核心關鍵點: 封裝一個DataSource, 重寫 getConnection 就可以實現

我們一步一步來看.

環境: Spring Cloud + MyBatis

MyBatis常規方式下配置數據源: 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 多數據源配置: 主數據源. * * @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 { //常規配置: 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數據源, 連接mainDataSource庫factoryBean.setDataSource(mainDataSource);//下邊兩句僅僅用于*.xml文件，如果整個持久層操作不需要使用到xml文件的話（只用注解就可以搞定），則不加//指定entity和mapper xml的路徑//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Factoryreturn new SqlSessionTemplate(sqlSessionTemplateMainDataSource); } @Primary @Bean public PlatformTransactionManager mainTransactionManager(@Qualifier('mainDataSource') DataSource prodDataSource) {return new DataSourceTransactionManager(prodDataSource); }}

這里面獲取數據源的關鍵函數是 mainDataSource, 我們自己來實現就好了:

因為這個是一次性的工作, 所以我們無法修改DataSource的指向, 只能在DataSource內部做文章, 所以我們需要自己實現一個DataSource.

其中的步驟比較多, 我們來看看最終結果:

最終的DataSourceWrapper

它完全封裝了一個DataSource, 自己并沒有任何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, 為了方便動態創建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> 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

支持多個數據源的暫存池, 可以根據name獲取不同的數據庫DataSource實例:

這個類負責創建DataSource, 保存在Map里. 并且能監聽Zookeeper的變化, 一旦偵聽到變化, 就close現有的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. * * 根據名字存放多個數據庫的DataSource, 并且會監聽Zookeeper配置, 動態重建. * * @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; }}

真正創建DataSource的代碼:

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: 可以根據參數里面的類型來使用不同的庫創建DataSource, 例如Druid. (默認為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'); //是否自定義配置，為true時下面兩個參數才生效config.addDataSourceProperty('prepStmtCacheSize', maximumPoolSize); //連接池大小默認25，官方推薦250-500config.addDataSourceProperty('prepStmtCacheSqlLimit', '2048'); //單條語句最大長度默認256，官方推薦2048config.addDataSourceProperty('useServerPrepStmts', 'true'); //新版本MySQL支持服務器端準備，開啟能夠得到顯著性能提升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);//最小閑置連接數，默認為0config.setMaxLifetime(600000);//最大生存時間config.setConnectionTimeout(30000);//超時時間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'); }}

為了方便讀取Zookeeper節點, 還有個SchemeNodeHelper:

支持兩種配置文件的方式 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;/** * 從Zookeeper的 /xpower/dbn節點下讀取數據庫配置. * 內容支持兩種格式: 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); //支持兩種格式: 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); }}

實際應用

最后在MyBatis項目中, 替換原有MainDataSource代碼為:

/** * 添加@Primary注解，設置默認數據源，事務管理器. * 此處使用了一個可以動態重建的DataSource, 如果Zookeeper配置改變,會動態重建. */ @Primary @Bean(name = 'mainDataSource') public DataSource mainDataSource() throws Exception {return SimpleDBNDataSourceFactory.getInstance().getDataSource('cavedemo'); }

運行項目, 發現可以連上數據庫, 并且不重啟項目的情況下, 動態修改數據庫配置, 能自動重連.

項目代碼:

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

其中用到的 ConfigCenter 也在這個項目里, 也可以自己實現, 就可以脫離本項目了.

本文來自博客園，作者：飛云~風之谷，轉載請注明原文鏈接：https://www.cnblogs.com/cnscud/p/15103859.html

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