htmlParser usage tutorial

Recently, I have been studying Lucene's full-text search. In many places, I need to parse or analyze Html content or Html pages. Lucene's own demo program also provides an Html Parser,

but it is not a pure Java solution. So I searched everywhere, I found a "HTMLParser" on the Internet.

I will post the code for full-text retrieval in Lucene in a few days. (Retrieve articles on this site, etc.).

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;

import org.htmlparser.Node;
import org.htmlparser.NodeFilter;
import org.htmlparser.Parser;
import org.htmlparser.filters.NodeClassFilter;
import org.htmlparser.filters.OrFilter;
import org.htmlparser.nodes.TextNode;
import org.htmlparser.tags.LinkTag;
import org.htmlparser.util.NodeList;
import org.htmlparser.util.ParserException;
import org.htmlparser.visitors.HtmlPage;
import org.htmlparser.visitors.TextExtractingVisitor;

import com.jscud.util.LogMan; //A logging class

/**
* Demonstrates the application of Html Parse.
*
* @author scud http://www.jscud.com
*/

public class ParseHtmlTest
{

public static void main(String[] args) throws Exception
{
String aFile = "e:/jscud/temp/test.htm";

String content = readTextFile(aFile, "GBK") ;

test1(content);
System.out.println("================================== ====);

test2(content);
System.out.println("============================== ======");

test3(content);
System.out.println("========================== ==========");

test4(content);
System.out.println("====================== ==============");

test5(aFile);
System.out.println("================== ==================");

//Accessing external resources is relatively slow
test5("http://www.jscud.com");
System. out.println("====================================");

}

/ **
* Read the file to analyze the content.
* filePath can also be a Url.
*
* @param resource file/Url
*/
public static void test5(String resource) throws Exception
{
Parser myParser = new Parser(resource);

//Set encoding
myParser.setEncoding("GBK");

HtmlPage visitor = new HtmlPage(myParser);

myParser.visitAllNodesWith(visitor);

String textInPage = visitor.getTitle();

System.out.println(textInPage);
}

/**
* Processed by page. For a standard Html page, this method is recommended.
*/
public static void test4(String content) throws Exception
{
Parser myParser;
myParser = Parser.createParser(content, "GBK");

HtmlPage visitor = new HtmlPage(myParser);

myParser.visitAllNodesWith(visitor) ;

String textInPage = visitor.getTitle();

System.out.println(textInPage);
}

/**
* Use Visitor mode to parse html pages.
*
* Small advantages: Translated symbols such as <>
* Disadvantages: There are many spaces and the link cannot be extracted
*
*/
public static void test3(String content) throws Exception
{
Parser myParser;
myParser = Parser.createParser(content, "GBK");

TextExtractingVisitor visitor = new TextExtractingVisitor();

myParser.visitAllNodesWith(visitor);

String textInPage = visitor.getExtractedText();

System. out.println(textInPage);
}

/**
* Get the content of normal text and links.
*
* Use filters.
*/
public static void test2(String content) throws ParserException
{
Parser myParser;
NodeList nodeList = null;

myParser = Parser.createParser( content, "GBK");

NodeFilter textFilter = new NodeClassFilter(TextNode.class);
NodeFilter linkFilter = new NodeClassFilter(LinkTag.class);

//Do not process meta for now
//NodeFilter metaFilter = new NodeClassFilter(MetaTag .class);

OrFilter lastFilter = new OrFilter();
lastFilter.setPredicates(new NodeFilter[] { textFilter, linkFilter });

nodeList = myParser.parse(lastFilter);

Node[] nodes = nodeList. toNodeArray();

for (int i = 0; i < nodes.length; i++)
{
Node anode = (Node) nodes[i];

String line = "";
if (anode instanceof TextNode )
{
TextNode textnode = (TextNode) anode;
//line = textnode.toPlainTextString().trim();
line = textnode.getText();
}
else if (anode instanceof LinkTag)
{
LinkTag linknode = (LinkTag) anode;

line = linknode.getLink();
//@todo Filter jsp tags: You can implement this function yourself
//line = StringFunc.replace(line, "<%.*%> ;", "");
}

if (isTrimEmpty(line))
continue;

System.out.println(line);
}
}

/**
* Parse ordinary text nodes.
*
* @param content
* @throws ParserException
*/
public static void test1(String content) throws ParserException
{
Parser myParser;
Node[] nodes = null;

myParser = Parser.createParser(content, null);

nodes = myParser.extractAllNodesThatAre(TextNode.class); //exception could be thrown here

for (int i = 0; i < nodes.length; i++)
{
TextNode textnode = (TextNode) nodes[i];
String line = textnode.toPlainTextString().trim();
if (line.equals(""))
continue;
System.out.println(line);
}

}

/**
* Read a file into a string.
*
* @param sFileName file name
* @param sEncode String
* @return file content
*/
public static String readTextFile(String sFileName, String sEncode)
{
StringBuffer sbStr = new StringBuffer();

try
{
File ff = new File(sFileName);
InputStreamReader read = new InputStreamReader(new FileInputStream(ff),
sEncode);
BufferedReader ins = new BufferedReader(read);

String dataLine = "";
while (null != (dataLine = ins.readLine()))
{
sbStr.append(dataLine);
sbStr.append("rn");
}

ins.close();
}
catch (Exception e)
{
LogMan.error("read Text File Error", e);
}

return sbStr.toString();
}

/**
* Whether the string is empty after removing left and right spaces
* @param astr String
* @return boolean
*/
public static boolean isTrimEmpty(String astr)
{
if ((null == astr) || (astr.length() == 0))
{
return true;
}
if (isBlank(astr.trim()))
{
return true;
}
return false;
}

/**
* Whether the string is empty: null or the length is 0.
* @param astr source string.
* @return boolean
*/
public static boolean isBlank(String astr)
{
if ((null == astr) || (astr.length() == 0))
{
return true;
}
else
{
return false;
}
}

}

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