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发信人: dong (春天来了...), 信区: Java
标  题: 访问计数器---使用JAVA Applet和CGI
发信站: BBS 水木清华站 (Fri Apr 11 13:58:40 1997)

这里有个JAVA和CGI程序结合的访问计数器的例子.
其实单纯做访问计数器，只有CGI就够了.
但希望统计用户访问该主页的时间时,只用CGI好象就不行了. (本例没有这个功能. :PPP)

count.pl
--------------------------------------------------------------
#!/usr/local/bin/perl
# Increments a visit count stored in the file named
# "counter" and send the count as a plain text document.

# Print a minimal MIME header
    print "Content-type: text/plain\n\n";

    $counterfile = "counter";

# Open the counter file and get current count
    open(COUNTER, "$counterfile");

# Lock the file to guard against another process updating the
# file as this script uses it
    $lock_exclusive = 2;
    $unlock = 8;
    flock(COUNTER, $lock_exclusive);

# Read and increment the count
    $line = <COUNTER>;
    close(COUNTER);

    chop($line);
    $count = $line;
    $count++;

# Save the new count in the file
    open(COUNTER, ">$counterfile");
    print COUNTER ("$count\n");
    close(COUNTER);

# Remember to unlock the file
    flock(COUNTER, $unlock);

# Send count to caller
    print "$count\n";
------------------------------------------------------------
VisitCount.java

----------------------------------------------------------
//---------------------------------------------------------------
// File: VisitCount.java
// Accesses a CGI program to update visit count and display
// the current count.
// Compile with: javac VisitCount.java
/*
* The VisitCount class is a Java applet that accesses a CGI
* program at the host URL and retrieves the visitor count (the
* CGI program also updates the count). Then it displays the
* current count. Use an <applet> tag to embed this applet
* at the location where you want to display the count.
*/
//---------------------------------------------------------------
import java.awt.*;
import java.applet.*;
import java.net.*;
import java.io.*;
public class VisitCount extends java.applet.Applet
{
    String visitCount;  // String to store visitor count
// Class initialization method
    public void init()
    {
        try
        {
// Open the URL that counts visitors to this site
// *** Edit URL before using at your site ***
            URL url = new URL(
              "http://www.lnbsoft.com/exec-bin/count.pl?update=1");

// Open a data stream and read a single line
            try
            {
                DataInputStream in = new
                    DataInputStream(url.openStream());
                visitCount = in.readLine();
            }
            catch(IOException e) {}
        }
        catch(MalformedURLException e) {}
    }
// Method that paints the output
    public void paint(java.awt.Graphics gc)
    {
// Display the visitor count that was read from the URL
// Use whatever font style and color you want
// I used Helvetica for a message and a Courier font
// for the visitor count

        Font helv = new Font("Helvetica", Font.BOLD, 16);
        Font courier = new Font("Courier", Font.BOLD, 24);

        gc.setFont(helv);
        FontMetrics fm = gc.getFontMetrics();
        String message = "Visitor number: ";
        int xstart = 0;
        int ystart = fm.getHeight();
        gc.drawString(message, xstart, ystart);

// Advance horizontally by amount needed to display message
        xstart += fm.stringWidth(message);

// Change font to Courier and display the count
        gc.setFont(courier);
        gc.setColor(Color.red);
        gc.drawString(visitCount, xstart, ystart);
    }
}
-----------------------------------------------------------------

HTML文件中调用方法.
<applet code=VisitCount width=200 height=26 align=middle></applet>

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