[英]getChildNodes giving unexpected result
我的 XML 看起来像这样-
<collected_objects>
<object flag="complete" id="objId" version="1">
<variable_value variable_id="varId">ValueGoesHere</variable_value>
<reference item_ref="2"/>
</object>
<object comment="objComment" flag="complete" id="objId" version="1">
<reference item_ref="1"/>
</object>
</collected_objects>
我正在使用以下代码处理它-
Document dom = parser.getDocument();
NodeList collected_objects = dom.getElementsByTagName("object");
System.out.println("Number of collected objects are " + collected_objects.getLength());
for (int i = 0; i < collected_objects.getLength(); i++) {
Node aNode = collected_objects.item(i);
//get children of "objects"
NodeList refNodes = aNode.getChildNodes();
System.out.println("# of chidren are " + refNodes.getLength());
//print attributes of "objects"
NamedNodeMap attributes = aNode.getAttributes();
for (int a = 0; a < attributes.getLength(); a++) {
Node theAttribute = attributes.item(a);
System.out.println(theAttribute.getNodeName() + "=" + theAttribute.getNodeValue());
}
}
它输出为-
Number of collected objects are 2
# of chidren are 5
flag=complete
id=objId
version=1
# of chidren are 3
comment=objComment
flag=complete
id=objId
version=1
我的问题是为什么“孩子的数量”分别是 5 和 3? 我不应该分别期待 2 和 1 吗? 因为第一个对象有“ variable_value
”和“ reference
”,第二个对象只有“ reference
”
从本质上讲,我的目的是处理“对象”的孩子。
确保 <object> 节点子节点之间没有空格。 空格被视为子节点并按原样返回。
测试是否
childNode.getNodeType() == Node.ELEMENT_NODE
应该够了。
那是因为每个子节点之间有 2 个TEXT_NODE
( #text
)。
以下包括文本节点及其相应的值。
<object flag="complete" id="objId" version="1">
<TEXT_NODE />
<variable_value variable_id="varId">ValueGoesHere</variable_value>
<reference item_ref="2"/>
<TEXT_NODE />
</object>
这可以通过修改您的代码来验证:
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document dom = dBuilder.parse(new ByteArrayInputStream(S.getBytes()));
NodeList collected_objects = dom.getElementsByTagName("object");
System.out.println("Number of collected objects are "
+ collected_objects.getLength());
for (int i = 0; i < collected_objects.getLength(); i++) {
Node aNode = collected_objects.item(i);
// get children of "objects"
NodeList refNodes = aNode.getChildNodes();
System.out.println("# of chidren are " + refNodes.getLength());
//
for (int x = 0; x < refNodes.getLength(); x++) {
Node n = refNodes.item(x);
System.out.println(n.getNodeType() + " = " + n.getNodeName() + "/" + n.getNodeValue());
}
// print attributes of "objects"
NamedNodeMap attributes = aNode.getAttributes();
for (int a = 0; a < attributes.getLength(); a++) {
Node theAttribute = attributes.item(a);
System.out.println(theAttribute.getNodeName() + "="
+ theAttribute.getNodeValue());
}
}
输出:
Number of collected objects are 2
# of chidren are 5
3 = #text/
1 = variable_value/null
3 = #text/
1 = reference/null
3 = #text/
flag=complete
id=objId
version=1
# of chidren are 3
3 = #text/
1 = reference/null
3 = #text/
comment=objComment
flag=complete
id=objId
version=1
其中, 3 = TEXT_NODE
和 1 = ELEMENT_NODE
。
您只计算 ELEMENT 节点类型。 如果您只对子元素感兴趣,您可以更改代码以包含以下检查
if (aNode.getNodeType() == Node.ELEMENT_NODE)
{
...
}
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