WWF3动态修改工作流<第九篇>

一、动态添加或移除工作流活动

　　首先添加一个顺序的空白工作流。

　　

　　然后添加一个Winform程序，界面如下：

　　

　　代码如下：

namespace WinForm
{
    public partial class Form1 : Form
    {
        private WorkflowRuntime workflowRuntime = null;
        private WorkflowInstance workflowInstance = null;
        private WorkflowChanges wfchange = null;

        public Form1()
        {
            InitializeComponent();
            workflowRuntime = new WorkflowRuntime();
            workflowRuntime.StartRuntime();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Type type = typeof(WorkflowConsoleApplication1.Workflow1);
            workflowInstance = workflowRuntime.CreateWorkflow(type);
            Activity Act = workflowInstance.GetWorkflowDefinition();
            wfchange = new WorkflowChanges(Act);

            CodeActivity code1 = new CodeActivity("codeactivity1");
            code1.ExecuteCode += delegate(object s, EventArgs ea)
            {
                MessageBox.Show("工作流被调用!");
            };
            wfchange.TransientWorkflow.Activities.Insert(0, code1);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            workflowInstance.ApplyWorkflowChanges(wfchange);
            workflowInstance.Start();
        }
    }
}

　　效果如下：

　　

二、动态添加或移除容器活动

　　向工作流的容器类型复合活动中动态添加一个子活动。

　　添加一个Sequence容器，然后通过代码向其内部动态添加一个Code类型的子活动。

　　

　　添加一个Winform程序，界面不变：

namespace WinForm
{
    public partial class Form1 : Form
    {
        private WorkflowRuntime workflowRuntime = null;
        private WorkflowInstance workflowInstance = null;
        private WorkflowChanges wfchange = null;

        public Form1()
        {
            InitializeComponent();
            workflowRuntime = new WorkflowRuntime();
            workflowRuntime.StartRuntime();
        }

        //添加一个工作流
        private void button1_Click(object sender, EventArgs e)
        {
            Type type = typeof(WorkflowConsoleApplication1.Workflow1);
            workflowInstance = workflowRuntime.CreateWorkflow(type);
            Activity Act = workflowInstance.GetWorkflowDefinition();
            wfchange = new WorkflowChanges(Act);

            //创建一个Code活动
            CodeActivity code1 = new CodeActivity("codeactivity1");
            code1.ExecuteCode += delegate(object s, EventArgs ea)
            {
                MessageBox.Show("sequenceActivity里的Code工作流被调用!");
            };

            //添加工作流到容器中
            SequenceActivity seq = (SequenceActivity)wfchange.TransientWorkflow.Activities["sequenceActivity1"];
            seq.Activities.Add(code1);
        }

        //移除一个工作流
        private void button3_Click(object sender, EventArgs e)
        {
            Activity Code1 = wfchange.TransientWorkflow.Activities["codeactivity1"];
            SequenceActivity seq = (SequenceActivity)wfchange.TransientWorkflow.Activities["sequenceActivity1"];
            seq.Activities.RemoveAt(0);
        }

        //执行
        private void button2_Click(object sender, EventArgs e)
        {
            workflowInstance.ApplyWorkflowChanges(wfchange);
            workflowInstance.Start();
        }
    }
}

　　改动的部分就是红色部分代码，添加删除一个活动一样是Add、Remove。

三、动态修改判断条件

　　在WWF提供的各种活动空间中，像IfElse和While这两种基于规则模式的活动是需要设置其逻辑判断条件的。该判断条件分为两种类型，一种是"Code Condition"，利用程序代码来定义其逻辑的判断条件，另外一种是"Declarative Rule Condition"。

　　首先建立一个顺序类型的工作流项目，然后添加一个IfElse活动到该工作流设计界面，将IfElse活动空间的两条分支分别命名为"IfBranch"和"ElseBranch"。每条分支添加一个Code活动控件。工作流界面如下：

　　

　　将默认的判断条件设置为如下：

　　

