| Listing 1 - Beginning of the doGet method. |
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import java.io.*;
import java.util.*;import javax.servlet.*;
import javax.servlet.http.*;public class Java4560a extends HttpServlet{
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException, IOException{ |
Get and save URL parameters named item
An HTTP URL can have multiple parameters with the same name. In this case, all of the parameters are named item . Listing 2 gets the values stored in all of the parameters named item and saves them in a String array named items .
(Each time the servlet is called, the size of the list of parameters increases by one.)
The fragment also instantiates and initializes a String object used later to construct a new parameter string for the URL.
| Listing 2 - Get and save URL parameters named item. |
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String parameters = "?";
String[]items = request.getParameterValues("item"); |
Construct the new parameter string
Listing 3 uses the parameter values from the old parameter string toconstruct a new parameter string. The new parameter string will later be concatenated to the URL for the servlet.
Listing 3 - Construct the new parameter string.
Concatenate current date and time to new parameter string
Listing 4 gets the current date and time in milliseconds and saves it in a long variable named theDate . Then it concatenates the current date and time in milliseconds onto the newparameter string that was constructed in Listing 3 .
| Listing 4 - Concatenate current date and time to new parameter string. |
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long theDate = new Date().getTime();
parameters = parameters + "item=" + theDate; |
Begin creation of the HTML page
Listing 5 begins the creation of the output HTML page. You have seen code like this before, so I won't discuss it further at this point.
| Listing 5 - Begin creation of the HTML page. |
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//Establish the type of output
response.setContentType("text/html");//Get an output streamPrintWriter out = response.getWriter();//Construct an HTML page and send it back to the client
out.println("<html>");
out.println("<head><title>Java4560a</title></head>");
out.println("<body>"); |
Construct the new hyperlink
Listing 6 constructs the hyperlink containing the URL for the servlet. Note that the hyperlink references a URL that includes the parameter stringconstructed above.
If you compile and run this servlet, you may need to substitute the name of your server in place of my server.
| Listing 6 - Construct the hyperlink. |
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out.println("<a href='http://localhost:8080/Java4560a"
+ parameters + "'>Click Here</a>") |
Introductory text
Listing 7 provides a line of introductory text for the list of dates and times to be displayed on the screen.
| Listing 7 - Introductory text. |
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out.println("<br/><br/>Your list of times is:<br/>"); |
Display date and time history
Listing 2 retrieved all of the data in the incoming URL parameters and saved that data in a String array named items .
If that array contains data, Listing 8 displays the date and time for each element in the array.