Using the Yahoo Search Marketing (formerly Overture) API with Java is unremarkably easy. The sample documentation provided by Yahoo! gives examples using Perl. Following these examples for making a request as a rough guide, there’re only a few simple changes to make with Java.

Posting a Request

To make the xml document, create a StringBuffer object, append the URL encoded strings using the URLencoder.encode method, be sure to manually encode spaces (the URLencoder.encode method escapes spaces as + signs, which you don’t want), and then convert the StringBuffer to a plain old String.
View a sample that requests a market state for “queryOut” returning a “numberListings” number of listings. “queryOut” is an encoded string. “numberListings” is an int. The first section of code takes a query and encodes it to produce “queryOut” so that it fits properly into the StringBuffer section.

Making the Post and Getting the Response

Posting the request requires you to open a new URL connection, post your output, read the response, and write it to an xml file:

URL url = new URL( postURL );
HttpURLConnection urlcon = (HttpURLConnection) url.openConnection();
urlcon.setRequestMethod(“POST”);
urlcon.setRequestProperty(“Content-type”, “application/x-www-form-urlencoded”);
urlcon.setDoOutput(true);
urlcon.setDoInput(true);
PrintWriter pout = new PrintWriter( new OutputStreamWriter(urlcon.getOutputStream(), “8859_1″), true);
pout.print( urlEncodedValue );
pout.flush();

InputStream in = urlcon.getInputStream();
BufferedReader bin = new BufferedReader( new InputStreamReader( in ) );

String response;
myfile = new File(filename);
FileWriter mywriter = new FileWriter(myfile);

while((response = bin.readLine()) != null) {
mywriter.write( response );
}

mywriter.close();

“filename” should be something.xml. Now you can parse the xml file, and use the response however you’d like.