　　工作流代码如下：

    public sealed partial class Workflow1 : SequentialWorkflowActivity
    {
        public int condition;
        public int Condition
        {
            get { return condition; }
            set { condition = value; }
        }

        public Workflow1()
        {
            InitializeComponent();
        }

        private void Code1(object sender, EventArgs e)
        {
            MessageBox.Show("If分支被执行!");
        }

        private void Code2(object sender, EventArgs e)
        {
            MessageBox.Show("Else分支被执行!");
        }
    }

　　创建一个Winform程序，界面如下：

　　

　　代码如下：

namespace WinForm
{
    public partial class Form1 : Form
    {
        private WorkflowRuntime workflowruntime;
        private WorkflowInstance workflowinstance;

        public Form1()
        {
            InitializeComponent();
            workflowruntime = new WorkflowRuntime();
            workflowruntime.StartRuntime();
        }

        //添加一个工作流
        private void button1_Click(object sender, EventArgs e)
        {
            Dictionary<string, object> parameters = new Dictionary<string, object>();
            parameters.Add("Condition", Convert.ToInt32(this.textBox2.Text));
            Type wftype = typeof(WorkflowConsoleApplication1.Workflow1);
            workflowinstance = workflowruntime.CreateWorkflow(wftype, parameters);
            //WWF对所有运行中的工作流都可以通过"WorkflowChanges"对象来实现修改
            //GetWorkflowDefinition得到工作流活动的集合
            WorkflowChanges workflowchanges = new WorkflowChanges(workflowinstance.GetWorkflowDefinition());
            //将工作流所有的活动进行克隆，克隆出来的对象保存在comactivity中
            CompositeActivity comactivity = workflowchanges.TransientWorkflow;
            //RunleDefinitions类专门用于对".rules"文件进行操作
            RuleDefinitions ruleDefinitions = (RuleDefinitions)comactivity.GetValue(RuleDefinitions.RuleDefinitionsProperty);
            //获取所有的逻辑判断集合
            RuleConditionCollection conditions = ruleDefinitions.Conditions;
            //从Condition对象中获取具体的"Condition1"逻辑判断的信息，"Condition1"以"Declarative Rule Condition"方式定义判断条件的名称
            RuleExpressionCondition condition1 = (RuleExpressionCondition)conditions["Condition1"];
            //对原工作流的condition1逻辑判断条件进行修改
            (condition1.Expression as CodeBinaryOperatorExpression).Right = new CodePrimitiveExpression(Convert.ToInt32(this.textBox1.Text));
            //将修改后的信息应用回工作流实例
            workflowinstance.ApplyWorkflowChanges(workflowchanges);
            //重新启动工作流
            workflowinstance.Start();
        }
    }
}

　　运行效果如下：

　　 

　　留意到判断条件已经完全改为为Winform中的判断条件。

四、动态添加StateActivity活动

　　在状态机工作流中同样可以动态加载或修改原有的业务流程。

　　首先定义一个接口如下：

    [ExternalDataExchange]
    public interface IClass
    {
        //入党申请
        event EventHandler<ExternalDataEventArgs> AdmittedIntoParty;
        //介绍人意见
        event EventHandler<ExternalDataEventArgs> SponsorCommit;
        //党委会审批
        event EventHandler<ExternalDataEventArgs> PCApproved;
    }

　　新建一个状态机工作流如下：

　　

　　前两个EventDriven里面添加两个HandleExternalEvent，并绑定刚刚定义的接口里的事件。

　　

　　新建一个Winform程序如下：

　　

　　从上至下分别是button1、2、3、4。

　　代码如下：

namespace WinForm
{
    public partial class Form1 : Form, ClassLibrary1.IClass
    {
        private WorkflowRuntime workflowruntime;
        private WorkflowInstance workflowinstance;
        private ExternalDataExchangeService exterserv;

        public event EventHandler<ExternalDataEventArgs> AdmittedIntoParty;
        public event EventHandler<ExternalDataEventArgs> SponsorCommit;
        public event EventHandler<ExternalDataEventArgs> PCApproved;

        public Form1()
        {
            InitializeComponent();

            workflowruntime = new WorkflowRuntime();
            exterserv = new ExternalDataExchangeService();

            workflowruntime.AddService(exterserv);
            exterserv.AddService(this);

            workflowruntime.StartRuntime();

