URLConnections - Java Network Programming - page 211

if you want to retry authorization—then getInputStream() will throw a ProtocolEx
ception .
Figure 7-1. An authentication dialog
The static methods getDefaultAllowUserInteraction() and setDefaultAllowUser
Interaction() determine the default behavior for URLConnection objects that have not
set allowUserInteraction explicitly. Because the allowUserInteraction field is
static (i.e., a class variable instead of an instance variable), setting it changes the default
behavior for all instances of the URLConnection class that are created after setDefaul
tAllowUserInteraction() is called.
For instance, the following code fragment checks to see whether user interaction is
allowed by default with getDefaultAllowUserInteraction() . If user interaction is not
allowed by default, the code uses setDefaultAllowUserInteraction() to make allow‐
ing user interaction the default behavior:
if (! URLConnection . getDefaultAllowUserInteraction ()) {
URLConnection . setDefaultAllowUserInteraction ( true );
}
protected boolean doInput
A URLConnection can be used for reading from a server, writing to a server, or both.
The protected boolean field doInput is true if the URLConnection can be used for read‐
ing, false if it cannot be. The default is true . To access this protected variable, use the
public getDoInput() and setDoInput() methods:
public void setDoInput ( boolean doInput )
public boolean getDoInput ()
For example:
try {
URL u = new URL ( "http://www.oreilly.com" );
URLConnection uc = u . openConnection ();
if (! uc . getDoInput ()) {
uc . setDoInput ( true );
}