Java:如何防止 EntityResolver#resolveEntity(String publicId, String systemId) 中的“systemId"被绝对化为当前工作目录

问题描述

我想解析以下 XML 文档以解析其中的所有实体:

 <doc>&title;</doc>

我的 EntityResolver 应该从数据库中获取具有给定系统 ID 的外部实体，然后进行解析，请参见下面的说明:

 私有静态类 MyEntityResolver{public InputSource resolveEntity(String publicId, String systemId)抛出 SAXException、IOException{//此时systemId总是绝对化为当前工作目录，//即使 XML 文档将其指定为相对的.//例如file:///H:/mydoc.dtd"而不是mydoc.dtd"//为什么???我怎样才能防止这种情况???SgmlEntity entity = findEntityFromDatabase(systemId);InputSource is = new InputSource(new ByteArrayInputStream(entity.getContents()));is.setPublicId(publicId);is.setSystemId(systemId);回报是；}}

我尝试使用 DOM (DocumentBuilder) 和 SAX (XMLReader)，将实体解析器设置为 MyEntityResolver(即 setEntityResolver(new MyEntityResolver()))，但是 systemId在 MyEntityResolver#resolveEntity(String publicId, String systemId) 中总是被绝对化到当前工作目录.

我也试过调用 setFeature("http://xml.org/sax/features/resolve-dtd-uris", false);，但这没有任何帮助.>

那么我怎样才能实现我想要的呢?

谢谢！

解决方案

显然还有一个接口叫做 EntityResolver2 这是旧 EntityResolver.(谈论混淆的名字！)

无论如何，我发现 EntityResolver2 实现了我想要的，也就是说，它不会对 systemId 做任何更改，因此它始终是指定的在 XML 文档中.

I want to parse the following XML document to resolve all entities in it:

 <!DOCTYPE doc SYSTEM 'mydoc.dtd'>
 <doc>&title;</doc>

My EntityResolver is supposed to fetch the external entity with the given system ID from the database and then do the resolution, see below for an illustration:

 private static class MyEntityResolver
 {
    public InputSource resolveEntity(String publicId, String systemId)
        throws SAXException, IOException
    {
        // At this point, systemId is always absolutized to the current working directory, 
        // even though the XML document specified it as relative.
        // E.g. "file:///H:/mydoc.dtd" instead of just "mydoc.dtd"
        // Why???  How can I prevent this???

        SgmlEntity entity = findEntityFromDatabase(systemId);
        InputSource is = new InputSource(new ByteArrayInputStream(entity.getContents()));
        is.setPublicId(publicId);
        is.setSystemId(systemId);
        return is;
    }
 }

I tried both using DOM (DocumentBuilder) and SAX (XMLReader), set the entity resolver to MyEntityResolver (i.e. setEntityResolver(new MyEntityResolver())), but systemId in MyEntityResolver#resolveEntity(String publicId, String systemId) is always being absolutized to the current working directory.

I also tried calling setFeature("http://xml.org/sax/features/resolve-dtd-uris", false);, but that didn't help anything.

So how can I achieve what I wanted?

Thanks!

解决方案

Apparently, there is another interface called EntityResolver2 which is the extension of the old EntityResolver. (Talk about confusing names!)

Anyway, I found that EntityResolver2 achieved what I wanted, that is, it does not make any changes to the systemId, so it will always exactly be what was specified in the XML document.

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