            Type wftype = typeof(WorkflowConsoleApplication1.Workflow1);
            workflowinstance = workflowruntime.CreateWorkflow(wftype);
            workflowinstance.Start();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            SetStateComboBox();
        }

        private void SetStateComboBox()
        {
            comboBox1.Items.Clear();

            StateMachineWorkflowInstance StateMachineInstance = new StateMachineWorkflowInstance(workflowruntime, workflowinstance.InstanceId);

            ReadOnlyCollection<StateActivity> states = StateMachineInstance.States;

            foreach (StateActivity allState in states)
            {
                this.comboBox1.Items.Add(allState.Name);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            AdmittedIntoParty(null, new ExternalDataEventArgs(workflowinstance.InstanceId));
            this.button1.Enabled = false;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Activity root = workflowinstance.GetWorkflowDefinition();
            WorkflowChanges changes = new WorkflowChanges(root);

            //创建一个状态活动
            StateActivity sponsorsubmit = new StateActivity();
            sponsorsubmit.Name = "介绍人提交意见";

            //创建一个EventDrivenActivity
            EventDrivenActivity sponsoreven = new EventDrivenActivity();
            sponsoreven.Name = "SponsorEvent";
            //向状态活动中添加EventDrivenActivity
            sponsorsubmit.Activities.Add(sponsoreven);

            //创建一个HandleExternalEventActivity
            HandleExternalEventActivity sponsorHandle = new HandleExternalEventActivity();
            sponsorHandle.Name = "SponsorHandle";
            sponsorHandle.InterfaceType = typeof(ClassLibrary1.IClass);
            sponsorHandle.EventName = "SponsorCommit";
            //sponsorHandle.Invoked +=new EventHandler<ExternalDataEventArgs>(sponsorHandle_Invoked); 
            //向EventDrivenActivity中添加HandleExternalEventActivity活动
            sponsoreven.Activities.Add(sponsorHandle);

            //向EventDrivenActivity中添加SetStateActivity活动
            SetStateActivity setSponsorapproved = new SetStateActivity();
            //由于工作流是默认命名，所以1和2都已经存在
            setSponsorapproved.Name = "setStateActivity3";
            setSponsorapproved.TargetStateName = "党委会审批";
            sponsoreven.Activities.Add(setSponsorapproved);

            //将状态活动添加进WorkflowChanges
            changes.TransientWorkflow.Activities.Add(sponsorsubmit);

            //将动态加载的活动更新至工作流
            workflowinstance.ApplyWorkflowChanges(changes);

            SetStateComboBox();

            this.button2.Enabled = false;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            StateMachineWorkflowInstance stateInstance = new StateMachineWorkflowInstance(workflowruntime, workflowinstance.InstanceId);
            stateInstance.SetState("介绍人提交意见");

            SponsorCommit(null, new ExternalDataEventArgs(workflowinstance.InstanceId));

            this.button3.Enabled = false;
            this.button2.Enabled = false;
        }

        private void button4_Click(object sender, EventArgs e)
        {
            PCApproved(null, new ExternalDataEventArgs(workflowinstance.InstanceId));
            this.button1.Enabled = false;
            this.button2.Enabled = false;
            this.button4.Enabled = false;
        }
    }
}

　　显示结果如下：

　　

　　当点击添加介绍人意见后，整个状态机工作流会在党委审批前，增加一个状态State，介绍人是否已提交意见。

1、取得工作流定义的对象，然后将它作为"WorkflowChanges"对象保存。
2、创建一个State对象，并设置其Name为"介绍人提交意见"。
3、往State内部添加一个EventDriven。
4、往EventDriven里面添加一个HandleExternalEvent子活动。并与接口中定义的事件进行绑定。
5、通过SetStateActivity活动的TargetStateName设置状态间的迁移关系，注意SetStateActivity活动也是EventDriven的子活动，也应该将它添加到EventDriven当中去。
6、将改动应用回工作流。