JAXP saxon-he：解析错误后 XMLfile StreamSource 不释放文件访问权限
JAXP saxon-he : XMLfile StreamSource doesn't release file access after parsing error
我正在使用 JAXP 规范 API 结合 Saxon-HE API，主要目的是开发一个应用程序，它使用可配置的 XSLT 样式表转换 XML 文件，能够覆盖生成的输出文档。我跳过了细节，因为我创建了一个示例项目来说明遇到的问题：
用例： 在转换错误的情况下，将 xml 文件移动到另一个目录（可能是错误目录）会引发访问异常。
当我基于 File 实例（指向 XML 文件）实例化 StreamSource 时，如果发生某些解析错误，移动文件会引发 "The process cannot access the file because it is being used by another process." 异常。
这是我写的一个 main-single-class 应用来说明这个问题：
package com.sample.xslt.application;
import net.sf.saxon.Configuration;
import net.sf.saxon.lib.FeatureKeys;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.stream.StreamSource;
public class XsltApplicationSample {
public static void main(String[] args) throws Exception {
if (args.length != 2) {
throw new RuntimeException("Two arguments are expected : <xslFilePath> <inputFilePath>");
}
String xslFilePath = args[0];
String xmlFilePath = args[1];
TransformerFactory factory = TransformerFactory.newInstance();
factory.setAttribute(FeatureKeys.ALLOW_MULTITHREADING, Boolean.TRUE);
factory.setAttribute(FeatureKeys.RECOVERY_POLICY,
new Integer(Configuration.RECOVER_WITH_WARNINGS));
Source xslSource = new StreamSource(new File(xslFilePath));
Source xmlSource = new StreamSource(new File(xmlFilePath));
Transformer transformer = factory.newTransformer(xslSource);
try {
transformer.transform(xmlSource, new DOMResult());
} catch (TransformerException e) {
System.out.println(e.getMessage());
}
// move input file to tmp directory (for example, could be configured error dir)
File srcFile = Paths.get(xmlFilePath).toFile();
File tempDir = new File(System.getProperty("java.io.tmpdir"));
Path destFilePath = new File(tempDir, srcFile.getName()).toPath();
try {
Files.move(srcFile.toPath(), destFilePath, StandardCopyOption.REPLACE_EXISTING);
} catch (SecurityException | IOException e) {
System.out.println(e.getMessage());
}
}
}
配置的 xslt 转换文件内容必须有效才能重现。
如果输入 xml 文件为空，则会产生 transformation/parsing 错误，但不会发生访问文件错误。
要重现的输入文件示例：
<root>
<elem>
</root>
标准输出示例：
JAXP: find factoryId =javax.xml.transform.TransformerFactory
JAXP: find factoryId =javax.xml.parsers.SAXParserFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl using ClassLoader: null
JAXP: find factoryId =javax.xml.parsers.SAXParserFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl using ClassLoader: null
JAXP: find factoryId =javax.xml.parsers.DocumentBuilderFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl using ClassLoader: null
JAXP: find factoryId =javax.xml.parsers.SAXParserFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl using ClassLoader: null
Error on line 3 column 3 of input_err.xml:
SXXP0003: Error reported by XML parser: The element type "elem" must be terminated by the
matching end-tag "</elem>".
org.xml.sax.SAXParseException; systemId: file:/C:/<path>/input_err.xml; lineNumber: 3; columnNumber: 3; The element type "elem" must be terminated by the matching end-tag "</elem>".
C:\<path>\input_err.xml -> C:\<path>\AppData\Local\Temp\input_err.xml: The process cannot access the file because it is being used by another process.
使用命令行（我使用 Eclipse）：
java ... -Djaxp.debug=1 -Dfile.encoding=UTF-8 -classpath <...> com.sample.xslt.application.XsltApplicationSample C:\<path>\transform.xsl C:\<path>\input_err.xml
用过 pom.xml:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.sample</groupId>
<artifactId>XsltExampleProject</artifactId>
<version>1.0.0-SNAPSHOT</version>
<name>XsltExampleProject</name>
<description>XSLT example project</description>
<dependencies>
<dependency>
<groupId>net.sf.saxon</groupId>
<artifactId>Saxon-HE</artifactId>
<version>9.7.0-7</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.2.1</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>
我使用的解决方法是将 xml 输入文件的内容作为字符串加载到内存中，请参见以下内容：
String xmlContent = FileUtils.readFileToString(new File(xmlFilePath), StandardCharsets.UTF_8);
Source xslSource = new StreamSource(new File(xslFilePath));
Source xmlSource = new StreamSource(new StringReader(xmlContent));
我在初始化 Transformer 时是否遗漏了什么？
默认解析的 SAX 解析器应该被 Saxon 推荐的另一个 API 覆盖？我认为 Xerces 解析器是根据调试日志记录使用的，但是它是否与 Saxon 提供的转换器实现完全兼容？
我对这个有点困惑..
