Example usage for org.xml.sax.ext Locator2 getEncoding

Introduction

In this page you can find the example usage for org.xml.sax.ext Locator2 getEncoding.

Prototype

public String getEncoding();

Source Link

Document

Returns the name of the character encoding for the entity.

Usage

From source file:hudson.XmlFile.java

/**
 * Parses the beginning of the file and determines the encoding.
 *
 * @throws IOException/* w w w  .  ja  v  a 2  s .c o m*/
 *      if failed to detect encoding.
 * @return
 *      always non-null.
 */
public String sniffEncoding() throws IOException {
    class Eureka extends SAXException {
        final String encoding;

        public Eureka(String encoding) {
            this.encoding = encoding;
        }
    }

    try (InputStream in = Files.newInputStream(file.toPath())) {
        InputSource input = new InputSource(file.toURI().toASCIIString());
        input.setByteStream(in);
        JAXP.newSAXParser().parse(input, new DefaultHandler() {
            private Locator loc;

            @Override
            public void setDocumentLocator(Locator locator) {
                this.loc = locator;
            }

            @Override
            public void startDocument() throws SAXException {
                attempt();
            }

            @Override
            public void startElement(String uri, String localName, String qName, Attributes attributes)
                    throws SAXException {
                attempt();
                // if we still haven't found it at the first start element, then we are not going to find it.
                throw new Eureka(null);
            }

            private void attempt() throws Eureka {
                if (loc == null)
                    return;
                if (loc instanceof Locator2) {
                    Locator2 loc2 = (Locator2) loc;
                    String e = loc2.getEncoding();
                    if (e != null)
                        throw new Eureka(e);
                }
            }
        });
        // can't reach here
        throw new AssertionError();
    } catch (Eureka e) {
        if (e.encoding != null)
            return e.encoding;
        // the environment can contain old version of Xerces and others that do not support Locator2
        // in such a case, assume UTF-8 rather than fail, since Jenkins internally always write XML in UTF-8
        return "UTF-8";
    } catch (SAXException e) {
        throw new IOException("Failed to detect encoding of " + file, e);
    } catch (InvalidPathException e) {
        throw new IOException(e);
    } catch (ParserConfigurationException e) {
        throw new AssertionError(e); // impossible
    }
}

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