Implementing the CookieHandler.get Method
The get method is a little more complex that the put method.
One argument of the get method is the Map object, requestHeaders. This object contains the headers that must be sent to the accessed URI. The problem is that this object doesn't contain the "Cookie" header—you need to attach that manually, but only after you populate it with the right cookies. To do this, copy the requestHeaders, then populate the copy, set is as read-only and return it (notice that the get method returns a Map object). This little trick is necessary because requestHeaders is set to read-only, so it can't be modified.
Before you extract the appropriate cookies from the myCookieBriefcase list, you have to do some clean up work and delete all the expired cookies. First, you need to determine which cookies are expires. Iterate over the list and call the ExpireState method from the Cookie class—this will tell you if a cookie is expired. If the cookie is expired, delete it by calling the remove method. Next, select the right cookies for the current URI. Every selected cookie is added into a string and separated from the others by "; ". Selection is made by the MatchState method from the Cookie class.
//implementing the get method
public Map<String, List<String>> get(URI uri,Map<String,
List<String>> requestHeaders)throws IOException {
//keep a copy of requestHeaders
Map<String, List<String>> setCookies = new HashMap<String,
List<String>>(requestHeaders);
StringBuilder selectCookies=new StringBuilder();
ListIterator myCookieBriefcase_iterator=myCookieBriefcase.listIterator();
while(myCookieBriefcase_iterator.hasNext())
{
Cookie cookie=(Cookie)myCookieBriefcase_iterator.next();
//delete all the expired cookies
if(cookie.ExpireState())
{
myCookieBriefcase.remove(cookie);
}
//verify if the current cookie coresponds to the accessed URI
else if(cookie.MatchState(uri))
{
if(selectCookies.length()>0)
{
//cookies are separated by ", "
selectCookies.append(", ");
}
selectCookies.append(cookie.toString());
}
}
Next, convert the string of cookies into a List object. After that, add the List object to the Map object, setCookies. Before you return it, set it as read-only:
//converting the StringBuilder object, selectCookies,to a List object
if(selectCookies.length()>0)
{
List<String>
finalCookies=Collections.singletonList(selectCookies.toString());
setCookies.put("Cookie",finalCookies);
}
System.out.println("###"+setCookies+"###");
//set the setCookies as read-only
Collections.unmodifiableMap(setCookies);
//returning the headers list
return(setCookies);
}
}
You've finally completed the first step in developing a cookie manager. The second step is to develop the Cookie class, which is responsible for parsing cookies to extract clean information, domains, paths, and expiration dates. Listing 4 shows the Cookie class.
The Cookie class has three important methods:
-
ExpireState: This verifies if a cookie has expired.
//verify if the current cookie has expired
public boolean ExpireState()
{
if(this.expire_date==null)
{
return false;
}
Date today=new Date();
boolean aft=today.after(expire_date);
return aft;
}
-
MatchState: This verifies if a cookie corresponds to the current URI.
//verify if the current cookie coresponds to the URI
public boolean MatchState(URI uri)
{
if (ExpireState())
{
return false;
}
String path=uri.getPath();
if (path==null)
{
path = "/";
}
if(path.startsWith(this.path))return true;
return false;
}
-
toString: This returns the cookie information.
//returns the cookie inofrmation
public String toString()
{
StringBuilder SB=new StringBuilder(key);
SB.append(value);
return SB.toString();
}
It's time to test this cookie handler. To do this, you'll need to write a test class, like the TestMyCookieHandler class below. TestMyCookieHandler connects to the same resource twice, in this example, http://www.DevX.com. During the first connection, the manager extracts and stores the cookies. During the second connection, the manager provides the correct cookies to the requested URI.
System.out.println("\nFirst time\n");
url=new URL("http://www.DexX.com");
URLconn=url.openConnection(proxy);
Object content=URLconn.getContent();
System.out.println("\nSecond time\n");
url=new URL("http://www.DevX.com");
URLconn=url.openConnection(proxy);
content=URLconn.getContent();
Or for the http://www.google.com resource:
The next three listings compose the complete source code for the TestMyCookieHandler.java, MyCookieHandler.java, and Cookie.java applications:
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