X-Git-Url: http://wamblee.org/gitweb/?a=blobdiff_plain;f=crawler%2Fbasic%2Fsrc%2Forg%2Fwamblee%2Fcrawler%2FAbstractPageRequest.java;h=2e598005ff3a453150a50884cccfd649889ee3c6;hb=5685a836b9208ff8babfe5ac5b30c5f86d27cf96;hp=73132aa89736e8d06abd9a0e2cd1a310a4a96fa1;hpb=a5a9deb2dedb2efc96972acedaa44909a3b0fd79;p=utils diff --git a/crawler/basic/src/org/wamblee/crawler/AbstractPageRequest.java b/crawler/basic/src/org/wamblee/crawler/AbstractPageRequest.java index 73132aa8..2e598005 100644 --- a/crawler/basic/src/org/wamblee/crawler/AbstractPageRequest.java +++ b/crawler/basic/src/org/wamblee/crawler/AbstractPageRequest.java @@ -17,9 +17,10 @@ package org.wamblee.crawler; import java.io.ByteArrayOutputStream; -import java.io.File; import java.io.IOException; -import java.io.PrintStream; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; import javax.xml.transform.OutputKeys; import javax.xml.transform.Transformer; @@ -31,17 +32,18 @@ import javax.xml.transform.stream.StreamResult; import org.apache.commons.httpclient.Header; import org.apache.commons.httpclient.HttpClient; -import org.apache.commons.httpclient.HttpException; import org.apache.commons.httpclient.HttpMethod; import org.apache.commons.httpclient.HttpStatus; import org.apache.commons.httpclient.NameValuePair; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; +import org.apache.xml.serialize.OutputFormat; +import org.apache.xml.serialize.XMLSerializer; import org.w3c.dom.Document; import org.w3c.tidy.Tidy; -import org.wamblee.io.FileResource; -import org.wamblee.xml.XSLT; +import org.wamblee.xml.DomUtils; +import org.wamblee.xml.XslTransformer; /** * General support claas for all kinds of requests. @@ -49,127 +51,223 @@ import org.wamblee.xml.XSLT; public abstract class AbstractPageRequest implements PageRequest { private static final Log LOG = LogFactory.getLog(AbstractPageRequest.class); + private static final String REDIRECT_HEADER = "Location"; - - private int _maxTries; - private int _maxDelay; + + private int _maxTries; + + private int _maxDelay; private NameValuePair[] _params; + + private NameValuePair[] _headers; private String _xslt; - private PrintStream _os; + private XslTransformer _transformer; - protected AbstractPageRequest(int aMaxTries, int aMaxDelay, NameValuePair[] aParams, String aXslt, PrintStream aOs) { - if ( aParams == null ) { + /** + * Constructs the request. + * + * @param aMaxTries + * Maximum retries to perform. + * @param aMaxDelay + * Maximum delay before executing a request. + * @param aParams + * Request parameters to use. + * @param aHeaders + * Request headers to use. + * @param aXslt + * XSLT used to convert the response. + */ + protected AbstractPageRequest(int aMaxTries, int aMaxDelay, + NameValuePair[] aParams, NameValuePair[] aHeaders, String aXslt, XslTransformer aTransformer) { + if (aParams == null) { throw new IllegalArgumentException("aParams is null"); } - if ( aXslt == null ) { + if (aHeaders == null) { + throw new IllegalArgumentException("aHeaders is null"); + } + if (aXslt == null) { throw new IllegalArgumentException("aXslt is null"); } _maxTries = aMaxTries; _maxDelay = aMaxDelay; _params = aParams; + _headers = aHeaders; _xslt = aXslt; - _os = aOs; + _transformer = aTransformer; } - - /* (non-Javadoc) + + /* + * (non-Javadoc) + * * @see org.wamblee.crawler.PageRequest#overrideXslt(java.lang.String) */ public void overrideXslt(String aXslt) { - _xslt = aXslt; + _xslt = aXslt; } - - protected NameValuePair[] getParameters() { - return _params; + + /** + * Gets the parameters for the request. + * + * @param aParams Additional parameters to use, obtained from another page, most likely as + * hidden form fields. + * @return Request parameters. + */ + protected NameValuePair[] getParameters(NameValuePair[] aParams) { + List params = new ArrayList(); + params.addAll(Arrays.asList(_params)); + params.addAll(Arrays.asList(aParams)); + return params.toArray(new NameValuePair[0]); } - protected Document executeMethod(HttpClient client, HttpMethod method) throws TransformerException { - int triesLeft = _maxTries; - while ( triesLeft > 0 ) { + /** + * Gets the headers for the request. + * @return Request headers. + */ + protected NameValuePair[] getHeaders() { + return _headers; + } + + /** + * Executes the request with a random delay and with a maximum number of + * retries. + * + * @param aClient + * HTTP client to use. + * @param aMethod + * Method representing the request. + * @return XML document describing the response. + * @throws IOException + * In case of IO problems. + * @throws TransformerException + * In case transformation of the HTML to XML fails. + */ + protected Document executeMethod(HttpClient aClient, HttpMethod aMethod) + throws IOException, TransformerException { + + for (NameValuePair header: getHeaders()) { + aMethod.setRequestHeader(header.getName(), header.getValue()); + } + + int triesLeft = _maxTries; + while (triesLeft > 0) { triesLeft--; - try { - return executeMethodWithoutRetries(client, method); - } catch (TransformerException e) { - if ( triesLeft == 0 ) { + try { + return executeMethodWithoutRetries(aClient, aMethod); + } catch (TransformerException e) { + if (triesLeft == 0) { throw e; } } } throw new RuntimeException("Code should never reach this point"); } - - protected Document executeMethodWithoutRetries(HttpClient client, HttpMethod method) throws TransformerException { + /** + * Executes the request without doing any retries in case XSLT + * transformation fails. + * + * @param aClient + * HTTP