开篇之前，说一句题外话。多数据源和动态数据源的区别。
- 多数据源，一般用于对接多个业务上独立的数据库（可能异构数据库）。
- 动态数据源，一般用于大型应用对数据切分。
配置参考
如何配置多数据源，网上教程一大堆。可参考 SpringBoot+MyBatis多数据源最简解决方案。
问题描述
在实际开发配置中发现，如果要启用Druid的防火墙监控（WallFilter）和统计监控（StatFilter），多个异构数据源就会出错，错误信息如下：
com.alibaba.druid.sql.parser.ParserException: syntax error, error in....跟踪Druid的源码，发现了问题。
// com.alibaba.druid.wall.WallFilter
private WallCheckResult checkInternal(String sql) throws SQLException {
WallCheckResult checkResult = provider.check(sql);
List violations = checkResult.getViolations();
// ... 下面省略了 ...
} 所有的检查sql工作，都在checkInternal方法中完成，而provider对象在执行init初始化之后就再也没有改变了。这也就导致异构数据库的sql检查
StatFilter也是类似问题。
// com.alibaba.druid.filter.stat.StatFilter#createSqlStat(StatementProxy, String)
public JdbcSqlStat createSqlStat(StatementProxy statement, String sql) {
// ...省略
String dbType = this.dbType;
if (dbType == null) {
dbType = dataSource.getDbType();
}
// ...省略//
}解决方案
重写WallFilter
import com.alibaba.druid.filter.FilterChain;
import com.alibaba.druid.proxy.jdbc.CallableStatementProxy;
import com.alibaba.druid.proxy.jdbc.ConnectionProxy;
import com.alibaba.druid.proxy.jdbc.DataSourceProxy;
import com.alibaba.druid.proxy.jdbc.PreparedStatementProxy;
import com.alibaba.druid.util.JdbcUtils;
import com.alibaba.druid.wall.WallConfig;
import com.alibaba.druid.wall.WallFilter;
import com.alibaba.druid.wall.WallProvider;
import com.alibaba.druid.wall.spi.DB2WallProvider;
import com.alibaba.druid.wall.spi.MySqlWallProvider;
import com.alibaba.druid.wall.spi.OracleWallProvider;
import com.alibaba.druid.wall.spi.PGWallProvider;
import com.alibaba.druid.wall.spi.SQLServerWallProvider;
import java.lang.reflect.Field;
import java.sql.SQLException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* 自定义Druid防火墙过滤器
* 使用多类型数据源时，因共用WallProvider解析器，导致判断数据源类型出错
* @author BBF
* @see com.alibaba.druid.wall.WallFilter
*/
public class FrameWallFilter extends WallFilter {
/**
* 用线程安全的ConcurrentHashMap存储WallProvider对象
*/
private final Map providerMap = new ConcurrentHashMap<>(8);
/**
* 获取WallProvider
* @param dataSource 数据源
* @return WallProvider
*/
private WallProvider getProvider(DataSourceProxy dataSource) {
String dbType;
if (dataSource.getDbType() != null) {
dbType = dataSource.getDbType();
} else {
dbType = JdbcUtils.getDbType(dataSource.getRawJdbcUrl(), "");
}
WallProvider provider;
if (JdbcUtils.MYSQL.equals(dbType) || JdbcUtils.MARIADB.equals(dbType) || JdbcUtils.H2.equals(dbType)) {
provider = providerMap.get(JdbcUtils.MYSQL);
if (provider == null) {
provider = new MySqlWallProvider(new WallConfig(MySqlWallProvider.DEFAULT_CONFIG_DIR));
provider.setName(dataSource.getName());
providerMap.put(JdbcUtils.MYSQL, provider);
}
} else if (JdbcUtils.ORACLE.equals(dbType) || JdbcUtils.ALI_ORACLE.equals(dbType)) {
provider = providerMap.get(JdbcUtils.ORACLE);
if (provider == null) {
provider = new OracleWallProvider(new WallConfig(OracleWallProvider.DEFAULT_CONFIG_DIR));
provider.setName(dataSource.getName());
providerMap.put(JdbcUtils.ORACLE, provider);
}
} else if (JdbcUtils.SQL_SERVER.equals(dbType) || JdbcUtils.JTDS.equals(dbType)) {
provider = providerMap.get(JdbcUtils.SQL_SERVER);
if (provider == null) {
provider = new SQLServerWallProvider(new WallConfig(SQLServerWallProvider.DEFAULT_CONFIG_DIR));
provider.setName(dataSource.getName());
providerMap.put(JdbcUtils.SQL_SERVER, provider);
}
} else if (JdbcUtils.POSTGRESQL.equals(dbType) || JdbcUtils.ENTERPRISEDB.equals(dbType)) {
