如何使用具有相同名称的标签遍历Java中的XML [英] How do I Iterate over an XML in Java, with tags, that have the same name
问题描述
我正在尝试使用DOM-Library(必须使用它)遍历Java中的这个xml文件,到目前为止,我已经能够通过直接以这种方式直接请求来获取某些元素:
I'm trying to iterate over this xml-file in Java using the DOM-Library(have to use it), and so far I've been able to get certain elements just by directly asking for it this way:
NodeList pList = document.getElementsByTagName("position");
Node pNode = pList.item(0);
Element pElement = (Element) pNode;
double xp = Double.parseDouble(pElement.getAttribute("x"));
double yp = Double.parseDouble(pElement.getAttribute("y"));
double zp = Double.parseDouble(pElement.getAttribute("z"));
,但是一旦我想要访问元素,它本身可能具有多个标签,这将不再起作用.例如,如果我要添加更多的Sphere,那么会有更多标记为Sphere的标签.
but this doesn't work anymore, once I want to access elements, that might have multiple tags in itself. for example, if I were to add more Spheres, there would be more tags labeled Sphere.
我尝试遍历Sphere/Lights标记,但是我似乎没有找到访问子标记的方法,这不依赖于我手动输入确切的行数.
I've tried to loop through the Sphere/Lights Tag, but I don't seem to find a way, to access the sub-tag, that doesn't rely on me manually typing in the exact number of rows.
我需要遍历所有表面/灯光标签,因为一旦获得所有信息,便会在收集数据的同时创建一个新的表面/灯光.
I need to iterate over all surface/light-tags, since once I have all the information I create a new surface/light in the instance of collecting the data for it.
<?xml version="1.0" standalone="no" ?>
<!DOCTYPE scene SYSTEM "scene.dtd">
<scene output_file="example1.png">
<background_color r="0.0" g="0.0" b="0.0"/>
<camera>
<position x="0.0" y="0.0" z="1.0"/>
<lookat x="0.0" y="0.0" z="-2.5"/>
<up x="0.0" y="1.0" z="0.0"/>
<horizontal_fov angle="45"/>
<resolution horizontal="512" vertical="512"/>
<max_bounces n="8"/>
</camera>
<lights>
<ambient_light>
<color r="1.0" g="1.0" b="1.0"/>
</ambient_light>
</lights>
<surfaces>
<sphere radius="1.0">
<position x="-2.1" y="0.0" z="-3.0"/>
<material_solid>
<color r="0.17" g="0.18" b="0.50"/>
<phong ka="0.3" kd="0.9" ks="1.0" exponent="200"/>
<reflectance r="0.0"/>
<transmittance t="0.0"/>
<refraction iof="2.3"/>
</material_solid>
</sphere>
<sphere radius="1.0">
<position x="0.0" y="0.0" z="-3.0"/>
<material_solid>
<color r="0.5" g="0.17" b="0.18"/>
<phong ka="0.3" kd="0.9" ks="1.0" exponent="200"/>
<reflectance r="0.0"/>
<transmittance t="0.0"/>
<refraction iof="2.3"/>
</material_solid>
</sphere>
<sphere radius="1.0">
<position x="2.1" y="0.0" z="-3.0"/>
<material_solid>
<color r="0.18" g="0.50" b="0.17"/>
<phong ka="0.3" kd="0.9" ks="1.0" exponent="200"/>
<reflectance r="0.0"/>
<transmittance t="0.0"/>
<refraction iof="2.3"/>
</material_solid>
</sphere>
</surfaces>
</scene>
推荐答案
document.getElementsByTagName(tagname)
searches all the Elements contained in the document.
element.getElementsByTagName(name)
searches all descendant Elements, i.e. only the sub-tree of the given element.
因此您可以这样做:
NodeList sphereList = document.getElementsByTagName("sphere");
for (int i = 0; i < sphereList.getLength(); i++) {
Element sphereElem = (Element) sphereList.item(i);
Element positionElem = (Element) sphereElem.getElementsByTagName("position").item(0);
double radius = Double.parseDouble(sphereElem.getAttribute("radius"));
double x = Double.parseDouble(positionElem.getAttribute("x"));
double y = Double.parseDouble(positionElem.getAttribute("y"));
double z = Double.parseDouble(positionElem.getAttribute("z"));
// use values here
}
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