package com.jspservletcookbook;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.MalformedURLException;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.swing.text.html.HTMLEditorKit.ParserCallback;
import javax.swing.text.MutableAttributeSet;
import javax.swing.text.html.parser.ParserDelegator;
public class HtmlParseServlet extends HttpServlet {
private static final String BASE_URL = "http://finance.yahoo.com/q?d=t&s=";
private ParserDelegator htmlParser = null;
private MyParserCallback callback = null;
private String htmlText = "";
private boolean lastTradeFlag = false;
private boolean boldFlag = false;
private float stockVal = 0f;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
//set the MIME type of the response, "text/html"
response.setContentType("text/html");
//use a PrintWriter send text data to the client who has requested the servlet
java.io.PrintWriter out = response.getWriter();
//Begin assembling the HTML content
out.println("<html><head>");
out.println("<title>Stock Price Fetcher</title></head><body>");
out.println("<h2>Please submit a new valid stock symbol</h2>");
//make sure method="post" so that the servlet service method
//calls doPost in the response to this form submit
out.println(
"<form method=\"post\" action =\"" + request.getContextPath() +
"/stockservlet\" >");
out.println("<table border=\"0\"><tr><td valign=\"top\">");
out.println("Stock symbol: </td> <td valign=\"top\">");
out.println("<input type=\"text\" name=\"symbol\" size=\"10\">");
out.println("</td></tr><tr><td valign=\"top\">");
out.println("<input type=\"submit\" value=\"Submit Info\"></td></tr>");
out.println("</table></form>");
out.println("</body></html>");
} //end doGet
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws java.io.IOException{
String symbol;//this will hold the stock symbol
float price;
symbol = request.getParameter("symbol");
boolean isValid = (symbol == null || symbol.length() < 1) ? false : true;
//set the MIME type of the response, "text/html"
response.setContentType("text/html");
//use a PrintWriter send text data to the client who has requested the servlet
java.io.PrintWriter out = response.getWriter();
//Begin assembling the HTML content
out.println("<html><head>");
out.println("<title>Latest stock value</title></head><body>");
if (! isValid){
out.println("<h2>Sorry, the stock symbol parameter was either empty or null</h2>");
} else {
out.println("<h2>Here is the latest value of "+ symbol +"</h2>");
price = getLatestPrice(symbol);
//price < 1 ? "The symbol is probably invalid." :
out.println( (price == 0 ? "The symbol is probably invalid." : ""+price) );
}
out.println("</body></html>");
}// doPost
private float getLatestPrice(String symbol) throws IOException,MalformedURLException {
BufferedReader webPageStream = null;
URL stockSite = new URL(BASE_URL + symbol);
System.out.println(BASE_URL + symbol);
webPageStream = new BufferedReader(new InputStreamReader(stockSite.
openStream()));
htmlParser = new ParserDelegator();
callback = new MyParserCallback();
synchronized(htmlParser){//the code is designed to make calling parse() thread-safe
htmlParser.parse(webPageStream,callback,true);
}
return stockVal;
}//getLatestPrice
class MyParserCallback extends ParserCallback {
public MyParserCallback(){
if (stockVal != 0)
stockVal = 0f;
}
public void handleStartTag(javax.swing.text.html.HTML.Tag t,MutableAttributeSet a,int pos) {
if (lastTradeFlag && (t == javax.swing.text.html.HTML.Tag.B )){
boldFlag = true;
}
}//handleStartTag
public void handleText(char[] data,int pos){
htmlText = new String(data);
if (htmlText.indexOf("No such ticker symbol.") != -1){
throw new IllegalStateException(
"Invalid ticker symbol in handleText() method.");
} else if (htmlText.equals("Last Trade:")){
lastTradeFlag = true;
} else if (boldFlag){
try{
stockVal = new Float(htmlText).floatValue();
} catch (NumberFormatException ne) {
try{
// tease out any commas in the number using NumberFormat
java.text.NumberFormat nf = java.text.NumberFormat.getInstance();
Double f = (Double) nf.parse(htmlText);
stockVal = (float) f.doubleValue();
} catch (java.text.ParseException pe){
throw new IllegalStateException(
"The extracted text " + htmlText + " cannot be parsed as a number!");
}
}
lastTradeFlag = false;
boldFlag = false;
}//if
} //handleText
}//MyParserCallback
}//HttpServlet
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