provider = providerMap.get(JdbcUtils.POSTGRESQL);
if (provider == null) {
provider = new PGWallProvider(new WallConfig(PGWallProvider.DEFAULT_CONFIG_DIR));
provider.setName(dataSource.getName());
providerMap.put(JdbcUtils.POSTGRESQL, provider);
}
} else if (JdbcUtils.DB2.equals(dbType)) {
provider = providerMap.get(JdbcUtils.DB2);
if (provider == null) {
provider = new DB2WallProvider(new WallConfig(DB2WallProvider.DEFAULT_CONFIG_DIR));
provider.setName(dataSource.getName());
providerMap.put(JdbcUtils.DB2, provider);
}
} else {
throw new IllegalStateException("dbType not support : " + dbType);
}
return provider;
}
/**
* 利用反射来更新父类私有变量provider
* @param connection ConnectionProxy
*/
private void setProvider(ConnectionProxy connection) {
for (Class cls = this.getClass(); cls != Object.class; cls = cls.getSuperclass()) {
try {
Field field = cls.getDeclaredField("provider");
field.setAccessible(true);
field.set(this, getProvider(connection.getDirectDataSource()));
} catch (Exception e) {
// Field不在当前类定义,继续向上转型
}
}
}
@Override
public PreparedStatementProxy connection_prepareStatement(FilterChain chain,
ConnectionProxy
connection,
String sql) throws SQLException {
this.setProvider(connection);
return super.connection_prepareStatement(chain, connection, sql);
}
@Override
public PreparedStatementProxy connection_prepareStatement(FilterChain chain,
ConnectionProxy connection,
String sql,
int autoGeneratedKeys) throws SQLException {
this.setProvider(connection);
return super.connection_prepareStatement(chain, connection, sql, autoGeneratedKeys);
}
@Override
public PreparedStatementProxy connection_prepareStatement(FilterChain chain,
ConnectionProxy connection,
String sql,
int resultSetType,
int resultSetConcurrency)
throws SQLException {
this.setProvider(connection);
return super.connection_prepareStatement(chain, connection, sql,
resultSetType, resultSetConcurrency);
}
@Override
public PreparedStatementProxy connection_prepareStatement(FilterChain chain,
ConnectionProxy connection,
String sql,
int resultSetType,
int resultSetConcurrency,
int resultSetHoldability) throws SQLException {
this.setProvider(connection);
return super.connection_prepareStatement(chain, connection, sql,
resultSetType, resultSetConcurrency, resultSetHoldability);
}
@Override
public PreparedStatementProxy connection_prepareStatement(FilterChain chain,
ConnectionProxy connection,
String sql,
int[] columnIndexes) throws SQLException {
this.setProvider(connection);
return super.connection_prepareStatement(chain, connection, sql, columnIndexes);
}
@Override
public PreparedStatementProxy connection_prepareStatement(FilterChain chain,
ConnectionProxy connection,
String sql,
String[] columnNames) throws SQLException {
this.setProvider(connection);
return super.connection_prepareStatement(chain, connection, sql, columnNames);
}
@Override
public CallableStatementProxy connection_prepareCall(FilterChain chain,
ConnectionProxy connection,
String sql) throws SQLException {
this.setProvider(connection);
return super.connection_prepareCall(chain, connection, sql);
}
@Override
public CallableStatementProxy connection_prepareCall(FilterChain chain,
ConnectionProxy connection,
String sql,
int resultSetType,
int resultSetConcurrency) throws SQLException {
this.setProvider(connection);
return super.connection_prepareCall(chain, connection, sql,
