工作流activiti-02事物控制、流程引擎创建

使用activiti中有个很重要的问题就是需要保证事物的控制

activiti使用的是mybatis作为orm技术 封装了一系列的操作数据库操作 这也就是大家调用的api 操作的数据库表都是activit自带的数据表 一般情况下使用spring整合

activiti的事物是很强大的 但是往往就不能如愿 因为公司使用的都是自己的框架不能利用spring来整合事物。

通过java程序来控制activiti的事物

activiti的事物依赖于TransactionFactory 在创建流程引擎ProcessEngine来指定事物工厂，其原因分析如下：

创建流程引擎： ProcessEngine processEngine = conf.buildProcessEngine() ;

conf为StandaloneProcessEngineConfiguration的对象其buildProcessEngine方法如下：

public ProcessEngine buildProcessEngine() {
init();
return new ProcessEngineImpl(this);
}

//调用init方法

protected void init() {
initHistoryLevel();
initExpressionManager();
initVariableTypes();
initBeans();
initFormEngines();
initFormTypes();
initScriptingEngines();
initBusinessCalendarManager();
initCommandContextFactory();
initTransactionContextFactory();
initCommandExecutors();
initServices();
initIdGenerator();
initDeployers();
initJobExecutor();
initMailScanner();
initDataSource();
initTransactionFactory();
initSqlSessionFactory();
initSessionFactories();
initJpa();
initDelegateInterceptor();
initEventHandlers();
}
其中初始化了很多信息，可以依次看看源码  其中initTransactionFactory（）方法代码如下：

// myBatis SqlSessionFactory ////////////////////////////////////////////////

protected void initTransactionFactory() {
if (transactionFactory==null) {
if (transactionsExternallyManaged) {
transactionFactory = new ManagedTransactionFactory();
} else {
transactionFactory = new JdbcTransactionFactory();
}
}
}

其中transactionFactory为 protected TransactionFactory transactionFactory; 类中的属性
由代码可知 如果transactionFactory不为空则事物工厂为JdbcTransactionFactory的实例化对象
那么设置StandaloneProcessEngineConfiguration的transactionFactory的值为一JdbcTransactionFactory对象即可

代码如下：创建一个servlet监听器 在容器启动的时候创建一个流程引擎 （需要配置web.xml文件）

/**********************************************************************
* <pre>
* FILE : MyServletListener.java
* CLASS : MyServletListener
*
* AUTHOR : Liaokailin
*
* FUNCTION :
*
*
* Contact: Sina L凯林
*
*======================================================================
* CHANGE HISTORY LOG
*----------------------------------------------------------------------
* MOD. NO.|   DATE   |   NAME  | REASON  | CHANGE REQ.
*----------------------------------------------------------------------
* 		    |2014年1月17日|Liaokailin| Created |
* DESCRIPTION:
* </pre>
***********************************************************************/
package com.infodms.dms.actions;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import org.activiti.engine.ProcessEngine;
import org.activiti.engine.ProcessEngineConfiguration;
import org.activiti.engine.ProcessEngines;
import org.activiti.engine.impl.cfg.StandaloneProcessEngineConfiguration;

import com.infodms.dms.db.DBManager;
import com.infodms.dms.utils.DmsActivitiTransactionFactory;

public class MyServletListener implements ServletContextListener {

@Override
public void contextDestroyed(ServletContextEvent arg0) {
ProcessEngines.destroy();
}

@Override
public void contextInitialized(ServletContextEvent arg0) {
StandaloneProcessEngineConfiguration conf = (StandaloneProcessEngineConfiguration) ProcessEngineConfiguration.createStandaloneProcessEngineConfiguration();
conf.setDataSource(DBManager.getDataSource()).setDatabaseSchemaUpdate("true").setDbHistoryUsed(true) ;
conf.setTransactionFactory(new DmsActivitiTransactionFactory()) ;
ProcessEngine processEngine = conf.buildProcessEngine() ;

}
}

conf.setTransactionFactory(new DmsActivitiTransactionFactory()) ;设置事物

DmsActivitiTransactionFactory代码如下：

/**********************************************************************
* <pre>
* FILE : DmsActivitiTransactionFactory.java
* CLASS : DmsActivitiTransactionFactory
*
* AUTHOR : Liaokailin
*
* FUNCTION :
*
*
* Contact: Sina L凯林
*
*======================================================================
* CHANGE HISTORY LOG
*----------------------------------------------------------------------
* MOD. NO.|   DATE   |   NAME  | REASON  | CHANGE REQ.
*----------------------------------------------------------------------
* 		    |2014年1月21日|Liaokailin| Created |
* DESCRIPTION:
* </pre>
***********************************************************************/
package com.infodms.dms.utils;

import java.sql.Connection;
import java.util.Properties;

import org.apache.ibatis.transaction.Transaction;
import org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory;

import com.infoservice.po3.core.context.DBService;

public class DmsActivitiTransactionFactory extends JdbcTransactionFactory {

@Override
public Transaction newTransaction(Connection conn, boolean autoCommit) {
System.out.println("开启新的事物");
return new DmsActitiviTransaction(conn,autoCommit) ;
//return (Transaction) DBService.getInstance().getTransaction() ;
}

