TransformerFactory and Xalan Dependency Conflict

问题

I have the following code:

javax.xml.transform.TransformerFactory factory = TransformerFactory.newInstance();
factory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
javax.xml.transform.Transformer transformer = factory.newTransformer();

This works fine normally. However, I also need to add Xalan as a dependency in my pom.xml, and when I do, the above code now throws an error:

java.lang.IllegalArgumentException: Not supported: http://javax.xml.XMLConstants/property/accessExternalDTD

I think it has something to do with the fact that Xalan's jar has a different implementation of Transformer in it. How can I resolve this conflict without changing the above code and keeping Xalan as a dependency?

回答1:

Excluding Xerces from Xalan fixes this issue:

<dependency>
    <groupId>xalan</groupId>
    <artifactId>xalan</artifactId>
    <version>2.7.2</version>
    <exclusions>
        <exclusion>
            <groupId>xerces</groupId>
            <artifactId>xercesImpl</artifactId>
        </exclusion>
    </exclusions>
</dependency>

回答2:

If you are multiple XSL processors and or different versions, you have to handle the case that not every implementation will be able to handle every attribute. The only way to do so is to catch the IllegalArgumentException that is thrown if the attribute is not supported. Take a look at this modified example from the JAXP documentation:

javax.xml.transform.TransformerFactory factory = TransformerFactory.newInstance();

try {
    factory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
} catch (IllegalArgumentException e) {
    //jaxp 1.5 feature not supported
}

The documentation says:

When code change is possible, and for new development, it is recommended that the new properties be set as demonstrated above. By setting the properties this way, applications can be sure to maintain the desired behavior whether they are deployed to older or newer version of the JDK, or whether the properties are set through System Properties or jaxp.properties.

回答3:

The solution that worked for me was by doing this:

compile('org.opensaml:opensaml:2.6.1') {
    exclude group: 'xerces', module: 'xercesImpl'
    exclude module: 'xalan'
}

回答4:

It might be coming from other xalan version of your project.

Check Dependent Hierarchy in your POM for the xalan and exclude the xercesImpl in all the version of xalan.

来源：https://stackoverflow.com/questions/45152707/transformerfactory-and-xalan-dependency-conflict

标签

java

xml

maven

xalan