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548

Appendix A

Servlet and JSP Quick Reference

Sending Data with GET and Processing the 

Results Directly (HTTP Tunneling)

1. Create a 

URL

 object referring to applet's home host. You usu 

ally build a URL based upon the hostname from which the applet 

was loaded. 

URL currentPage = getCodeBase();

String protocol = currentPage.getProtocol();

String host = currentPage.getHost();

int port = currentPage.getPort();

String urlSuffix = "/servlet/SomeServlet";

URL dataURL = new URL(protocol, host, port, urlSuffix);

2. Create a 

URLConnection

 object. The 

openConnection

method of 

URL

 returns a 

URLConnection

 object. This object 

will be used to obtain streams with which to communicate. 

URLConnection connection = dataURL.openConnection();

3. Instruct the browser not to cache the URL data. 

connection.setUseCaches(false); 

4. Set any desired HTTP headers. If you want to set HTTP 

request headers (see Chapter 4), you can use 

setRequest 

Property

 to do so. 

connection.setRequestProperty("header", "value");

5. Create an input stream. There are several appropriate 

streams, but a common one is 

BufferedReader

. It is at the 

point where you create the input stream that the connection to 

the Web server is actually established behind the scenes.

BufferedReader in =

new BufferedReader(new InputStreamReader(

connection.getInputStream()));

6. Read each line of the document. Simply read until you get 

null

.

String line;

while ((line = in.readLine()) != null) {

doSomethingWith(line);

}

7. Close the input stream. 

in.close();

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