Question

我有这个XML文件，我想找到这些查询：

包含图片的所有图书
所有包含多张图片的图书
所有与“Larry Niven”一起写过书的作者

这是XML：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE inventory SYSTEM "books.dtd">
<inventory>
    <book num="b1">
        <title>Snow Crash</title>
        <author>Neal Stephenson</author>
        <publisher>Spectra</publisher>
        <price>14.95</price>
        <chapter>
            <title>Snow Crash - Chapter A</title>
            <paragraph>
                This is the <emph>first</emph> paragraph.
                <image file="firstParagraphImage.gif"/>
                afetr image...
            </paragraph>
            <paragraph>
                This is the <emph>second</emph> paragraph.
                <image file="secondParagraphImage.gif"/>
                afetr image...
            </paragraph>
        </chapter>
        <chapter>
            <title>Snow Crash - Chapter B</title>
            <section>
                <title>Chapter B - section 1</title>
                <paragraph>
                    This is the <emph>first</emph> paragraph of section 1 in chapter B.
                    <image file="Chapter_B_firstParagraphImage.gif"/>
                    afetr image...
                </paragraph>
                <paragraph>
                    This is the <emph>second</emph> paragraph of section 1 in chapter B.
                    <image file="Chapter_B_secondParagraphImage.gif"/>
                    afetr image...
                </paragraph>
            </section>
        </chapter>
        <chapter>
            <title>Chapter C</title>
            <paragraph>
                This chapter has no images and only one paragraph
            </paragraph>
        </chapter>
    </book>
    <book num="b2">
        <title>Burning Tower</title>
        <author>Larry Niven</author>
        <author>Jerry Pournelle</author>
        <publisher>Pocket</publisher>
        <price>5.99</price>
        <chapter>
            <title>Burning Tower - Chapter A</title>
        </chapter>
        <chapter>
            <title>Burning Tower - Chapter B</title>
            <paragraph>
                This is the <emph>second</emph> paragraph of chapter B in the 2nd book.
                <image file="Burning_Tower_Chapter_B_secondParagraphImage.gif"/>
                afetr image...
            </paragraph>
        </chapter>
    </book>
    <book num="b3">
        <title>Zodiac</title>
        <author>Neal Stephenson</author>
        <publisher>Spectra</publisher>
        <price>7.50</price>
        <chapter>
            <title>Zodiac - Chapter A</title>
        </chapter>
    </book>
    <!-- more books... -->
</inventory>

以下是我的答案：

1. /inventory/book[count(image)=1]/title
2. /inventory/book[count(image)>=1/title
3. /inventory/book[author=”Larry Niven”][count(author)>1]/author

但是当我使用Java XPath代码测试这些答案时，它不起作用。

错误在哪里？谢谢

Answer 1

您的前两个问题与文档中image的位置有关 - 需要从当前节点搜索并搜索所有子项（不仅仅是直接子项）：

/inventory/book[count(.//image) = 1]/title
/inventory/book[count(.//image) >= 1]/title

您的上一个引号有问题（需要使用单引号），还会重复Larry Niven。这是修复：

/inventory/book[author='Larry Niven'][count(author) > 1]/author[. != 'Larry Niven']

请注意，您可以改为使用and：

/inventory/book[author='Larry Niven' and count(author) > 1]/author[. != 'Larry Niven']

XPath查询 - 布尔条件

1 个答案: