hsql+mysql多数据源动态切换
业务背景最近有个需求:需要先启动一个web服务,然后这个服务去部署mysql,redis等相关服务,并且该服务要动态的把mysql和redis在不重启的情况加载进去。项目链接链接: link.
业务背景
最近有个需求:需要先启动一个web服务,然后这个服务去部署mysql,redis等相关服务,并且该服务要动态的把mysql在不重启项目的情况加载进去。
项目思路
项目先使用内存数据库或者内存进行数据暂存(这里我选择了内存数据库hsql),启动先加载hsqldb数据源,然后根据mysql部署情况动态的添加到相应的数据源
框架选型
springboot-2.11+mysql+hsql
1.pom文件(因为是直接贴出来的,有些不需要的请自行忽略)
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
</dependency>
<dependency>
<groupId>com.github.penggle</groupId>
<artifactId>kaptcha</artifactId>
<version>2.3.2</version>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>${mybatis-spring-boot-starter.version}</version>
<exclusions>
<exclusion>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jdbc</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- spring data jpa -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- Swagger -->
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>${io.springfox.version}</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>${io.springfox.version}</version>
</dependency>
<!-- MySQL Connector-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql-connetcor.version}</version>
<!--<scope>runtime</scope>-->
</dependency>
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-core</artifactId>
<version>1.3.2</version>
<scope>compile</scope>
<optional>true</optional>
</dependency>
<!--lombok-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</dependency>
<dependency>
<groupId>commons-httpclient</groupId>
<artifactId>commons-httpclient</artifactId>
<version>${commons-httpclient.version}</version>
</dependency>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>${commons-lang.version}</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
</dependency>
<!-- 内存数据库hsqldb -->
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.70</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.2.1</version>
</dependency>
</dependencies>
首先需要定义一个数据源切换注解,调用时表明使用哪一个数据源
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
DataSourceTypeEnum value() default DataSourceTypeEnum.MYSQL;
}
既然申明了注解,那么我们就需要去拦截并切换到对应的数据源,这时候就申明一个aop进行拦截处理
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import javax.servlet.http.HttpServletRequest;
@Aspect
@Component
public class DataSourceAop {
private static final Logger logger = LoggerFactory.getLogger(DataSourceAop.class);
@Autowired
private HttpServletRequest request;
/**
* 拦截类作用域的注解
* @param dataSource
*/
@Before("@within(dataSource) ")
public void beforeDataSource(DataSource dataSource) {
String value = dataSource.value().getDb();
DataSourceContextHolder.setDataSource(value);
try {
logger.info("当前请求:{},当前使用的数据源为:{}",request.getRequestURI(), value);
}catch (Exception e){
}
}
/**
* 拦截method作用域的注解
* @param dataSource
*/
@Before("@annotation(dataSource) ")
public void beforeDataSourceMethod(JoinPoint joinPoint,DataSource dataSource) {
String value = dataSource.value().getDb();
DataSourceContextHolder.setDataSource(value);
try {
logger.info("当前请求:{},当前使用的数据源为:{}",request.getRequestURI(), value);
}catch (Exception e){
}
}
/**
* 按需在结束之后处理一些业务
* @param dataSource
*/
@After("@within(dataSource) ")
public void afterDataSource(DataSource dataSource) {
// todo something with yourself;
}
@After("@annotation(dataSource) ")
public void afterDataSourceMethod(DataSource dataSource) {
// todo something with yourself;
}
}
细心的朋友应该已经发现这里用到了DataSourceContextHolder,并且设置了对应的数据源,那这个是做什么的呢?我们继续往下看
import java.util.Map;
public class DataSourceContextHolder {
// 存放当前线程使用的数据源类型
private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();
//把当前事物下的连接塞入,用于事物处理
private static ThreadLocal<Map<String, ConnectWarp>> connectionThreadLocal = new ThreadLocal<>();
// 设置数据源
public static void setDataSource(String type){
contextHolder.set(type);
}
// 获取数据源
public static String getDataSource(){
return contextHolder.get();
}
// 清除数据源
public static void clearDataSource(){
contextHolder.remove();
}
// 设置连接
public static void setConnection(Map<String, ConnectWarp> connections){
connectionThreadLocal.set(connections);
}
// 获取连接
public static Map<String, ConnectWarp> getConnection(){
return connectionThreadLocal.get();
}
// 清除连接
public static void clearConnection(){
connectionThreadLocal.remove();
}
通过上面的代码我们发现它好像没做什么业务处理,只是单纯的申明了线程变量,以及基本的赋值和查询,那么数据源真正的切换是如何实现的呢?别急,我们马上接近真相了
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
public class DynamicDataSource extends AbstractRoutingDataSource {
private static Map<Object, Object> dataSourceMap = new HashMap<Object, Object>();
private static DynamicDataSource instance;
private static byte[] lock = new byte[0];
public static DynamicDataSource getInstance() {
if (instance == null) {
synchronized (lock) {
if (instance == null) {
