Question

我有使用jDOM解析的XML文档，然后尝试获取满足XPath表达式的所有节点，但XPath始终不返回任何元素。这是我的XML文件：

<?xml version="1.0" encoding="UTF-8"?>

<!-- Using aggregate instance. Should pass -->

<pnml xmlns="http://www.pnml.org/version-2009/grammar/pnml">
    <net id="rootAgregate" type="http://www.cs.stu.cn.ua/jess/enets">
        <page id="main">
            <transition id="agregate1">
                <name>
                    <text>agregate1</text>
                    <graphics>
                        <offset x="22" y="-14"/>
                    </graphics>
                </name>
                <definition type="aggregate" subType="myAggregate"/>
                <graphics>
                    <position x="950" y="484"/>
                </graphics>
            </transition>
            <transition id="Input1">
                <name>
                    <text>agregate1</text>
                    <graphics>
                        <offset x="22" y="-14"/>
                    </graphics>
                </name>
                <definition type="input"/>
                <graphics>
                    <position x="950" y="484"/>
                </graphics>
            </transition>
            <transition id="Output1">
                <name>
                    <text>agregate1</text>
                    <graphics>
                        <offset x="22" y="-14"/>
                    </graphics>
                </name>
                <definition type="output"/>
                <graphics>
                    <position x="950" y="484"/>
                </graphics>
            </transition>
        </page>
    </net>
</pnml>

这是我的XPath代码：

private List<String> getChildNames(Document parsedDom) throws JDOMException {
        ArrayList<String> childNames = new ArrayList<String>();
        XPath childCounter = XPath.newInstance("//definition[@type=\"aggregate\"]");
        ListIterator<Element> listIterator = childCounter.selectNodes(parsedDom).listIterator();

        while (listIterator.hasNext()) {
            Element definitionElement = listIterator.next();
            childNames.add(definitionElement.getAttributeValue("subType"));
        }

        return childNames;
    }

我在这里检查了我的XPath表达式： http://www.whitebeam.org/library/guide/TechNotes/xpathtestbed.rhtm 它的工作原理。

为什么它在我的代码中不起作用？

提前谢谢你。

Answer 1

您需要xpath表达式中的命名空间。

How to use XPath on xml docs having default namespace

Parse XML with XPath & namespaces in Java

XPath不返回预期值

1 个答案: