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Camunda如何调用Java自定义类

Camunda

在Camunda中 ， 有四种方法来声明如何调用JAVA逻辑:
 

  1. 指定实现JavaDelegate或ActivityBehavior的类
  2. 计算解析为委托对象的表达式
  3. 调用方法表达式
  4. 求值表达式的值
 
本文重点描述基于JavaDelegate配置Camunda 的自动化服务节点 ， 在JavaDelegate实现类里完成逻辑计算 ， 并把计算结果返回给流程变量 。
 
一、设计流程图 
Camunda如何调用Java自定义类

文章插图
 
要指定在进程执行期间调用的类 ， camunda:class属性需要提供完全限定的类名 。要实现可以在流程执行期间调用的类 ， 这个类需要实现
org.camunda.bpm.engine.delegate.JavaDelegate接口 ， 并在execute方法中提供所需的逻辑 。当流程执行到达这个特定的步骤时 ， 它将执行该方法中定义的逻辑 ， 并以默认的BPMN 2.0方式保留活动 。
 
作为示例 ， 让我们创建一个Java类 ， 实现里模拟业务逻辑 。这个类需要实现
org.camunda.bpm.engine.delegate.JavaDelegate接口 ， 它需要我们实现execute(DelegateExecution)方法 。引擎将调用这个操作 ， 并且需要包含业务逻辑 。流程实例信息(如流程变量和其他信息)可以通过DelegateExecution接口访问和操作 。
 
JavaDelegate示例实现类：
 
package com.example.demo1;import org.camunda.bpm.engine.delegate.DelegateExecution;import org.camunda.bpm.engine.delegate.JavaDelegate;/** * 贷款计算类 */public class LoanDelegateimplements JavaDelegate {@Overridepublic void execute(DelegateExecution delegateExecution) throws Exception {Double yearWages = (Double) delegateExecution.getVariable("yearWages");Double houseAssets = (Double) delegateExecution.getVariable("houseAssets");double sum = yearWages + houseAssets;if(sum<=0){delegateExecution.setVariable("creditRating","C");delegateExecution.setVariable("loanLimit",0);}elseif(sum>0 && sum <=100){delegateExecution.setVariable("creditRating","B");delegateExecution.setVariable("loanLimit",sum*0.8);}elseif(sum>100){delegateExecution.setVariable("creditRating","A");delegateExecution.setVariable("loanLimit",sum*1.2);}}} 
以下是完整的BPMN模型文件：
 
<?xml version="1.0" encoding="UTF-8"?><bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:camunda="http://camunda.org/schema/1.0/bpmn" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_1wr7a1v" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="4.8.1" modeler:executionPlatform="Camunda Platform" modeler:executionPlatformVersion="7.15.0"><bpmn:process id="Process_0a6gw7u" name="贷款申请流程Java" isExecutable="true"><bpmn:startEvent id="StartEvent_1"><bpmn:outgoing>Flow_0kzdck2</bpmn:outgoing></bpmn:startEvent><bpmn:sequenceFlow id="Flow_0kzdck2" sourceRef="StartEvent_1" targetRef="Activity_1l6o8wm" /><bpmn:sequenceFlow id="Flow_0h8bikl" sourceRef="Activity_1l6o8wm" targetRef="Activity_1wjgiji" /><bpmn:userTask id="Activity_1wjgiji" name="确认贷款额度" camunda:assignee="demo"><bpmn:incoming>Flow_0h8bikl</bpmn:incoming><bpmn:outgoing>Flow_03h3srs</bpmn:outgoing></bpmn:userTask><bpmn:sequenceFlow id="Flow_03h3srs" sourceRef="Activity_1wjgiji" targetRef="Event_0myx83u" /><bpmn:endEvent id="Event_0myx83u"><bpmn:incoming>Flow_03h3srs</bpmn:incoming></bpmn:endEvent><bpmn:serviceTask id="Activity_1l6o8wm" name="计算贷款额度" camunda:class="com.example.demo1.LoanDelegate"><bpmn:incoming>Flow_0kzdck2</bpmn:incoming><bpmn:outgoing>Flow_0h8bikl</bpmn:outgoing></bpmn:serviceTask></bpmn:process><bpmndi:BPMNDiagram id="BPMNDiagram_1"><bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_0a6gw7u"><bpmndi:BPMNEdge id="Flow_03h3srs_di" bpmnElement="Flow_03h3srs"><di:waypoint x="600" y="117" /><di:waypoint x="692" y="117" /></bpmndi:BPMNEdge><bpmndi:BPMNEdge id="Flow_0h8bikl_di" bpmnElement="Flow_0h8bikl"><di:waypoint x="390" y="117" /><di:waypoint x="500" y="117" /></bpmndi:BPMNEdge><bpmndi:BPMNEdge id="Flow_0kzdck2_di" bpmnElement="Flow_0kzdck2"><di:waypoint x="215" y="117" /><di:waypoint x="290" y="117" /></bpmndi:BPMNEdge><bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1"><dc:Bounds x="179" y="99" width="36" height="36" /></bpmndi:BPMNShape><bpmndi:BPMNShape id="Activity_187in45_di" bpmnElement="Activity_1wjgiji"><dc:Bounds x="500" y="77" width="100" height="80" /></bpmndi:BPMNShape><bpmndi:BPMNShape id="Event_0myx83u_di" bpmnElement="Event_0myx83u"><dc:Bounds x="692" y="99" width="36" height="36" /></bpmndi:BPMNShape><bpmndi:BPMNShape id="Activity_05149db_di" bpmnElement="Activity_1l6o8wm"><dc:Bounds x="290" y="77" width="100" height="80" /></bpmndi:BPMNShape></bpmndi:BPMNPlane></bpmndi:BPMNDiagram></bpmn:definitions>


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