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

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MVuUNNThhsMap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250-500

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.

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