感谢您的帮助！
从问题后面的评论线程来看，它似乎是 JDK 随附的 XML 解析器中的 bug/defect。您的选择是：
(a) 报告错误并耐心等待修复
(b) 改用 Apache Xerces 解析器
(c) 不提供文件，而是提供文件输入流，然后自行关闭。
我的建议是 (b)，因为 Apache Xerces 解析器比 JDK 中的版本可靠得多。
我正在使用 JAXP 规范 API 结合 Saxon-HE API，主要目的是开发一个应用程序，它使用可配置的 XSLT 样式表转换 XML 文件，能够覆盖生成的输出文档。我跳过了细节，因为我创建了一个示例项目来说明遇到的问题：
用例： 在转换错误的情况下，将 xml 文件移动到另一个目录（可能是错误目录）会引发访问异常。
当我基于 File 实例（指向 XML 文件）实例化 StreamSource 时，如果发生某些解析错误，移动文件会引发 "The process cannot access the file because it is being used by another process." 异常。
这是我写的一个 main-single-class 应用来说明这个问题：
package com.sample.xslt.application;
import net.sf.saxon.Configuration;
import net.sf.saxon.lib.FeatureKeys;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.stream.StreamSource;
public class XsltApplicationSample {
public static void main(String[] args) throws Exception {
if (args.length != 2) {
throw new RuntimeException("Two arguments are expected : <xslFilePath> <inputFilePath>");
}
String xslFilePath = args[0];
String xmlFilePath = args[1];
TransformerFactory factory = TransformerFactory.newInstance();
factory.setAttribute(FeatureKeys.ALLOW_MULTITHREADING, Boolean.TRUE);
factory.setAttribute(FeatureKeys.RECOVERY_POLICY,
new Integer(Configuration.RECOVER_WITH_WARNINGS));
Source xslSource = new StreamSource(new File(xslFilePath));
Source xmlSource = new StreamSource(new File(xmlFilePath));
Transformer transformer = factory.newTransformer(xslSource);
try {
transformer.transform(xmlSource, new DOMResult());
} catch (TransformerException e) {
System.out.println(e.getMessage());
}
// move input file to tmp directory (for example, could be configured error dir)
File srcFile = Paths.get(xmlFilePath).toFile();
File tempDir = new File(System.getProperty("java.io.tmpdir"));
Path destFilePath = new File(tempDir, srcFile.getName()).toPath();
try {
Files.move(srcFile.toPath(), destFilePath, StandardCopyOption.REPLACE_EXISTING);
} catch (SecurityException | IOException e) {
System.out.println(e.getMessage());
}
}
}
配置的 xslt 转换文件内容必须有效才能重现。 如果输入 xml 文件为空，则会产生 transformation/parsing 错误，但不会发生访问文件错误。
要重现的输入文件示例：
<root>
<elem>
</root>
标准输出示例：
JAXP: find factoryId =javax.xml.transform.TransformerFactory
JAXP: find factoryId =javax.xml.parsers.SAXParserFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl using ClassLoader: null
JAXP: find factoryId =javax.xml.parsers.SAXParserFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl using ClassLoader: null
JAXP: find factoryId =javax.xml.parsers.DocumentBuilderFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl using ClassLoader: null
JAXP: find factoryId =javax.xml.parsers.SAXParserFactory
JAXP: loaded from fallback value: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
JAXP: created new instance of class com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl using ClassLoader: null
Error on line 3 column 3 of input_err.xml:
SXXP0003: Error reported by XML parser: The element type "elem" must be terminated by the
matching end-tag "</elem>".
org.xml.sax.SAXParseException; systemId: file:/C:/<path>/input_err.xml; lineNumber: 3; columnNumber: 3; The element type "elem" must be terminated by the matching end-tag "</elem>".
C:\<path>\input_err.xml -> C:\<path>\AppData\Local\Temp\input_err.xml: The process cannot access the file because it is being used by another process.
使用命令行（我使用 Eclipse）：
java ... -Djaxp.debug=1 -Dfile.encoding=UTF-8 -classpath <...> com.sample.xslt.application.XsltApplicationSample C:\<path>\transform.xsl C:\<path>\input_err.xml
用过 pom.xml:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.sample</groupId>
<artifactId>XsltExampleProject</artifactId>
<version>1.0.0-SNAPSHOT</version>
<name>XsltExampleProject</name>
<description>XSLT example project</description>
<dependencies>
<dependency>
<groupId>net.sf.saxon</groupId>
<artifactId>Saxon-HE</artifactId>
<version>9.7.0-7</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.2.1</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>
我使用的解决方法是将 xml 输入文件的内容作为字符串加载到内存中，请参见以下内容：
String xmlContent = FileUtils.readFileToString(new File(xmlFilePath), StandardCharsets.UTF_8);
Source xslSource = new StreamSource(new File(xslFilePath));
Source xmlSource = new StreamSource(new StringReader(xmlContent));
我在初始化 Transformer 时是否遗漏了什么？ 默认解析的 SAX 解析器应该被 Saxon 推荐的另一个 API 覆盖？我认为 Xerces 解析器是根据调试日志记录使用的，但是它是否与 Saxon 提供的转换器实现完全兼容？ 我对这个有点困惑..
感谢您的帮助！
从问题后面的评论线程来看，它似乎是 JDK 随附的 XML 解析器中的 bug/defect。您的选择是：
(a) 报告错误并耐心等待修复
(b) 改用 Apache Xerces 解析器
(c) 不提供文件，而是提供文件输入流，然后自行关闭。
我的建议是 (b)，因为 Apache Xerces 解析器比 JDK 中的版本可靠得多。