在运行时评估groovy字符串表达式 [英] evaluating a groovy string expression at runtime

问题描述

如果我有以下代码(无效):

If I have code such as (which doesn’t work):

def value = element.getAttribute("value")
Binding binding = new Binding();
binding.setVariable("valueExpression", value);
def interpolatedValue = new GroovyShell(binding).evaluate("return valueExpression")
println ("interpolated Value = $interpolatedValue")

，并且xml属性中的值为时间为$ {new Date()}"

and the value from the xml attribute is "The time is ${new Date()}"

如何让Groovy在运行时评估此表达式?

how do I get Groovy to evaluate this expression at runtime?

使用上面的代码，我得到的是时间是$ {(new Date()}")，而不是求值结果….

Using the above code I get "The time is ${(new Date()}" instead of an evaluation….

感谢您的任何想法…….

Thanks for any thoughts….

推荐答案

嗯.首先，我以Michael的身份尝试过使用内联xml.但是看来，时髦可以正确地将它们视为GString.

Hmm. Firstly I have tried, as Michael, using inline xml. But It's seems, that groovy can properly treat them as GString.

因此，我设法通过另一种方式使事情工作:模板

So, I have managed make things to work using another way: Templates

def xml = new XmlSlurper().parse("test.xml")
def engine = new groovy.text.SimpleTemplateEngine()
def value = xml.em."@value".each { // iterate over attributes
    println(engine.createTemplate(it.text()).make().toString())
}

test.xml

<root>
    <em value="5"></em>
    <em value='"5"'></em>
    <em value='${new Date()}'></em>
    <em value='${ 5 + 4 }'></em>
</root>

输出

5
"5"
Wed Feb 26 23:01:02 MSK 2014
9

对于纯Groovy shell解决方案，我认为我们可以将表达式包装在其他"中，但是我还没有任何解决方案.

For pure Groovy shell solution, I think we can wrap expression in additional ", but I haven't get any solution yet.

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