DocumentBuilderFactory 获得可用功能? [英] DocumentBuilderFactory get available features?

问题描述

我正在尝试在 DocumentBuilderFactory 上设置功能.但是，它只是抛出一个 javax.xml.parsers.ParserConfigurationException 并带有特性名称作为消息:

I am trying to set features on a DocumentBuilderFactory. However, it just throws a javax.xml.parsers.ParserConfigurationException with the features name as the message:

public void execute() throws Exception
{
    // Get the factory.
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

    // Xerces 1 - http://xerces.apache.org/xerces-j/features.html#external-general-entities
    // Xerces 2 - http://xerces.apache.org/xerces2-j/features.html#external-general-entities
    setFeature(dbf, "http://xml.org/sax/features/external-general-entities", false);

    // Xerces 2 only - http://xerces.apache.org/xerces-j/features.html#external-general-entities
    setFeature(dbf, "http://apache.org/xml/features/disallow-doctype-decl", true);

    ...
}

private void setFeature(DocumentBuilderFactory dbf, String name, boolean value)
{
    try {
        dbf.setFeature(name, value);
    } catch (ParserConfigurationException e) {
        e.printStackTrace(); // <- see below
    }
}

错误没有提供有用的信息:

The error gives no useful information:

javax.xml.parsers.ParserConfigurationException: http://xml.org/sax/features/external-general-entities
    at org.apache.harmony.xml.parsers.DocumentBuilderFactoryImpl.setFeature(DocumentBuilderFactoryImpl.java:101)
    at com.kounta.printing.epson.EpsonReceiptTranslator.setFeature(EpsonReceiptTranslator.java:76)
    at com.kounta.printing.epson.EpsonReceiptTranslator.execute(EpsonReceiptTranslator.java:49)
    at com.kounta.printing.epson.EpsonPrintJob$1.run(EpsonPrintJob.java:48)
    at com.kounta.util.TaskQueue.internalRun(TaskQueue.java:68)
    at com.kounta.util.TaskQueue.access$100(TaskQueue.java:11)
    at com.kounta.util.TaskQueue$InternalRunnable.run(TaskQueue.java:79)
    at java.lang.Thread.run(Thread.java:841)

有没有办法获得所有支持的功能?还是我做错了什么?这两个功能都会抛出异常.

Is there a way to get all the supported features? Or am I doing something wrong? Both features throw an exception.

推荐答案

所以事实证明默认提供的 XML 解析器是垃圾和不完整的(这并不奇怪，因为这是 android)，我最终发现了这个问题:

So it turns out that the XML parser that is shipped by default is rubbish and incomplete (not surprising since this is android) and I found the issue eventually:

https://android.googlesource.com/platform/libcore/+/6bcf32ab404c39b85d25430f6df16503ef3526cf/xml/src/main/java/org/apache/harmony/xml/parsers/DocumentBuilderFactoryImpl.java#101

因此，尽管文档要求所有 XML 解析器都支持 FEATURE_SECURE_PROCESSING -http://developer.android.com/reference/javax/xml/parsers/SAXParserFactory.html#setFeature(java.lang.String,%20boolean) - 确实如此不是.

So despite the documentation requiring that all XML parsers support FEATURE_SECURE_PROCESSING -http://developer.android.com/reference/javax/xml/parsers/SAXParserFactory.html#setFeature(java.lang.String,%20boolean) - this does not.

解决方案是我将不得不使用不同的库来处理 XML 的解析.

The solution is I will have to use a different library to handle the parsing of the XML.

这篇关于DocumentBuilderFactory 获得可用功能?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！