Java Reference
In-Depth Information
112.
catch
(Exception ex)
113.
{
114.
System.out.println("Problem in GO!: URL not found.");
115.
}
116.
}//
ifelse
117.
}//
method
118.
}//
internal class
119.
}
■
22.4
Reading a web page
In the previous section we saw how HTML pages can displayed in a formatted way.
Now we show how the source code of a web page can be read. This is useful if the
application has to read and process information from the page. An example for
extracting information from the web is given in the next section.
Our non-graphical program
ReadURL
accesses a web page and writes its source
code to the console. We use one of the test pages for this topic, namely:
http://www.imm.dtu.dk/swingbook/HTMLTest/test1.html
In our application we create a
URL
-object with this address. Then an
InputStream
for reading from that URL is created. This is done by using method
openStream()
of class
URL
.Wethen use method
read()
of class
InputStream
to read the source
of the HTML page character by character. Each character is immediately written
to the console. The code of
ReadURL
and the resulting console output are listed
below.
File:
its/OnlineMonitor/ReadURL.java
1.
package
its.OnlineMonitor;
2.
3.
import
java.io.InputStream;
4.
import
java.net.URL;
5.
6.
public class
ReadURL {
7.
8.
private static
String immURL =
"http://www.imm.dtu.dk/swingbook/HTMLTest/test1.html";
9.
10.
public static void
main(String[] args) {
readAndPrintTheURL(immURL);
11.
}
12.
13.
14.
public static void
readAndPrintTheURL(String urlName){
// Create a URL
15.
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