2. URLConnec@on
1. Obtain
a
new
HttpURLConnection
by
calling
URL.openConnection()
and
cas@ng
the
result
to
HGpURLConnec@on.
2. Prepare
the
request.
(URI)
3. Op@onally
upload
a
request
body
4. Read
the
response.
Response
headers
typically
include
metadata
such
as
the
response
body's
content
type
and
length,
modified
dates
and
session
cookies.
The
response
body
may
be
read
from
the
stream
returned
by
getInputStream().
5. Disconnect.
Once
the
response
body
has
been
read,
the
HttpURLConnection
should
be
closed
by
calling
disconnect().
Disconnec@ng
frees
all
resources
held
by
a
connec@on.
3. Fetching
URL
URL url = new URL("http://www.somesite.fi");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
String all = "";
int character;
while((character = stream.read()) != -1) {
all += (char) character;
}
urlConnection.disconnect();
4. Asynchronous
HGp
• It’s
wise
to
fetch
data
in
separate
thread
• Standard
Java
threading
model
can
be
used,
but
touching
the
UI
thread
is
forbidden
in
Android
• To
update
UI
from
background
task,
you
need
Android
specific
classes
like
Handler.
• AsyncTask
is
a
class
that
wraps
threading
and
handling
UI
thread
in
the
same
class.
(Hold’s
Handler)
7. Generic
Types
• The
three
types
used
by
an
asynchronous
task
are
the
following:
1. Params,
the
type
of
the
parameters
sent
to
the
task
upon
execu@on.
2. Progress,
the
type
of
the
progress
units
published
during
the
background
computa@on.
3. Result,
the
type
of
the
result
of
the
background
computa@on.
private class MyTask extends
AsyncTask<Void, Void, Void> { ... }
