java - 使用相同的输入流验证并读取

Question

我有一个网络服务，它从 xml 文件获取输入流。现在，我想用相同的输入流验证并读取它。我使用标记并重置它。

在 Glassfish 和 Websphere 上它运行良好。但是当我使用 openEJB 运行集成测试时，流将在验证后关闭。我可以在一个简单的例子中重现它。

如何更好地实现它？ validator 实现始终相同。但每个环境都使用输入流的另一种实现。

public class XMLReader {
public static void main(String[] args) {
    try {
        XMLReader reader = new XMLReader();
        InputStream stream = new BufferedInputStream(new FileInputStream(
                new File("myXML.xml")));
        reader.read(stream);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public void read(InputStream xmlInputStream) throws SAXException,
        IOException {
    if (xmlInputStream.markSupported()) {
        xmlInputStream.mark(0);
        validateXML(xmlInputStream);
        xmlInputStream.reset();
        readXML(xmlInputStream);
    }
}

private void readXML(InputStream xmlInputStream) {
    // READ xmInputStream with STAX, JAXB, etc. whatever

}

private void validateXML(InputStream xmlInputStream) throws SAXException,
        IOException {
    Source schemaFile = new StreamSource(new File("myXSD.xsd"));
    Source xmlFile = new StreamSource(xmlInputStream);
    SchemaFactory schemaFactory = SchemaFactory
            .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
    Schema schema = schemaFactory.newSchema(schemaFile);
    Validator validator = schema.newValidator();
    try {
        validator.validate(xmlFile);
        System.out.println("is valid");
    } catch (SAXException e) {
        System.out.println("is NOT valid");
        System.out.println("Reason: " + e.getLocalizedMessage());
    }
}
}

异常(exception):

  java.io.IOException: Stream closed
at java.io.BufferedInputStream.getBufIfOpen(BufferedInputStream.java:145)
at java.io.BufferedInputStream.reset(BufferedInputStream.java:414)
at xmltest.XMLReader.read(XMLReader.java:36)
at xmltest.XMLReader.main(XMLReader.java:27)

Answer 1

不幸的是，XML 解析器在完成读取后关闭流。我不明白为什么它真的会这样做，我不会建议任何人关闭他们不拥有的流。可能有一个我无法这么快理解的原因。

无论如何，您可以做的是拥有一个 BufferedInputStream，它不会关闭包装的 InputSteam:

public static void main(String[] args) {
    try (FileInputStream in = new FileInputStream(new File("myXML.xml"))){
        XMLReader reader = new XMLReader();
        InputStream stream = new BufferedInputStream(in) {
            @Override
            public void close() throws IOException {
               // don't close
            }
        };
        reader.read(stream);
    } catch (Exception e) {
        e.printStackTrace();
    }
}