[游戏开发]Flowable 一些异常报错、注意事项(4)

一、流程设计模型验证

如果自己手写对流程模型bpmn xml验证的话，需要验证的逻辑有点多，可以将flowable源码中对流程的验证移植过来。

例如：

import lombok.extern.slf4j.Slf4j;
import org.flowable.bpmn.converter.BpmnXMLConverter;
import org.flowable.bpmn.model.BpmnModel;
import org.flowable.common.engine.api.FlowableException;
import org.flowable.validation.ProcessValidator;
import org.flowable.validation.ProcessValidatorFactory;
import org.flowable.validation.ValidationError;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;


@Slf4j
public class ValidTest {
    public static void main(String[] args) {
        String flowDefXmlStr="<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?><definitions xmlns=\"http://www.omg.org/spec/BPMN/20100524/MODEL\" xmlns:bpmndi=\"http://www.omg.org/spec/BPMN/20100524/DI\" xmlns:custom=\"http://xx.com.cn\" xmlns:flowable=\"http://flowable.org/bpmn\" xmlns:omgdc=\"http://www.omg.org/spec/DD/20100524/DC\" xmlns:omgdi=\"http://www.omg.org/spec/DD/20100524/DI\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" expressionLanguage=\"http://www.w3.org/1999/XPath\" targetNamespace=\"http://xx.com.cn\" typeLanguage=\"http://www.w3.org/2001/XMLSchema\"><process id=\"F_ab6c15bec8cc48088c10ac1452ab0ad3\" isExecutable=\"true\" name=\"var2\"><sequenceFlow id=\"flow-f79c47d0-02f0-45d6-81c2-3786a6332602\" name=\"\" sourceRef=\"flow-9ba9ea5a-fb8c-48d7-adf0-ea9910895864\" targetRef=\"flow-c494fc41-cbac-4248-b936-df3254b92b88\"/><startEvent flowable:formKey=\"\" id=\"flow-9ba9ea5a-fb8c-48d7-adf0-ea9910895864\" name=\"开始\"><documentation/></startEvent><userTask flowable:candidateUsers=\"admin\" flowable:formKey=\"testform\" id=\"flow-c494fc41-cbac-4248-b936-df3254b92b88\" name=\"用户任务\"><documentation/></userTask><endEvent id=\"flow-6bfea0fc-0fad-47e4-aeef-b35fcad239ba\" name=\"结束\"><documentation/></endEvent></process></definitions>";
        try {
            validateProcess(flowDefXmlStr);
        }catch (Exception e){
            log.error("error info is :{}",  e.getMessage());
        }
    }


    private static void validateProcess(String flowDefXmlStr) throws UnsupportedEncodingException, XMLStreamException {
        // xml转bpmnModel,取bpmn2.0规范的xml
        InputStream bpmnStream = new ByteArrayInputStream(flowDefXmlStr.getBytes());
        XMLInputFactory xif = XMLInputFactory.newInstance();
        InputStreamReader in = new InputStreamReader(bpmnStream, "UTF-8");
        XMLStreamReader xtr = xif.createXMLStreamReader(in);
        // 然后转为bpmnModel
        BpmnModel bpmnModel = new BpmnXMLConverter().convertToBpmnModel(xtr);
        ProcessValidator validator = new ProcessValidatorFactory().createDefaultProcessValidator();
        List<ValidationError> errors = validator.validate(bpmnModel);
        System.out.println(errors);
    }

}

flowable 自身对模型的验证也是有局限的，更多的是对排他网关的流设计条件后是否有多条输出流，这样的错误能验证出来，其他的一些类型错误不识别，所以不是万能的。

二、对?UEL 表达式、表达式函数进行分解

Flowable 使用 UEL 进行表达式解析。UEL 代表统一表达式语言，是 EE6 规范的一部分。6.4.0版本增加了表达式函数。更多使用说明参考官方文档：https://www.flowable.com/open-source/docs/bpmn/ch04-API/#expression-functions

import org.apache.commons.lang3.StringUtils;

import java.text.StringCharacterIterator;
import java.util.ArrayList;
import java.util.List;


public class TestParseExpression {
    public static void main(String[] args) {
        String expression ="${vars:getOrDefault(user1, '1')},${vars:getOrDefault(user2, '19')},${vars:getOrDefault(user3, '22')}";
        List<String> result=TestParseExpression.parseDelimitedList(expression);
        System.out.println(result);
    }


    public static List<String> parseDelimitedList(String s) {
        List<String> result = new ArrayList<>();
        if (StringUtils.isNotEmpty(s)) {

            StringCharacterIterator iterator = new StringCharacterIterator(s);
            char c = iterator.first();

            StringBuilder strb = new StringBuilder();
            boolean insideExpression = false;

            while (c != StringCharacterIterator.DONE) {
                if (c == '{' || c == '$') {
                    insideExpression = true;
                } else if (c == '}') {
                    insideExpression = false;
                } else if (c == ',' && !insideExpression) {
                    result.add(strb.toString().trim());
                    strb.delete(0, strb.length());
                }

                if (c != ',' || insideExpression) {
                    strb.append(c);
                }

                c = iterator.next();
            }

            if (strb.length() > 0) {
                result.add(strb.toString().trim());
            }

        }
        return result;
    }
}

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