URLdemo, opens a connection
to a website specified by a URL (Uniform Resource Locator) to read
text from a file at that site.
URLdemo constructs an object of the Java® API
java.net.URL, which enables convenient handling
of URLs. Then, it calls a method on the URL object, to open a connection.
To read and display the lines of text at the site,
classes from the Java I/O package
It creates an
InputStreamReader object, and then
uses that object to construct a
Finally, it calls a method on the
to read the specified number of lines from the site.
The major tasks performed by
Construct a URL object.
The example first calls a constructor on
assigns the resulting object to variable
takes a single argument, the name of the URL to be accessed, as a
string. The constructor checks whether the input URL has a valid form.
url = java.net.URL('http://www.mathworks.com')
Open a connection to the URL.
The second statement of the example calls the method,
url, to establish
a connection with the website named by the object. The method returns
InputStream object to variable,
for reading bytes from the site.
is = openStream(url);
Set up a buffered stream reader.
The next two lines create a buffered stream reader for characters.
java.io.InputStreamReader constructor is called
with the input stream
is, to return to variable
object that can read characters. Then, the
is called with
isr, to return a
br. A buffered reader provides for
efficient reading of characters, arrays, and lines.
isr = java.io.InputStreamReader(is); br = java.io.BufferedReader(isr);
Read and display lines of text.
The following statements read the lines of HTML text from the
site, looking for text beginning with a paragraph tag,
Within the MATLAB®
while loop, the
each line of text (terminated by a
line feed character) from the site.
p1 = java.lang.String('<p>'); p2 = java.lang.String('</p>'); s = readLine(br); while ~(s.startsWith(p1)) s = readLine(br); end
Display the text.
When you run this example, you see output similar to the following.
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