resultSetType, resultSetConcurrency);
}
@Override
public CallableStatementProxy connection_prepareCall(FilterChain chain,
ConnectionProxy connection,
String sql,
int resultSetType,
int resultSetConcurrency,
int resultSetHoldability) throws SQLException {
this.setProvider(connection);
return super.connection_prepareCall(chain, connection, sql,
resultSetType, resultSetConcurrency, resultSetHoldability);
}
} 重写StatFilter
import com.alibaba.druid.filter.stat.StatFilter;
import com.alibaba.druid.proxy.jdbc.StatementProxy;
import com.alibaba.druid.stat.JdbcSqlStat;
/**
* 自定义Druid统计监控过滤器
* 使用多类型数据源时，因没有及时清空dbType，导致判断数据源类型出错
* @author BBF
* @see com.alibaba.druid.filter.stat.StatFilter#createSqlStat(StatementProxy, String)
*/
public class FrameStatFilter extends StatFilter {
@Override
public JdbcSqlStat createSqlStat(StatementProxy statement, String sql) {
super.setDbType(null);
return super.createSqlStat(statement, sql);
}
}配置过滤器的Bean
如果存在多个同类Bean候选时，被@Primary标志的Bean优先。
另外两个注解@ConfigurationProperties和@ConditionalOnProperty是配置文件的前缀和有特定属性值时生效
/**
* 自定义Druid防火墙过滤器Bean
* @param wallConfig 防火墙过滤器配置Bean
* @return WallFilter
* @see com.alibaba.druid.spring.boot.autoconfigure.stat.DruidFilterConfiguration#wallFilter
*/
@Bean("wallFilter")
@ConfigurationProperties("spring.datasource.druid.filter.wall")
@ConditionalOnProperty(prefix = "spring.datasource.druid.filter.wall", name = {"enabled"})
@Primary
public WallFilter wallFilter(@Qualifier("wallConfig") WallConfig wallConfig) {
WallFilter filter = new FrameWallFilter();
filter.setConfig(wallConfig);
return filter;
}
/**
* 自定义Druid统计监控过滤器Bean
* @return StatFilter
* @see com.alibaba.druid.spring.boot.autoconfigure.stat.DruidFilterConfiguration#statFilter
*/
@Bean("statFilter")
@ConfigurationProperties("spring.datasource.druid.filter.stat")
@ConditionalOnProperty(prefix = "spring.datasource.druid.filter.stat", name = {"enabled"}
)
@Primary
public StatFilter statFilter() {
return new FrameStatFilter();
}附录
数据源配置类
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import com.alibaba.druid.util.JdbcUtils;
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.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import javax.sql.DataSource;
/**
* 配置从数据源
* @author BBF
*/
@Configuration
@MapperScan(basePackages = MysqlDataSourceConfig.PACKAGE,
sqlSessionTemplateRef = MysqlDataSourceConfig.SESSION_NAME)
public class MysqlDataSourceConfig {
/**
* Dao类所在的包
*/
public static final String PACKAGE = "com.bbf.frame.service.dao";
/**
* mapper.xml所在目录
*/
private static final String MAPPER_LOCATION = "classpath:/mapperMysql/*Mapper.xml";
/**
* mybatis的配置文件路径
*/
private static final String CONFIG_LOCATION = "classpath:/config/mybatis-config.xml";
/**
* bean的名称
*/
private static final String DATASOURCE_NAME = "mysqlDataSource";
private static final String FACTORY_NAME = "mysqlSqlSessionFactory";
public static final String SESSION_NAME = "mysqlSqlSessionTemplate";
@Bean(DATASOURCE_NAME)
@ConfigurationProperties("datasource.druid.mysql")
public DataSource dataSourceTwo() {
DruidDataSource ds= DruidDataSourceBuilder.create().build();
ds.setDbType(JdbcUtils.MYSQL);
return ds;
}
/**
* Mybatis的SQL会话工厂
* @param dataSource 数据源
* @return SqlSessionFactory
* @throws Exception 创建SqlSessionFactory发生异常
*/
@Bean(name = FACTORY_NAME)
public SqlSessionFactory sqlSessionFactory(@Qualifier(DATASOURCE_NAME) DataSource dataSource) throws Exception {
final SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource);
ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
sqlSessionFactoryBean.setMapperLocations(resolver.getResources(MAPPER_LOCATION));
sqlSessionFactoryBean.setConfigLocation(resolver.getResource(CONFIG_LOCATION));
return sqlSessionFactoryBean.getObject();
}
@Bean(SESSION_NAME)
public SqlSessionTemplate sqlSessionTemplate(@Qualifier(FACTORY_NAME) SqlSessionFactory sqlSessionFactory) {
return new SqlSessionTemplate(sqlSessionFactory);
}
}配置文件
为了其它数据源配置的相对独立性，单独保存为一个文件mysql.properties。
在入口类上，定义@PropertySource，本文在主数据源之外，又定义了两个数据源。
@SpringBootApplication
@ImportResource(locations = {"classpath:config/conf.xml"})
@PropertySource(encoding = "UTF8", value = {"classpath:config/datasource/sqlserver.properties",
"classpath:config/datasource/mysql.properties"})
public class Application {
//内容略
}############################################
# DataSource - druid Mysql数据源
############################################
# 多数据源，涉及到异构数据库，必须明确指定dbType，否则druid的WallFilter转换SQL出错
# 取值内容可参考 com.alibaba.druid.util.JdbcConstants
datasource.druid.mysql.db-type=mysql
datasource.druid.mysql.driver-class-name=com.mysql.jdbc.Driver
datasource.druid.mysql.url=jdbc:mysql://192.168.1.2:3306/bbf?characterEncoding=UTF-8
datasource.druid.mysql.username=root
datasource.druid.mysql.password=root
# 初始连接数
datasource.druid.mysql.initial-size=5
#最大连接池数量。default=8+
datasource.druid.mysql.max-active=20
# 获取连接时最大等待时间，单位毫秒。
# 配置了maxWait之后，缺省启用公平锁，并发效率会有所下降。
# 如果需要可以通过配置useUnfairLock属性为true使用非公平锁
datasource.druid.mysql.max-wait=60000
# 开启池的prepared statement池功能，PSCache对支持游标的数据库性能提升巨大
# 如果用Oracle, 则把poolPreparedStatements配置为true, mysql 5.5之后建议true
datasource.druid.mysql.pool-prepared-statements=true
# 要启用PSCache，必须配置大于0，当大于0时，poolPreparedStatements自动触发修改为true。
# 在Druid中，会存在Oracle下PSCache占用内存过多的问题，可以把这个数据配置大一些，比如100。默认=-1
datasource.druid.mysql.max-open-prepared-statements=100
# 用来检测连接是否有效的sql，要求是一个查询语句，常用select 'x'。
# 如果validationQuery为null,testOnBorrow,testOnBorrow,testOnReturn,testWhileIdle都不会起作用。这个可以不配置
datasource.druid.mysql.validation-query=SELECT 'V';
# 单位:秒，检测连接是否有效的超时时间。底层调用jdbc Statement对象的void setQueryTimeout(int seconds)方法
# mysql实现的不是很合理，不建议在mysql下配置此参数
datasource.druid.mysql.validation-query-timeout=1000
# 是否在从池中取出连接前进行检验。如果检验失败，则从池中去除连接并尝试取出另一个
# 注意: 设置为true后，validation-query参数必须设置
datasource.druid.mysql.test-on-borrow=false
# 是否在归还连接池前进行检验
# 注意: 设置为true后，validation-query参数必须设置
datasource.druid.mysql.test-on-return=false
# 建议配置为true,不影响性能，并且保证安全性。
# 申请连接的时候检测，如果空闲时间大于timeBetweenEvictionRunsMillis，
# 执行validationQuery检测连接是否有效，validation-query参数必须设置。default=false
datasource.druid.mysql.test-while-idle=true
# 连接池中的minIdle数据以内的连接，空闲时间超过minEvictableIdleTimeMillis，则会执行keepAlive操作。default=false
datasource.druid.mysql.keep-alive=true
#配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 default=1分钟
#有两个含义：
# (1)Destroy线程会检测连接的间隔时间，如果连接空闲时间大于等于minEvictableIdleTimeMillis则关闭物理连接
# (2)testWhileIdle的判断依据，详细看testWhileIdle属性的说明
datasource.druid.mysql.time-between-eviction-runs-millis=60000
#池中的连接保持空闲而不被驱逐的最小时间，单位是毫秒
datasource.druid.mysql.min-evictable-idle-time-millis=100000
datasource.druid.mysql.max-evictable-idle-time-millis=200000
#合并多个DruidDataSource的监控数据
datasource.druid.mysql.use-global-data-source-stat=false事务配置
这个因人而异，我是更喜欢xml方式配置事务。
将多个xml，import到一个xml中，目的是减少复杂度。入口类加入注解@ImportResource(locations = {"classpath:config/conf.xml"})。