URLConnections - Java Network Programming - page 208

load a fixed set of files at launch time and then only serve those out of memory. This
might be useful for a server that processes many different SOAP requests, all of which
adhere to a few common schemas that can be stored in the cache. The abstract
ResponseCache class is flexible enough to support all of these and other usage patterns.
Configuring the Connection
The URLConnection class has seven protected instance fields that define exactly how the
client makes the request to the server. These are:
protected URL url ;
protected boolean doInput = true ;
protected boolean doOutput = false ;
protected boolean allowUserInteraction = defaultAllowUserInteraction ;
protected boolean useCaches = defaultUseCaches ;
protected long ifModifiedSince = 0 ;
protected boolean connected = false ;
For instance, if doOutput is true , you'll be able to write data to the server over this
URLConnection as well as read data from it. If useCaches is false , the connection by‐
passes any local caching and downloads the file from the server afresh.
Because these fields are all protected, their values are accessed and modified via obvi‐
ously named setter and getter methods:
public URL getURL ()
public void setDoInput ( boolean doInput )
public boolean getDoInput ()
public void setDoOutput ( boolean doOutput )
public boolean getDoOutput ()
public void setAllowUserInteraction ( boolean allowUserInteraction )
public boolean getAllowUserInteraction ()
public void setUseCaches ( boolean useCaches )
public boolean getUseCaches ()
public void setIfModifiedSince ( long ifModifiedSince )
public long getIfModifiedSince ()
You can modify these fields only before the URLConnection is connected (before you
try to read content or headers from the connection). Most of the methods that set fields
throw an IllegalStateException if they are called while the connection is open. In
general, you can set the properties of a URLConnection object only before the connection
is opened.
There are also some getter and setter methods that define the default behavior for all
instances of URLConnection . These are:
public boolean getDefaultUseCaches ()
public void setDefaultUseCaches ( boolean defaultUseCaches )
public static void setDefaultAllowUserInteraction (
boolean defaultAllowUserInteraction )