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
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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:
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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 */ 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> T unwrap(Class<T> 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.
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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<String, DataSource> instances = new ConcurrentHashMap<>(); private final Set<String> watcherSchema = new HashSet<String>(); 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<String, String> 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<String, String> 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:
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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<String, String> 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<String, String> args) { return args.get("driver-class-name"); } private String getUrl(Map<String, String> 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:
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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<String, String> 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<String, String> swap = Jsons.fromJson(data, Map.class); Map<String, String> 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<String, String> 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:
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/** * 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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