我指的是这篇文章，其中我们可以使用 Spring Framework 中的 AbstractRoutingDataSource 来动态更改应用程序使用的数据源。我正在使用 Mybatis (3.3.0) 和 Spring (4.1.6.RELEASE)。如果从主数据库获取数据时发生异常，我想切换到备份数据库。在这个例子中，我使用了 hsql 和 mysql db。
路由数据源：
public class RoutingDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DataSourceContextHolder.getTargetDataSource();
}
}
数据源上下文持有者：
public class DataSourceContextHolder {
private static final ThreadLocal<DataSourceEnum> contextHolder = new ThreadLocal<DataSourceEnum>();
public static void setTargetDataSource(DataSourceEnum targetDataSource) {
contextHolder.set(targetDataSource);
}
public static DataSourceEnum getTargetDataSource() {
return (DataSourceEnum) contextHolder.get();
}
public static void resetDefaultDataSource() {
contextHolder.remove();
}
}
应用数据配置：
@Configuration
@MapperScan(basePackages = "com.sample.mapper")
@ComponentScan("com.sample.config")
@PropertySource(value = {"classpath:app.properties"},
ignoreResourceNotFound = true)
public class ApplicationDataConfig {
@Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
PropertySourcesPlaceholderConfigurer configurer =
new PropertySourcesPlaceholderConfigurer();
return configurer;
}
@Bean
public SqlSessionFactoryBean sqlSessionFactoryBean() throws Exception {
SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
RoutingDataSource routingDataSource = new RoutingDataSource();
routingDataSource.setDefaultTargetDataSource(dataSource1());
Map<Object, Object> targetDataSource = new HashMap<Object, Object>();
targetDataSource.put(DataSourceEnum.HSQL, dataSource1());
targetDataSource.put(DataSourceEnum.BACKUP, dataSource2());
routingDataSource.setTargetDataSources(targetDataSource);
sessionFactory.setDataSource(routingDataSource);
sessionFactory.setTypeAliasesPackage("com.sample.common.domain");
sessionFactory.setMapperLocations(
new PathMatchingResourcePatternResolver()
.getResources("classpath*:com/sample/mapper/**/*.xml"));
return sessionFactory;
}
@Bean
public DataSource dataSource1() {
return new EmbeddedDatabaseBuilder().setType(EmbeddedDatabaseType.HSQL).addScript(
"classpath:database/app-hsqldb-schema.sql").addScript(
"classpath:database/app-hsqldb-datascript.sql").build();
}
@Bean
public DataSource dataSource2() {
PooledDataSourceFactory pooledDataSourceFactory = new PooledDataSourceFactory();
pooledDataSourceFactory.setProperties(jdbcProperties());
return pooledDataSourceFactory.getDataSource();
}
@Bean
protected Properties jdbcProperties() {
//Get the data from properties file
Properties jdbcProperties = new Properties();
jdbcProperties.setProperty("url", datasourceUrl);
jdbcProperties.setProperty("driver", datasourceDriver);
jdbcProperties.setProperty("username", datasourceUsername);
jdbcProperties.setProperty("password", datasourcePassword);
jdbcProperties.setProperty("poolMaximumIdleConnections", maxConnectionPoolSize);
jdbcProperties.setProperty("poolMaximumActiveConnections", minConnectionPoolSize);
return jdbcProperties;
}
}
客户：
@Autowired
private ApplicationMapper appMapper;
public MyObject getObjectById(String Id) {
MyObject myObj = null;
try{
DataSourceContextHolder.setTargetDataSource(DataSourceEnum.HSQL);
myObj = appMapper.getObjectById(Id);
}catch(Throwable e){
DataSourceContextHolder.setTargetDataSource(DataSourceEnum.BACKUP);
myObj = appMapper.getObjectById(Id);
}finally{
DataSourceContextHolder.resetDefaultDataSource();
}
return getObjectDetails(myObj);
}
我收到以下异常
### Error querying database. Cause: java.lang.IllegalArgumentException: DataSource router not initialized
但是，如果我一次只使用一个数据库，我可以让事情正常工作，这意味着数据源配置没有问题。