instance = new DynamicDataSource();
}
}
}
return instance;
}
/**
* 重写setTargetDataSources,通过入参targetDataSources进行数据源的添加
* @param targetDataSources
*/
@Override
public void setTargetDataSources(Map<Object, Object> targetDataSources) {
super.setTargetDataSources(targetDataSources);
dataSourceMap.putAll(targetDataSources);
super.afterPropertiesSet();
}
@Override
protected Object determineCurrentLookupKey() {
String dataSource = DataSourceContextHolder.getDataSource();
return dataSource;
}
/**
* 获取到原有的多数据源,并从该数据源基础上添加一个或多个数据源后,通过上面的setTargetDataSources进行加载
*
* @return
*/
public Map<Object, Object> getDataSourceMap() {
return dataSourceMap;
}
/**
* 开启事物的时候,把连接放入 线程中,后续crud 都会拿对应的连接操作
*
* @param key
* @param connection
*/
public void bindConnection(String key, Connection connection) {
Map<String, ConnectWarp> connectionMap = DataSourceContextHolder.getConnection();
if (connectionMap == null) {
connectionMap = new HashMap<>();
}
ConnectWarp connectWarp = new ConnectWarp(connection);
connectionMap.put(key, connectWarp);
DataSourceContextHolder.setConnection(connectionMap);
}
/**
* 提交事物
*
* @throws SQLException
*/
protected void doCommit() throws SQLException {
Map<String, ConnectWarp> stringConnectionMap = DataSourceContextHolder.getConnection();
if (stringConnectionMap == null) {
return;
}
for (String dataSourceName : stringConnectionMap.keySet()) {
ConnectWarp connection = stringConnectionMap.get(dataSourceName);
connection.commit(true);
connection.close(true);
}
DataSourceContextHolder.clearConnection();
}
/**
* 撤销事物
*
* @throws SQLException
*/
protected void rollback() throws SQLException {
Map<String, ConnectWarp> stringConnectionMap = DataSourceContextHolder.getConnection();
if (stringConnectionMap == null) {
return;
}
for (String dataSourceName : stringConnectionMap.keySet()) {
ConnectWarp connection = stringConnectionMap.get(dataSourceName);
connection.rollback();
connection.close(true);
}
DataSourceContextHolder.clearConnection();
}
/**
* 如果 在connectionThreadLocal 中有 说明开启了事物,就从这里面拿
*
* @return
* @throws SQLException
*/
@Override
public Connection getConnection() throws SQLException {
Map<String, ConnectWarp> stringConnectionMap = DataSourceContextHolder.getConnection();
if (stringConnectionMap == null) {
//没开事物 直接走
return determineTargetDataSource().getConnection();
} else {
//开了事物,从当前线程中拿,而且拿到的是 包装过的connect 只有我能关闭O__O "…
String currentName = (String) determineCurrentLookupKey();
return stringConnectionMap.get(currentName);
}
}
}
这个类里面最核心的就是setTargetDataSources和determineCurrentLookupKey两个方法。首先setTargetDataSources重写,保证我们能够动态的添加数据源;然后determineCurrentLookupKey重写,保证我们能够从我们动态添加的数据源里面取出相应的数据源。
到这里呢就差不多快成功了,只差最后一步了,我们来看看这关键的最后一步:添加到spring管理
import com.github.pagehelper.PageInterceptor;
import com.zaxxer.hikari.HikariDataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
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;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
@Configuration
public class DataSourceConfig {
@Autowired
private HsqlConfig hsqlConfig;
@Bean("hsqlDataSource")
@Primary
public DataSource hsqlDataSource() {
HikariDataSource dataSource = new HikariDataSource();
BeanUtils.copyProperties(hsqlConfig, dataSource);
dataSource.setJdbcUrl(hsqlConfig.getJdbcUrl());
return dataSource;
}
@Bean
public DynamicDataSource dataSource(@Qualifier("hsqlDataSource") DataSource hsqlDataSource) {
Map<Object, Object> map = new HashMap<>();
map.put(DataSourceTypeEnum.HSQL.getDb(), hsqlDataSource);
DynamicDataSource dynamicDataSource = DynamicDataSource.getInstance();
dynamicDataSource.setTargetDataSources(map);
return dynamicDataSource;
}
@Bean
public SqlSessionFactory sqlSessionFactory(DynamicDataSource dynamicDataSource) throws Exception {
SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
factoryBean.setDataSource(dynamicDataSource);
factoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));
//分页插件
Interceptor interceptor = new PageInterceptor();
Properties properties = new Properties();
properties.setProperty("helperDialect", "mysql");
properties.setProperty("offsetAsPageNum", "true");
properties.setProperty("rowBoundsWithCount", "true");
properties.setProperty("reasonable", "true");
properties.setProperty("supportMethodsArguments", "true");
interceptor.setProperties(properties);
Interceptor[] plugins = {interceptor};
factoryBean.setPlugins(plugins);
return factoryBean.getObject();
}
@Bean
@Qualifier("transactionManager")
public PlatformTransactionManager transactionManager(DynamicDataSource dynamicDataSource) {
return new DataSourceTransactionManager(dynamicDataSource);
}
}
到这里这个多数据动态添加已经切换就已经OK了,然后有些很细心很细心的朋友发现了,我里面对connect也做了写处理,这个是重写了事务机制,这个我们下期继续分析。
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