Display the JBPM flowchart on the JSP page

To display the JBPM flowchart on the JSP page, download the jbpm-starters-kit-3.1.x toolkit first. There is a. java file in the package,

\ Jbpm.3 \ src \ java. webapp \ org \ jbpm \ webapp \ tag \ ProcessImageTag. java with his \ WEB-INF \ jbpm. tld, There are files

\ Jbpm.3 \ src \ java. webapp \ org \ jbpm \ webapp \ servlet \ ProcessImageServlet. java. In the JBPM example, these three files are used together to display the JBPM flowchart.

To make the two files work, you must configure them in web. xml. configuration method:

 
 

  
  
<!-- jBPM FileServlet -->   
  
  
<servlet>   
  
  
    <servlet-name>ProcessImageServlet</servlet-name>   
  
  
    <servlet-class>org.jbpm.webapp.servlet.ProcessImageServlet</servlet-class>   
  
  
</servlet>   
  
  
<servlet-mapping>   
  
  
    <servlet-name>ProcessImageServlet</servlet-name>   
  
  
    <url-pattern>/processimage</url-pattern>   
  
  
</servlet-mapping>   
 
 

On the page, use <jbpm: processimage task = "$ {taskBean. taskInstanceId}"/> to display the flowchart at the current position.

Problems that may occur in the actual environment and necessary modifications

Question 1

If you use spring-integrated jbpm, The JbpmContext method in the two classes will fail.

JbpmContext jbpmContext = JbpmContext. getCurrentJbpmContext (); // This will cause problems.

Modify:

1. In the private void initialize () method of ProcessImageTag. java.

 
 

  
  
WebApplicationContext wac = WebApplicationContextUtils.
getRequiredWebApplicationContext(pageContext.getServletContext());   
  
  
      JbpmTemplate jbpmTemplate = (JbpmTemplate) wac.getBean("jbpmTemplate");   
  
  
      jbpmTemplate.execute(new JbpmCallback() {   
  
  
          public Object doInJbpm(JbpmContext context) {   
  
  
              if (taskInstanceId > 0) {   
  
  
                  TaskInstance taskInstance = context.getTaskMgmtSession().loadTaskInstance(taskInstanceId);   
  
  
                  currentToken = taskInstance.getToken();   
  
  
              }   
  
  
              else   
  
  
              {   
  
  
                  if (tokenInstanceId > 0)   
  
  
                      currentToken = context.getGraphSession().loadToken(tokenInstanceId);   
  
  
              }   
  
  
              return null;   
  
  
          }   
  
  
      });   
 
 

 
 

  
  

public class ProcessImageServlet extends HttpServlet {   
  
  
    private static final long serialVersionUID = 1L;   
  
  
    private ProcessDefinition processDefinition;   
  
  
    private byte[] bytes;   
  
  
 
  
  
    protected void doGet(HttpServletRequest request, 
HttpServletResponse response) throws ServletException, IOException {   
  
  
        final long processDefinitionId = Long.parseLong( request.getParameter( "definitionId" ) );   
  
  
 
  
  
        WebApplicationContext wac = WebApplicationContextUtils.
getRequiredWebApplicationContext(request.getSession().getServletContext());   
  
  
        JbpmTemplate jbpmTemplate = (JbpmTemplate) wac.getBean("jbpmTemplate");   
  
  
        jbpmTemplate.execute(new JbpmCallback() {   
  
  
            public Object doInJbpm(JbpmContext context) {   
  
  
                processDefinition = context.getGraphSession().loadProcessDefinition(processDefinitionId);   
  
  
                bytes = processDefinition.getFileDefinition().getBytes("processimage.jpg");   
  
  
                return null;   
  
  
            }   
  
  
        });   
  
  
 
  
  
        OutputStream out = response.getOutputStream();   
  
  
        out.write(bytes);   
  
  
        out.flush();   
  
  
    }   
  
  
}   
 
 

Question 2

If your process uses Chinese characters and the database character set is UTF-8, the correct UTF-8 content in the database may also be garbled. For example, gpd. xml in my database

Error class: ProcessImageTag. java

Error row: result [0] = Integer. valueOf (node. attribute ("x"). getValue ());

If this is an nullpoint error, it is because the characters in the context Element root are garbled.

Modify:

Original code: Element rootDiagramElement = incluenthelper. parseText (new String (gpdBytes). getRootElement ();

After modification: Element rootDiagramElement = incluenthelper. parseText (new String (gpdBytes, "UTF-8"). getRootElement ();

Note: <jbpm: processimage task = "$ {taskBean. taskInstanceId}"/> displays images based on the current path. Style = "background-image: url (processimage? DefinitionId = 1) ", that is, when the page is: http: // localhost/jbpm/workflow/showTaskInstance. in jsp, the URL of the access flowchart is http: // localhost/jbpm/workflow/processimage? DefinitionId = 1. The address is incorrect. The actual address is: http: // localhost/jbpm/processimage? DefinitionId = 1. to display the information correctly, modify ProcessImageTag. java.

Original code: background-image: url ("+ imageLink + ");

After modification: background-image: url ("+ (HttpServletRequest) pageContext. getRequest (). getContextPath () +"/"+ imageLink + ");

The JBPM flowchart is displayed successfully.

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