关于java：Saxon-HE 9.3的javax.xml.xpath.XPathFactory提供程序-配置文件中的语法错误

Syntax error in javax.xml.xpath.XPathFactory provider-configuration file of Saxon-HE 9.3

我在Mac OS X和Saxon-HE 9.3.0.5上使用Java SE 6。 ServiceLoader无法找到javax.xml.xpath.XPathFactory的Saxon实现。

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mac:test2 ludo$ java -version
java version"1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03-383-11A511)
Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02-383, mixed mode)

javax.xml.xpath.XPathFactory的newInstance方法的javadoc在查找过程的第3点中声明以本地化实现：

The class loader is asked for service provider provider-configuration files matching javax.xml.xpath.XPathFactory in the resource directory META-INF/services. See the JAR File Specification for file format and parsing rules.

JAR文件规范的"服务提供者"部分指出：

The file should contain a newline-separated list of unique concrete provider-class names.

但是，如果我提取saxon9he.jar文件并查看META-INF目录，则会看到：

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mac:Java ludo$ mkdir test
mac:Java ludo$ cd test
mac:test ludo$ jar fx ../saxon9he.jar
mac:test ludo$ cat META-INF/services/javax.xml.xpath.XPathFactory
net.sf.saxon.xpath.XPathFactoryImpl
http\\://java.sun.com/jaxp/xpath/dom: net.sf.saxon.xpath.XPathFactoryImpl
http\\://saxon.sf.net/jaxp/xpath/om: net.sf.saxon.xpath.XPathFactoryImpl

第一行是正确的，但我看不到为什么有两行多余的行，并且看起来这些行给ServiceLoader造成了麻烦。我看到了一个测试示例的问题，该示例编写了理解用于查找提供程序的机制。我们可以看到saxon9he.jar在CLASSPATH中。

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mac:services ludo$ java ServicesTest
CLASSPATH = ..., /Users/ludo/Library/Java/saxon9he.jar, ...
Service XPathFactory: java.util.ServiceLoader[javax.xml.xpath.XPathFactory]
ServiceConfigurationError: javax.xml.xpath.XPathFactory: jar:file:/Users/ludo/Library/Java/saxon9he.jar!/META-INF/services/javax.xml.xpath.XPathFactory:2: Illegal configuration-file syntax

兴趣线是：

1	jar:file:/Users/ludo/Library/Java/saxon9he.jar!/META-INF/services/javax.xml.xpath.XPathFactory:2: Illegal configuration-file syntax

这是Saxon的错误还是系统不支持的扩展语法？我该怎么做才能解决这个问题？

请注意，如果我明确选择实现的类，则可以获得工厂。但是我想使用服务机制。以下代码有效：

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XPathFactory xpf = XPathFactory.newInstance(
XPathFactory.DEFAULT_OBJECT_MODEL_URI,
"net.sf.saxon.xpath.XPathFactoryImpl",
ClassLoader.getSystemClassLoader());

我在下面添加了整个Java测试程序。

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import java.net.URL;
import java.net.URLClassLoader;
import java.util.Iterator;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import javax.xml.xpath.XPathFactory;

public class ServicesTest {
public static String getClasspathString() {
StringBuilder classpath = new StringBuilder();
ClassLoader classLoader = ClassLoader.getSystemClassLoader();
URL[] urls = ((URLClassLoader) classLoader).getURLs();
for (int i = 0; i < urls.length - 1; i++) {
classpath.append(urls[i].getFile()).append(",");
}
if (urls.length > 0) {
classpath.append(urls[urls.length - 1].getFile());
}

return classpath.toString();
}

public static void availableProviders(ServiceLoader sl) {
Iterator it = sl.iterator();
int index = 0;
for (;;) {
try {
if (!it.hasNext()) {
break;
}
index++;
Object o = it.next();
System.out.printf("%03d Concrete class name: %s\
", index, o.getClass().getName());
} catch (ServiceConfigurationError e) {
System.err.printf("ServiceConfigurationError: %s\
", e.getMessage());
}
}
}

public static void main(String[] args) {
System.out.printf("CLASSPATH = %s\
", getClasspathString());
System.out.println();

ServiceLoader<XPathFactory> slXPathFactory = ServiceLoader.load(XPathFactory.class);
System.out.printf("Service XPathFactory: %s\
", slXPathFactory.toString());
availableProviders(slXPathFactory);
}
}