XPath 处理器输出为字符串 [英] XPath processor output as string

问题描述

Java 中使用 javax.xml.xpath 进行标准 XPath 处理的工作方式如下:

Standard XPath processing in java with javax.xml.xpath works like this:

1. 我为要处理的xml提供名称
2. 我以字符串形式提供 xpath 表达式.
3. 我获得的答案存储为节点列表，或者最终存储为单个值，具体取决于我选择的输出类型.

我需要用 java 编写几个测试，它们基本上应该是这样的:我将 xpath 表达式作为字符串提供，并检查此表达式的 xpath 输出是否等于某个指定的输出(也作为字符串提供).所以我不需要遍历节点树和东西，我只需要获得 xpath 处理器输出作为字符串.有没有办法做到这一点?

I need to write a couple of tests in java which basically should work like this: I provide xpath expression as a string and it checks if xpath output of this expression equals to some specified output(also provided as string). So I dont need traversing through node tree and stuff, I just need to gain xpath processor output as a string. Is there any way to do this?

推荐答案

如果你使用

xPathExpression.evaluate(document);

其中 document 是您的 DOM 文档，然后它将返回它匹配的第一个节点的字符串表示.对于您认为 XPath 正在选择单个文本节点的用例，这可能很好.如果不是这种情况，您可以为从以下位置返回的 NodeList 编写一些 toString() 方法:

where document is your DOM document, then it will return a string representation of the first node it matches. That's probably fine for the use case where you believe that your XPath is selecting a single text node. If that's not the case, you could write some toString() method for NodeList that is returned from:

xPathExpression.evaluate(document, XPathConstants.NODESET);

编辑 1:这是一篇关于转换 NodeListSO 的文章/code> 到 XML 文档并打印它.

EDIT 1: Here's a SO article on converting a NodeList to an XML document and printing it.

编辑 2:如果您有使用 count 的 XPath 表达式或返回单个值的逻辑运算符，那么您可以捕获抛出的异常并采取适当的操作:

EDIT 2: If you have XPath expressions that use count or logical operators that return single values, then you could catch the exception thrown and take the appropriate action:

try {
    NodeList nodeList = (NodeList) xPathExpression.evaluate(document, XPathConstants.NODESET);
    for (int i = 0; i < nodeList.getLength(); i++) {
        Node node = nodeList.item(i);
        System.out.println(node.getNodeName());
    }
} catch (XPathExpressionException e) {
    String result = xPathExpression.evaluate(document);
    System.out.println(result);
}

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