activiti是支持juel表达式的，这个也很好用，但实际过程中需要支持类方法及变量。

原来项目中解析juel,这边有自定义一个方法的

代码如下：

public String getStringByELAndFormData(String el, Map formData) throws Exception {

ExpressionFactory factory = new ExpressionFactoryImpl();

SimpleContext context = new SimpleContext();

for (Object k : formData.keySet()) {

if (formData.get(k) != null) {

context.setVariable(k.toString(),

factory.createValueExpression(formData.get(k), formData.get(k).getClass()));

}

}

ValueExpression e = factory.createValueExpression(context, el, String.class);

return (String) e.getValue(context);

}

这种办法没有问题，但只局限于变量执行。但如果增加方法类调用就有问题！

如现在我有一个juely变量表达式，表达式为${fn_test.getJiebaoPost('','','')}。

该表达式需要调用以下类

public class FunctionOrgService {

public String getJiebaoPost(String id,String nodeFlag,String exParams){

return "82301111111";

}

}

原来解析的代码就有问题了，因为他没办法识别该函数.

解决办法如下

先在processEngine初始化时，增加函数的引入

Map map=new HashMap();

map.put("fn_test", new FunctionOrgService());

processEngineConfiguration.setBeans(map);

构造变量类VariableScope

特别说明一下，这个如果流程未结束，可以直接用流程实例对象ExecutionEntity代替，因为该类也继承了VariableScope。　　这边项目需要流程结束也要计算juel表达式，所以只能自己构造该对象

import java.util.Collection;

import java.util.HashMap;

import java.util.Map;

import java.util.Set;

import org.activiti.engine.delegate.VariableScope;

import org.activiti.engine.impl.persistence.entity.VariableInstance;

public class TestVariableScope implements VariableScope{

private Map variables=new HashMap();

public TestVariableScope(Map variables){

this.variables=variables;

}

@Override

public Map getVariables() {

// TODO Auto-generated method stub

return variables;

}

@Override

public Map getVariableInstances() {

/*// TODO Auto-generated method stub

Map variableInstanceMap=new HashMap();

System.out.println("通过Map.entrySet遍历key和value");

for (Map.Entry entry : variables.entrySet()) {

VariableInstanceEntity variableInstance=VariableInstanceEntity.create( entry.getKey(), type, entry.getValue())

}*/

return null;

}

@Override

public Map getVariables(Collection variableNames) {

// TODO Auto-generated method stub

return variables;

}

@Override

public Map getVariableInstances(Collection variableNames) {

// TODO Auto-generated method stub

return null;

}

@Override

public Map getVariables(Collection variableNames, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return variables;

}

@Override

public Map getVariableInstances(Collection variableNames,

boolean fetchAllVariables) {

// TODO Auto-generated method stub

return null;

}

@Override

public Map getVariablesLocal() {

// TODO Auto-generated method stub

return variables;

}

@Override

public Map getVariableInstancesLocal() {

// TODO Auto-generated method stub

return null;

}

@Override

public Map getVariablesLocal(Collection variableNames) {

// TODO Auto-generated method stub

return variables;

}

@Override

public Map getVariableInstancesLocal(Collection variableNames) {

// TODO Auto-generated method stub

return null;

}

@Override

public Map getVariablesLocal(Collection variableNames, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return variables;

}

@Override

public Map getVariableInstancesLocal(Collection variableNames,

boolean fetchAllVariables) {

// TODO Auto-generated method stub

return null;

}

@Override

public Object getVariable(String variableName) {

// TODO Auto-generated method stub

return variables.get(variableName);

}

@Override

public VariableInstance getVariableInstance(String variableName) {

// TODO Auto-generated method stub

return null;

}

@Override

public Object getVariable(String variableName, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return this.getVariable(variableName);

}

@Override

public VariableInstance getVariableInstance(String variableName, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return null;

}

@Override

public Object getVariableLocal(String variableName) {

// TODO Auto-generated method stub

return this.getVariable(variableName);

}

@Override

public VariableInstance getVariableInstanceLocal(String variableName) {

// TODO Auto-generated method stub

return null;

}

@Override

public Object getVariableLocal(String variableName, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return this.getVariable(variableName);

}

@Override

public VariableInstance getVariableInstanceLocal(String variableName, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return null;

}

@Override

public T getVariable(String variableName, Class variableClass) {

// TODO Auto-generated method stub

return null;

}

@Override

public T getVariableLocal(String variableName, Class variableClass) {

// TODO Auto-generated method stub

return null;

}

@Override

public Set getVariableNames() {

// TODO Auto-generated method stub

return null;

}

@Override

public Set getVariableNamesLocal() {

// TODO Auto-generated method stub

return null;

}

@Override

public void setVariable(String variableName, Object value) {

// TODO Auto-generated method stub

variables.put(variableName,value);

}

@Override

public void setVariable(String variableName, Object value, boolean fetchAllVariables) {

// TODO Auto-generated method stub

this.setVariable(variableName, value);

}

@Override

public Object setVariableLocal(String variableName, Object value) {

// TODO Auto-generated method stub

return null;

}

@Override

public Object setVariableLocal(String variableName, Object value, boolean fetchAllVariables) {

// TODO Auto-generated method stub

return null;

}

@Override

public void setVariables(Map variables) {

// TODO Auto-generated method stub

this.variables=(Map) variables;

}

@Override

public void setVariablesLocal(Map variables) {

// TODO Auto-generated method stub

this.variables=(Map) variables;

}

@Override

public boolean hasVariables() {

// TODO Auto-generated method stub

return variables.size()>0;

}

@Override

public boolean hasVariablesLocal() {

// TODO Auto-generated method stub

return variables.size()>0;

}

@Override

public boolean hasVariable(String variableName) {

// TODO Auto-generated method stub

return variables.containsKey(variableName);

}

@Override

public boolean hasVariableLocal(String variableName) {

// TODO Auto-generated method stub

return variables.containsKey(variableName);

}

@Override

public void createVariableLocal(String variableName, Object value) {

// TODO Auto-generated method stub

}

@Override

public void removeVariable(String variableName) {

// TODO Auto-generated method stub

}

@Override

public void removeVariableLocal(String variableName) {

// TODO Auto-generated method stub

}

@Override

public void removeVariables(Collection variableNames) {

// TODO Auto-generated method stub

}

@Override

public void removeVariablesLocal(Collection variableNames) {

// TODO Auto-generated method stub

}

@Override

public void removeVariables() {

// TODO Auto-generated method stub

}

@Override

public void removeVariablesLocal() {

// TODO Auto-generated method stub

}

}

以上代码只传入一个map即可,很多方法不需要实现.

3.执行juel的表达式

public class JuelExpressonCommand implements Command {

private static Logger logger = LoggerFactory.getLogger(JuelExpressonCommand.class);

/**

* 取消沟通

*/

private String el;

/**

* 流程变量

*/

private Map formData;

public JuelExpressonCommand(String el, Map formData) {

super();

this.el = el;

this.formData = formData;

}

@Override

public Object execute(CommandContext commandContext) {

ProcessEngineConfigurationImpl processEngineConfiguation=commandContext.getProcessEngineConfiguration();

ExpressionManager expressionManager=processEngineConfiguation.getExpressionManager();

Expression e = expressionManager.createExpression(el);

CdpVariableScope variableScope=new CdpVariableScope(formData);

return e.getValue(variableScope);

}

}

至此，该表达式解析OK!