Question

我有以下xml

<map>
    <textures>
        <texture id="1" name="texturetest" />
        <texture id="2" name="ground1" />
    </textures>
    <tiles standardheight="60" standardwidth="60">
        <tile id="1" textureid="2">
            <attributes>
                <attribute name="slope" value="0" />
                <attribute name="slopedirection" value="left" />
                <attribute name="friction" value="3" />
                <attribute name="traversable" value="true"/>
            </attributes>
            <boundingbox type="box" width="60" height="60" />
        </tile>
    </tiles>
    <moveables>
        <object id="1" name="player1" textureid="1" width="60" height="60">
            <attributes>
                <attribute name="score" value="0" />
            </attributes>
            <boundingbox type="box" width="60" height="60" />
        </object>
    </moveables>
    <background>
        <layer name="bg1" zdistance="30" />
    </background>
    <tilemap>
        <tile tileid="1" x="0" y="200" />
        <tile tileid="1" x="60" y="200" />
    </tilemap>
    <objectmap>
        <object objectid="1" initial_x="0" initial_y="0" initial_speed="50" initial_direction="90" />
    </objectmap>
</map>

我使用以下xpath来获取moveables / object /

NodeList nodes = (NodeList) _path.evaluate("//map//moveables/object", nodesdoc, XPathConstants.NODESET);
            for (int i = 0; i < nodes.getLength(); i++) {
               NodeList attList = (NodeList) _path.evaluate("//attribute", nodes.item(i), XPathConstants.NODESET);
               for (int x = 0; x < attList.getLength(); x++) {
                    String name = attList.item(x).getAttributes().getNamedItem("name").getNodeValue();
                    String value = attList.item(x).getAttributes().getNamedItem("value").getNodeValue();
                    t.Attributes.put(name, value);

                }
            }

然而，这会循环遍历文档中的所有“属性”元素，而不仅仅是“对象”中的属性元素。

有人能说清楚为什么会这样吗？

此外，如果我调用nodes.item（i）.getChildNodes（）;我得到一个空引用异常.....

Answer 1

尝试在第二个XPath的开头添加一个点，表示Xpath意味着相对于当前nodes.item(i)：

NodeList attList = (NodeList)_path.evaluate(".//attribute", nodes.item(i), XPathConstants.NODESET);

Java Xpath如何读取子元素？

1 个答案: