Spring作为后端的JBPM应用无法解析#{expression}表达式问题排查

I’ve run into this exact problem before—Business Central includes all the necessary components to parse those #{variable} expressions automatically, but when building a custom Spring Boot service with the kjar-service structure, you have to manually ensure the right dependencies and configurations are in place. Here’s how to fix it:

1. Add Critical jBPM Dependencies to Your kjar #

Looking at your kjar pom, you’re missing the core jBPM modules that handle BPMN parsing and human task expression resolution. Add these to your kjar’s <dependencies> section:

<dependency>
    <groupId>org.jbpm</groupId>
    <artifactId>jbpm-bpmn2</artifactId>
    <version>${version.org.kie}</version>
</dependency>
<dependency>
    <groupId>org.jbpm</groupId>
    <artifactId>jbpm-human-task-core</artifactId>
    <version>${version.org.kie}</version>
</dependency>

These dependencies are responsible for processing the BPMN definition and replacing the #{} expressions with actual process variable values when tasks are created.

2. Verify Service-Side Configuration & Dependencies #

Your service uses kie-server-spring-boot-starter, which should include most required components, but let’s make sure expression support isn’t disabled. Add these properties to your Spring Boot application.properties (or yml):

# Enable jBPM expression resolution
jbpm.expression.enabled=true
# Ensure Kie Server uses proper session configuration (adjust credentials as needed)
kie.server.controller.user=kieserver
kie.server.controller.password=kieserver1!

If you still see issues, you can explicitly add the Spring integration module for human tasks (though the starter should include it indirectly):

<dependency>
    <groupId>org.jbpm</groupId>
    <artifactId>jbpm-human-task-spring</artifactId>
    <version>${version.org.kie}</version>
</dependency>

3. Double-Check Process Variable Scope & Assignment #

Make sure your codiceEsito variable is set before the task is created in the process flow, and that it’s in the correct scope (process instance scope, not a local task variable). When starting the process, pass the variable explicitly:

Map<String, Object> processVars = new HashMap<>();
processVars.put("codiceEsito", "01");
kieServices.getRuntimeManager()
           .getRuntimeEngine(EmptyContext.get())
           .getKieSession()
           .startProcess("your-process-definition-id", processVars);

4. Rebuild & Redeploy #

After updating dependencies, rebuild your kjar and restart the Spring service:

# In your kjar directory
mvn clean install -DskipTests

# In your service directory
mvn spring-boot:run

Quick Additional Checks #

• Confirm your BPMN task’s name is exactly EndTask-#{codiceEsito}—no typos like ${} instead of #{}.
• Check your service logs for WARN/ERROR messages related to expression parsing or missing jBPM components; those will point you to any remaining gaps.

Once you’ve gone through these steps, the #{codiceEsito} expression should resolve correctly, and your H2 database will show the task name as EndTask-01 instead of the raw expression.

内容的提问来源于stack exchange，提问作者L_Cleo