Question

如何在以下示例中使用Java Dom检查XML中是否存在特定的子代码：我正在查找所有userFiled次出现，而在第一部分中，没有。所以我想说如果没有标记userField做某事。

<element class="AufOrgKombination" hash="AOK_1416092142370_76">
    <field name="layer">4</field>
    <field name="name">Function organisation unit combination 1</field>
    <field name="description"/>
</element>
<element class="AufOrgKombination" hash="AOK_1417643334024_77">
    <field name="layer">4</field>
    <field name="name">Function organisation unit combination 1</field>
    <field name="description"/>
    <userField hash="USERFIELD_1415779871581_0">3.0</userField>
    <userField hash="USERFIELD_1415779871581_0">N.A.</userField>
</element>

类似的东西：

NodeList NodeuserField = element.getElementsByTagName("userField");
Element line;

for (int j = 0, l = NodeuserField.getLength(); j < l; j++) {
    line = (Element) NodeuserField.item(j);
    for (Entry<String, String> userFieldUserDef : map_userField.entrySet()) {
        if (element.getElementsByTagName("hash") == null) {
                                //Do Something
        }
    }
}

Answer 1

就像在this question中一样，我建议再次使用XPath。你可以通过Java XPath API（很糟糕）来做，或者再次使用data projection（是的，我是这个项目的附属机构）。如果存在元素，通过XPath确定有几种可能性。您可以尝试读取它并测试结果是否为null。这里作为替代方案：直接声明一个布尔投影方法：</ p>

public class ElementExists {

    public interface Projection {

        interface Element {
            @XBRead("./@hash")
            String getHash();

            @XBRead("count(./userField)>0")
            boolean hasUserField();
        }

        @XBRead("//element")
        List<Element> getElements();
    }

    public static void main(final String[] args) throws IOException {
        Projection projection = new XBProjector().io().url("resource://data.xml").read(Projection.class);
        for (Projection.Element e : projection.getElements()) {
            System.out.print("Element with hash '" + e.getHash() + "' has ");
            System.out.println((e.hasUserField() ? "" : "no ") + "user field");
        }
    }
}

此程序打印出来

Element with hash 'AOK_1416092142370_76' has no user field
Element with hash 'AOK_1417643334024_77' has user field

使用Java Dom查找XMl中是否存在标记名称

1 个答案: