Flowable source code comment (XXXIX) task listener

Flowable Source code address ：https://github.com/flowable/flowable-engine

Flowable-6.7.2 Source code comment address ：https://github.com/solojin/flowable-6.7.2-annotated

Package path ：org.flowable.engine.delegate

TaskListener Listen for interface classes for tasks , The implementation class has 4 Kind of ：

• UserTaskIdHandler User tasks ID Processing class

• UserTaskAssignmentHandler User task agent processing class

• ExpressionTaskListener Expression task listener

• DelegateExpressionTaskListener Proxy expression task listener

TaskListener Task listener interface class

package org.flowable.engine.delegate;

/** *  ad locum , For backward compatibility , It is best to use the task listener interface class {@link org.flowable.task.service.delegate.TaskListener}. * * @author Tom Baeyens * @author Joram Barrez */
public interface TaskListener extends org.flowable.task.service.delegate.TaskListener {
    

}

UserTaskIdHandler User tasks ID Processing class

package org.activiti.engine.impl.history.handler;

import org.activiti.engine.impl.context.Context;
import org.activiti.engine.impl.persistence.entity.TaskEntity;
import org.flowable.engine.delegate.TaskListener;
import org.flowable.task.service.delegate.DelegateTask;

/** *  Called when a task is created for a user task activity . Allow tasks to be recorded in historical activities id. * *  Responsible for updating the historical activity table ACT_HI_ACTINST The task ID value  * @author Frederik Heremans */
public class UserTaskIdHandler implements TaskListener {
    

    @Override
    public void notify(DelegateTask task) {
    
        Context.getCommandContext().getHistoryManager()
                .recordTaskId((TaskEntity) task);
    }

}

UserTaskAssignmentHandler User task agent processing class

package org.activiti.engine.impl.history.handler;

import org.activiti.engine.impl.context.Context;
import org.activiti.engine.impl.persistence.entity.TaskEntity;
import org.flowable.engine.delegate.TaskListener;
import org.flowable.task.service.delegate.DelegateTask;

/** *  Responsible for updating the historical activity table ACT_HI_ACTINST Task node owner in , Corresponding to the table ASSIGNMENT_ Field  * * @author Tom Baeyens */
public class UserTaskAssignmentHandler implements TaskListener {
    

    @Override
    public void notify(DelegateTask task) {
    
        Context.getCommandContext().getHistoryManager()
                .recordTaskAssignment((TaskEntity) task);
    }

}

ExpressionTaskListener Expression task listener

package org.flowable.cmmn.engine.impl.listener;

import org.flowable.common.engine.api.delegate.Expression;
import org.flowable.task.service.delegate.DelegateTask;
import org.flowable.task.service.delegate.TaskListener;

/** *  Responsible for scheduling and execution expression Way to create a task listener  * * @author Joram Barrez */
public class ExpressionTaskListener implements TaskListener {
    

    protected Expression expression;

    public ExpressionTaskListener(Expression expression) {
    
        this.expression = expression;
    }

    @Override
    public void notify(DelegateTask delegateTask) {
    
        expression.getValue(delegateTask);
    }

    /** *  Return the expression text of this task listener . */
    public String getExpressionText() {
    
        return expression.getExpressionText();
    }

}

DelegateExpressionTaskListener Proxy expression task listener

package org.flowable.cmmn.engine.impl.listener;

import java.util.List;

import org.flowable.cmmn.engine.impl.util.DelegateExpressionUtil;
import org.flowable.cmmn.model.FieldExtension;
import org.flowable.common.engine.api.FlowableIllegalArgumentException;
import org.flowable.common.engine.api.delegate.Expression;
import org.flowable.task.service.delegate.DelegateTask;
import org.flowable.task.service.delegate.TaskListener;

/** *  Responsible for scheduling and execution delegateExpression Way to create a task listener  * * @author Joram Barrez */
public class DelegateExpressionTaskListener implements TaskListener {
    

    protected Expression expression;
    protected List<FieldExtension> fieldExtensions;

    public DelegateExpressionTaskListener(Expression expression, List<FieldExtension> fieldExtensions) {
    
        this.expression = expression;
        this.fieldExtensions = fieldExtensions;
    }

    @Override
    public void notify(DelegateTask delegateTask) {
    
        Object delegate = DelegateExpressionUtil.resolveDelegateExpression(expression, delegateTask, fieldExtensions);

        if (delegate instanceof TaskListener) {
    
            TaskListener taskListener = (TaskListener) delegate;
            taskListener.notify(delegateTask);
        } else {
    
            //  Delegate expression “+ expression +” It is not resolved to the implementation of task listener 
            throw new FlowableIllegalArgumentException("Delegate expression " + expression + " did not resolve to an implementation of " + TaskListener.class);
        }
    }

    /** *  Return the expression text of this task listener . */
    public String getExpressionText() {
    
        return expression.getExpressionText();
    }

}