return pickDataSource().isWrapperFor(iface); }@Overridepublic PrintWriter getLogWriter() throws SQLException {return pickDataSource().getLogWriter(); }@Overridepublic void setLogWriter(PrintWriter out) throws SQLException {pickDataSource().setLogWriter(out); }@Overridepublic void setLoginTimeout(int seconds) throws SQLException {pickDataSource().setLoginTimeout(seconds); }@Overridepublic int getLoginTimeout() throws SQLException {return pickDataSource().getLoginTimeout(); }@Overridepublic 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 (imxylz@gmail.com) * @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250-500config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048"); //单条语句最大长度默认256，官方推荐2048config.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0config.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, propertiespublic static Map getInstance(final String instanceName) throws Exception {String data = https://www.it610.com/article/ConfigCenter.getInstance().getDataAsString("/xpower/dbn/" + instanceName); if(StringUtils.isEmpty(data)){return null; }data = https://www.it610.com/article/data.trim(); if (data.startsWith("{")) {//as jsonMap 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 propertiesProperties 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
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