@Override
public void setProperties(Properties props) {
super.setProperties(props);
}

}

DmsActitiviTransaction 代码如下：

/**********************************************************************
* <pre>
* FILE : DmsActitiviTransaction.java
* CLASS : DmsActitiviTransaction
*
* AUTHOR : Liaokailin
*
* FUNCTION :
*
*
* Contact: Sina L凯林
*
*======================================================================
* CHANGE HISTORY LOG
*----------------------------------------------------------------------
* MOD. NO.|   DATE   |   NAME  | REASON  | CHANGE REQ.
*----------------------------------------------------------------------
* 		    |2014年1月21日|Liaokailin| Created |
* DESCRIPTION:
* </pre>
***********************************************************************/
package com.infodms.dms.utils;

import java.sql.Connection;
import java.sql.SQLException;

import org.apache.ibatis.transaction.jdbc.JdbcTransaction;

import com.infodms.dms.db.DBManager;
import com.infoservice.po3.core.context.DBService;

public class DmsActitiviTransaction extends JdbcTransaction {
private static Connection conn = null ;
public DmsActitiviTransaction(Connection connection,
boolean desiredAutoCommit) {
//connection.setAutoCommit(desiredAutoCommit);
super(connection, desiredAutoCommit);
try {
connection.setAutoCommit(desiredAutoCommit);
} catch (SQLException e) {
e.printStackTrace();
}

}

@Override
public Connection getConnection() {
/*DBService d = DBService.getInstance() ;
d.loadConf("/DataAccessContext.xml");
return d.getConnection() ;*/
//	 return DBService.getInstance().getConnection() ;
try {
if(conn==null){
synchronized (DmsActitiviTransaction.class) {
conn = DBManager.getConnection() ;
}
}
return conn ;
} catch (Exception e) {
System.out.println("获取链接失败："+e);
return null ;
}
}

@Override
public void close() throws SQLException {
/*	if(conn!=null&&!conn.isClosed()){
conn.close();
}*/
System.out.println("activit:close()");
}

@Override
public void commit() throws SQLException {
/*if(conn!=null&&!conn.isClosed()){
conn.commit();
}*/
System.out.println("activit:commit()");
}

@Override
protected void resetAutoCommit() {
System.out.println("resetAutoCommit()");
/*try {
if (conn != null && !conn.isClosed()) {
conn.setAutoCommit(false);
}
} catch (SQLException e) {
e.printStackTrace();

}*/
}

@Override
public void rollback() throws SQLException {
/*if(conn!=null&&!conn.isClosed()){
conn.rollback();
}*/
System.out.println("activit:rollback()");
}

@Override
protected void setDesiredAutoCommit(boolean arg0) {
System.out.println("setDesiredAutoCommit:"+arg0);
}

}

其中DBManager

/**********************************************************************
* <pre>
* FILE : DBManager.java
* CLASS : DBManager
*
* AUTHOR : Liaokailin
*
* FUNCTION :
*
*
* Contact: Sina L凯林
*
*======================================================================
* CHANGE HISTORY LOG
*----------------------------------------------------------------------
* MOD. NO.|   DATE   |   NAME  | REASON  | CHANGE REQ.
*----------------------------------------------------------------------
* 		    |2014年1月22日|Liaokailin| Created |
* DESCRIPTION:
* </pre>
***********************************************************************/
package com.infodms.dms.db;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

import com.infoservice.po3.core.context.DBInfo;

public class DBManager {
public static DataSource dataSource = null  ;
public static Connection conn = null ;
public static DataSource getDataSource(){
if(dataSource==null){
synchronized (DBManager.class) {
Resource resource = new ClassPathResource("/DataAccessContext.xml");
BeanFactory springBeanFactory = new XmlBeanFactory(resource);
DBInfo dbInfo = ((DBInfo)springBeanFactory.getBean("DBInfo"));
dataSource = (DataSource)springBeanFactory.getBean(dbInfo.getDefDataSource());
System.out.println("获取数据源");
}
}else{
System.out.println("默认数据源调用");
}

return dataSource ;
}

public static Connection getConnection() throws SQLException{
if(conn!=null&&!conn.isClosed()){
System.out.println("获取默认连接");

}else{
synchronized (DBManager.class) {
System.out.println("获取连接");
conn = getDataSource().getConnection() ;
}
}
return conn ;
}

public static void startTransaction(Connection connection) throws SQLException {
System.out.println("开启事物");
connection.setAutoCommit(false);
}

public static void endTransaction(Connection connection) throws SQLException{
System.out.println("提交事物 ");
connection.commit();
connection.setAutoCommit(true);
}

public static void rollBack(Connection connection) throws SQLException{
System.out.println("回滚事物");
connection.rollback();
}
}

调用的使用DBManager就ok了