JBPM3中文用户手册——第三章：教程(2)

3.2    数据库示例

Jbpm的一个基本特性，是能够将处于等待状态的流程执行，持久到数据库。下面的这个例子，展示了如何保存流程实例到jbpm数据库中。同时，这个例子也建议可能出现的场景，并为不同的用户代码片段，创建了单独的方法。例如，在一个Web应用中启动一个流程，并持久到数据中的代码片段；然后，用一个消息驱动Bean，从数据库加载这个流程实例，并恢复执行。

 

jBPM持久相关的更多信息，参见7.持久。

 

public class HelloWorldDbTest extends TestCase {     static JbpmConfiguration jbpmConfiguration = null;     static {     // An example configuration file such as this can be found in     // 'src/config.files'.  Typically the configuration information is in the     // resource file 'jbpm.cfg.xml', but here we pass in the configuration     // information as an XML string.         // First we create a JbpmConfiguration statically.  One JbpmConfiguration     // can be used for all threads in the system, that is why we can safely     // make it static.       jbpmConfiguration = JbpmConfiguration.parseXmlString(       "<jbpm-configuration>" +             // A jbpm-context mechanism separates the jbpm core       // engine from the services that jbpm uses from       // the environment.               "  <jbpm-context>" +       "    <service name='persistence' " +       "             factory='org.jbpm.persistence.db.DbPersistenceServiceFactory' />" +       "  </jbpm-context>" +             // Also all the resource files that are used by jbpm are       // referenced from the jbpm.cfg.xml             "  <string name='resource.hibernate.cfg.xml' " +       "          value='hibernate.cfg.xml' />" +       "  <string name='resource.business.calendar' " +       "          value='org/jbpm/calendar/jbpm.business.calendar.properties' />" +       "  <string name='resource.default.modules' " +       "          value='org/jbpm/graph/def/jbpm.default.modules.properties' />" +       "  <string name='resource.converter' " +       "          value='org/jbpm/db/hibernate/jbpm.converter.properties' />" +       "  <string name='resource.action.types' " +       "          value='org/jbpm/graph/action/action.types.xml' />" +       "  <string name='resource.node.types' " +       "          value='org/jbpm/graph/node/node.types.xml' />" +       "  <string name='resource.varmapping' " +       "          value='org/jbpm/context/exe/jbpm.varmapping.xml' />" +       "</jbpm-configuration>"     );   }     public void setUp() {     jbpmConfiguration.createSchema();   }      public void tearDown() {     jbpmConfiguration.dropSchema();   }     public void testSimplePersistence() {     // Between the 3 method calls below, all data is passed via the     // database.  Here, in this unit test, these 3 methods are executed     // right after each other because we want to test a complete process     // scenario.  But in reality, these methods represent different     // requests to a server.         // Since we start with a clean, empty in-memory database, we have to     // deploy the process first.  In reality, this is done once by the     // process developer.     deployProcessDefinition();       // Suppose we want to start a process instance (=process execution)     // when a user submits a form in a web application...     processInstanceIsCreatedWhenUserSubmitsWebappForm();       // Then, later, upon the arrival of an asynchronous message the     // execution must continue.     theProcessInstanceContinuesWhenAnAsyncMessageIsReceived();   }     public void deployProcessDefinition() {     // This test shows a process definition and one execution     // of the process definition.  The process definition has     // 3 nodes: an unnamed start-state, a state 's' and an     // end-state named 'end'.     ProcessDefinition processDefinition = ProcessDefinition.parseXmlString(       "<process-definition name='hello world'>" +       "  <start-state name='start'>" +       "    <transition to='s' />" +       "  </start-state>" +       "  <state name='s'>" +       "    <transition to='end' />" +       "  </state>" +       "  <end-state name='end' />" +       "</process-definition>"     );       // Lookup the pojo persistence context-builder that is configured above     JbpmContext jbpmContext = jbpmConfiguration.createJbpmContext();     try {       // Deploy the process definition in the database       jbpmContext.deployProcessDefinition(processDefinition);       } finally {       // Tear down the pojo persistence context.       // This includes flush the SQL for inserting the process definition        // to the database.       jbpmContext.close();     }   }     public void processInstanceIsCreatedWhenUserSubmitsWebappForm() {     // The code in this method could be inside a struts-action     // or a JSF managed bean.       // Lookup the pojo persistence context-builder that is configured above     JbpmContext jbpmContext = jbpmConfiguration.createJbpmContext();     try {         GraphSession graphSession = jbpmContext.getGraphSession();             ProcessDefinition processDefinition =           graphSession.findLatestProcessDefinition("hello world");           // With the processDefinition that we retrieved from the database, we       // can create an execution of the process definition just like in the       // hello world example (which was without persistence).       ProcessInstance processInstance =           new ProcessInstance(processDefinition);             Token token = processInstance.getRootToken();       assertEquals("start", token.getNode().getName());       // Let's start the process execution       token.signal();       // Now the process is in the state 's'.       assertEquals("s", token.getNode().getName());             // Now the processInstance is saved in the database.  So the       // current state of the execution of the process is stored in the       // database.        jbpmContext.save(processInstance);       // The method below will get the process instance back out       // of the database and resume execution by providing another       // external signal.       } finally {       // Tear down the pojo persistence context.       jbpmContext.close();     }   }     public void theProcessInstanceContinuesWhenAnAsyncMessageIsReceived() {     // The code in this method could be the content of a message driven bean.       // Lookup the pojo persistence context-builder that is configured above     JbpmContext jbpmContext = jbpmConfiguration.createJbpmContext();     try {         GraphSession graphSession = jbpmContext.getGraphSession();       // First, we need to get the process instance back out of the database.       // There are several options to know what process instance we are dealing       // with here.  The easiest in this simple test case is just to look for       // the full list of process instances.  That should give us only one       // result.  So let's look up the process definition.             ProcessDefinition processDefinition =           graphSession.findLatestProcessDefinition("hello world");         // Now, we search for all process instances of this process definition.       List processInstances =           graphSession.findProcessInstances(processDefinition.getId());             // Because we know that in the context of this unit test, there is       // only one execution.  In real life, the processInstanceId can be       // extracted from the content of the message that arrived or from       // the user making a choice.       ProcessInstance processInstance =           (ProcessInstance) processInstances.get(0);             // Now we can continue the execution.  Note that the processInstance       // delegates signals to the main path of execution (=the root token).       processInstance.signal();         // After this signal, we know the process execution should have       // arrived in the end-state.       assertTrue(processInstance.hasEnded());             // Now we can update the state of the execution in the database       jbpmContext.save(processInstance);       } finally {       // Tear down the pojo persistence context.       jbpmContext.close();     }   } }