问题描述
我正在使用SAX来解析XML文件。假设我希望我的应用程序仅处理具有根元素 animalList 的XML文件 - 如果根节点是其他东西,则SAX解析器应该终止解析。
I am using SAX to parse XML files. Let's suppose that I want my application to only deal with XML files with root element "animalList" - if the root node is something else, the SAX parser should terminate parsing.
使用DOM,你可以这样做:
Using DOM, you would do it like this:
...
Element rootElement = xmldoc.getDocumentElement();
if ( ! rootElement.getNodeName().equalsIgnoreCase("animalList") )
throw new Exception("File is not an animalList file.");
...
但我无法确定如何使用SAX - 我无法弄清楚如何告诉SAX解析器确定根元素。但是,我知道如何在任何时候停止解析(在发布)。
but I can't ascertain how to do it using SAX - I can't figure out how to tell the SAX parser to determine the root element. However, I know how to stop parsing at any point (after seing Tom's solution).
示例XML文件:
<?xml version="1.0" encoding="UTF-8"?>
<animalList version="1.0">
<owner>Old Joe</owner>
<dogs>
<germanShephered>Spike</germanShephered>
<australianTerrier>Scooby</australianTerrier>
<beagle>Ginger</beagle>
</dogs>
<cats>
<devonRex>Tom</devonRex>
<maineCoon>Keta</maineCoon>
</cats>
</animalList>
谢谢。
推荐答案
虽然我上次多次使用SAX并且不记得API,但我认为处理程序接收的第一个标记是根元素。所以,你应该创建一个布尔类成员来指示你是否已经检查了第一个元素:
Although I used SAX last time many years ago and do not remember the API by heart but I think that the first tag that your handler receives is the root element. So, you should just create a boolean class member that indicates whether you have already checked the first element:
boolean rootIsChecked = false;
然后写入你的处理程序:
Then write in your handler:
if (!rootIsChecked) {
if (!"animalList".equals(elementName)) {
throw new IllegalArgumentException("Wrong root element");
}
rootIsChecked = true;
}
// continue parsing...
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