【⼩笔记】Activiti扩展数据库⽀持类型
场景
项⽬需要使⽤GaussDB，Activiti默认⽀持的数据库中不包含GaussDB，需要对其进⾏扩展。
分析
在其源码org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl.getDefaultDatabaseTypeMappings()中，写明了⽀持的数据库的类型：h2、hsql、mysql、oracle、postgres、mssql、db2并在初始化时进⾏了初始化：
protected static Properties databaseTypeMappings = getDefaultDatabaseTypeMappings();public void initDatabaseType() { ...
省略内容 ...}
如果获取到的数据库类型不在⽀持列表中，则会抛错：
connection = this.dataSource.getConnection();
DatabaseMetaData databaseMetaData = connection.getMetaData();
String databaseProductName = databaseMetaData.getDatabaseProductName();this.databaseType = databaseTypeMappings.getProperty(databaseProductName); if (this.databaseType == null) {
throw new ActivitiException(\"couldn't deduct database type from database product name '\" + databaseProductName + \"'\"); }
查看它的实现类，发现有个Spring实现的：
所以继承这个SpringProcesEnineConfiguration，重写⼀下initDatabaseType()，将其注⼊为Bean，即可进⾏扩展。
实现
重写initDatabaseType()：
public class SpringProcessEngineConfigurationWithGauss extends SpringProcessEngineConfiguration { private static Logger log = LoggerFactory.getLogger(SpringProcessEngineConfigurationWithGauss.class); private static Properties databaseTypeMappings = getDefaultDatabaseTypeMappings(); public static Properties getDefaultDatabaseTypeMappings() { Properties databaseTypeMappings = new Properties(); ...
省略其他 ...
databaseTypeMappings.setProperty(\"Zenith\ return databaseTypeMappings; }
@Override
public void initDatabaseType() { Connection connection = null;
try {
connection = this.dataSource.getConnection();
DatabaseMetaData databaseMetaData = connection.getMetaData();
String databaseProductName = databaseMetaData.getDatabaseProductName(); log.debug(\"database product name: '{}'\
this.databaseType = databaseTypeMappings.getProperty(databaseProductName); if (this.databaseType == null) {
throw new ActivitiException(\"couldn't deduct database type from database product name '\" + databaseProductName + \"'\"); }
log.debug(\"using database type: {}\ if (\"mssql\".equals(this.databaseType)) {
this.maxNrOfStatementsInBulkInsert = this.DEFAULT_MAX_NR_OF_STATEMENTS_BULK_INSERT_SQL_SERVER; }
} catch (SQLException var12) {
log.error(\"Exception while initializing Database connection\ } finally { try {
if (connection != null) { connection.close(); }
} catch (SQLException var11) {
log.error(\"Exception while closing the Database connection\ } } }}
将其注⼊：
@Bean
public SpringProcessEngineConfigurationWithGauss processEngineConfiguration() {
SpringProcessEngineConfigurationWithGauss configuration = new SpringProcessEngineConfigurationWithGauss(); ...
省略其他配置 ...
return configuration; }
其次需要在activiti的包⾥新增⼀个⽂件：
org\\activiti\\db\\properties\\下新增Zenith.properties配置⽂件，主要作⽤是为不同数据库配置分页语法，GuassDB是⽀持类似Mysql的分页的，所以直接使⽤Mysql的即可。内容如下：limitAfter=LIMIT #{maxResults} OFFSET #{firstResult}