JSoup元素和JSoup节点之间的区别 [英] Difference between JSoup Element and JSoup Node
问题描述
任何人都可以解释JSoup中提供的Element对象和Node对象之间的区别吗?
Can anyone please explain the difference between the Element object and Node object provided in JSoup ?
在哪种情况/条件下最好使用哪种?
Which is the best thing to be used in which situation/condition.
推荐答案
节点是DOM层次结构中任何类型的对象的通用名称.
A node is the generic name for any type of object in the DOM hierarchy.
元素是节点的一种特定类型.
An element is one specific type of node.
JSoup类模型反映了这一点:
The JSoup class model reflects this:
- Node
- Element
由于Element extends Node可以在Node上执行的任何操作，所以您也可以在Element上执行.但是Element提供了其他行为，例如，它更易于使用. Element具有诸如id和class等的属性，这些属性使在HTML文档中更容易找到它们.
Since Element extends Node anything you can do on a Node, you can do on an Element too. But Element provides additional behaviour which makes it easier to use, for example; an Element has properties such as id and class etc which make it easier to find them in a HTML document.
在大多数情况下，使用Element(或Document的其他子类之一)将满足您的需求，并且更容易进行编码.我怀疑唯一可能需要退回到Node的情况是DOM中是否存在特定的节点类型，而JSoup并未为其提供Node的子类.
In most cases using Element (or one of the other subclasses of Document) will meet your needs and will be easier to code to. I suspect the only scenario in which you might need to fall back to Node is if there is a specific node type in the DOM for which JSoup does not provide a subclass of Node.
下面的示例显示了同时使用Node和Element进行的HTML文档检查:
Here's an example showing the same HTML document inspection using both Node and Element:
String html = "<html><head><title>This is the head</title></head><body><p>This is the body</p></body></html>";
Document doc = Jsoup.parse(html);
Node root = doc.root();
// some content assertions, using Node
assertThat(root.childNodes().size(), is(1));
assertThat(root.childNode(0).childNodes().size(), is(2));
assertThat(root.childNode(0).childNode(0), instanceOf(Element.class));
assertThat(((Element) root.childNode(0).childNode(0)).text(), is("This is the head"));
assertThat(root.childNode(0).childNode(1), instanceOf(Element.class));
assertThat(((Element) root.childNode(0).childNode(1)).text(), is("This is the body"));
// the same content assertions, using Element
Elements head = doc.getElementsByTag("head");
assertThat(head.size(), is(1));
assertThat(head.first().text(), is("This is the head"));
Elements body = doc.getElementsByTag("body");
assertThat(body.size(), is(1));
assertThat(body.first().text(), is("This is the body"));
YMMV，但我认为Element表单更易于使用，更不容易出错.
YMMV but I think the Element form is easier to use and much less error prone.
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