client to use. + * @param aMethod + * Method to execute. + * @return XML document containing the result. + * @throws IOException + * In case of IO problems. + * @throws TransformerException + * In case transformation of the result to XML fails. + */ + protected Document executeMethodWithoutRetries(HttpClient aClient, + HttpMethod aMethod) throws IOException, TransformerException { try { - // Execute the method. - method = executeWithRedirects(client, method); - - // Transform the HTML into wellformed XML. - Tidy tidy = new Tidy(); - tidy.setXHTML(true); - tidy.setQuiet(true); - tidy.setShowWarnings(false); - if ( _os != null ) { - _os.println("Content of '" + method.getURI() + "'"); - _os.println(); - } - // We let jtidy produce raw output because the DOM it produces is - // is not namespace aware. We let the XSLT processor parse the XML again - // to ensure that the XSLT uses a namespace aware DOM tree. An alternative - // is to configure namespace awareness of the XML parser in a system wide way. - ByteArrayOutputStream xhtml = new ByteArrayOutputStream(); - tidy.parse(method.getResponseBodyAsStream(), xhtml); - _os.print(new String(xhtml.toByteArray())); - // Obtaining the XML as dom is not used. - //Document w3cDoc = tidy.parseDOM(method.getResponseBodyAsStream(), - // _os); - if ( _os != null ) { - _os.println(); - } - xhtml.flush(); - byte[] xhtmlData = xhtml.toByteArray(); - Document transformed = new XSLT().transform(xhtmlData, new FileResource(new File(_xslt))); - _os.println("Transformed result is: "); - Transformer transformer = TransformerFactory.newInstance().newTransformer(); + aMethod = executeWithRedirects(aClient, aMethod); + byte[] xhtmlData = getXhtml(aMethod); + + + Document transformed = _transformer.transform(xhtmlData, + _transformer.resolve(_xslt)); + ByteArrayOutputStream os = new ByteArrayOutputStream(); + Transformer transformer = TransformerFactory.newInstance() + .newTransformer(); transformer.setParameter(OutputKeys.INDENT, "yes"); transformer.setParameter(OutputKeys.METHOD, "xml"); - transformer.transform(new DOMSource(transformed), new StreamResult(_os)); - + transformer.transform(new DOMSource(transformed), new StreamResult( + os)); + LOG.debug("Transformed result is \n" + os.toString()); return transformed; - } catch (HttpException e) { - throw new RuntimeException(e.getMessage(), e); - } catch (IOException e) { - throw new RuntimeException(e.getMessage(), e); - } catch (TransformerConfigurationException e) { - throw new RuntimeException(e.getMessage(), e); + } catch (TransformerConfigurationException e) { + throw new TransformerException("Transformer configuration problem", e); } finally { // Release the connection. - method.releaseConnection(); + aMethod.releaseConnection(); } } - - private void delay() { + + /** + * Gets the result of the HTTP method as an XHTML document. + * + * @param aMethod + * Method to invoke. + * @return XHTML as a byte array. + * @throws IOException + * In case of problems obtaining the XHTML. + */ + private byte[] getXhtml(HttpMethod aMethod) throws IOException { + // Transform the HTML into wellformed XML. + Tidy tidy = new Tidy(); + tidy.setXHTML(true); + tidy.setQuiet(true); + tidy.setShowWarnings(false); + + // We write the jtidy output to XML since the DOM tree it produces is + // not namespace aware and namespace awareness is required by XSLT. + // An alternative is to configure namespace awareness of the XML parser + // in a system wide way. + ByteArrayOutputStream os = new ByteArrayOutputStream(); + Document w3cDoc = tidy.parseDOM(aMethod.getResponseBodyAsStream(), os); + DomUtils.removeDuplicateAttributes(w3cDoc); + LOG.debug("Content of response is \n" + os.toString()); + + ByteArrayOutputStream xhtml = new ByteArrayOutputStream(); + XMLSerializer serializer = new XMLSerializer(xhtml, new OutputFormat()); + serializer.serialize(w3cDoc); + xhtml.flush(); + + return xhtml.toByteArray(); + } + + /** + * Sleeps for a random time but no more than the maximum delay. + * + */ + private void delay() { try { - Thread.sleep((long)((float)_maxDelay* Math.random())); - } catch (InterruptedException e) { - // + Thread.sleep((long) ((float) _maxDelay * Math.random())); + } catch (InterruptedException e) { + return; // to satisfy checkstyle } } - /** + * Executes the request and follows redirects if needed. + * * @param aClient + * HTTP client to use. * @param aMethod + * Method to use. + * @return Final HTTP method used (differs from the parameter passed in in + * case of redirection). * @throws IOException - * @throws HttpException + * In case of network problems. */ - private HttpMethod executeWithRedirects(HttpClient aClient, HttpMethod aMethod) throws IOException, HttpException { + private HttpMethod executeWithRedirects(HttpClient aClient, + HttpMethod aMethod) throws IOException { delay(); int statusCode = aClient.executeMethod(aMethod); - switch (statusCode) { + switch (statusCode) { case HttpStatus.SC_OK: { return aMethod; } @@ -179,10 +277,12 @@ public abstract class AbstractPageRequest implements PageRequest { aMethod.releaseConnection(); Header header = aMethod.getResponseHeader(REDIRECT_HEADER); aMethod = new GetMethod(header.getValue()); - return executeWithRedirects(aClient, aMethod); // TODO protect against infinite recursion. + return executeWithRedirects(aClient, aMethod); // TODO protect + // against infinite + // recursion. } default: { - throw new RuntimeException("Method failed: " + throw new IOException("Method failed: " + aMethod.getStatusLine()); } }