I'm attempting to make a library with methods in a class that represent HTTP methods, such as GET, POST, and DELETE. I'm trying to do this with an abstract class that defines methods for each of these HTTP methods.
The problem comes in when I define a simple delete method for this class. This is what said method looks like:
/**
* A generic responder to a DELETE request.
*/
Response delete(Request request)
{
return new Response("Method not supported");
}
This should work fine in theory, but on compilation I get the error, no identifier for declarator Response.
Why is this error occurring? Removing the delete method makes the program compile, but having that one method in there makes it not compile at all.
Any help would be appreciated, thank you!
It is common practice to postfix keywords with underlines to be able to use them as variable names. See https://dlang.org/dstyle.html - Keywords
Related
We have following code structure in our code
namedParamJdbcTemplate.query(buildMyQuery(request),new MapSqlParameterSource(),myresultSetExtractor);
and
namedParamJdbcTemplate.query(buildMyQuery(request),new BeanPropertySqlParameterSource(mybean),myresultSetExtractor);
How can I expect these method calls without using isA matcher?
Assume that I am passing mybean and myresultSetExtractor in request for the methods in which above code lies.
you can do it this way
Easymock.expect(namedParamJdbcTemplateMock.query(EasyMock.anyObject(String.class),EasyMock.anyObject(Map.class),EasyMock.anyObject(ResultSetExtractor.class))).andReturn(...);
likewise you can do mocking for other Methods as well.
hope this helps!
good luck!
If you can't use PowerMock to tell the constructors to return mock instances, then you'll have to use some form of Matcher.
isA is a good one.
As is anyObject which is suggested in another answer.
If I were you though, I'd be using Captures. A capture is an object that holds the value you provided to a method so that you can later perform assertions on the captured values and check they have the state you wanted. So you could write something like this:
Capture<MapSqlParameterSource> captureMyInput = new Capture<MapSqlParameterSource>();
//I'm not entirely sure of the types you're using, but the important one is the capture method
Easymock.expect(namedParamJdbcTemplateMock.query(
EasyMock.anyObject(Query.class), EasyMock.capture(captureMyInput), EasyMock.eq(myresultSetExtractor.class))).andReturn(...);
MapSqlParameterSource caughtValue = captureMyInput.getValue();
//Then perform your assertions on the state of your caught value.
There are lots of examples floating around for how captures work, but this blog post is a decent example.
Am facing an issue while trying to implement an example given over a website.
One of the methods in a class has a signature like this -
private void updateTable(JsArray prices) {....}
And am trying to invoke this method from another method as -
updateTable(JsonUtils.safeEval(response.getText()));
while doing this am seeing a compilation error as -
The method updateTable(JsArray) in the type StockWatcher is not applicable for the arguments (JavaScriptObject)
Though I have just used the exact code displayed in the website, am seeing this error. Not sure what needs to be done. Please help.
The problem has been fixed by making the following change -
updateTable((JsArray)JsonUtils.safeEval(response.getText()));
introduced a casting in the above statement.
I am digging deep into the Zend framework and at this point I am a little confused. I am particularly checking out the Zend_Controller_Action (*_Action), Zend_Controller_Request_HTTP(*_HTTP) and Zend_Controller_Request_Abstract (*_Abstract).
The *_Abstract class as it's name suggests is an abstract class hence cannot be instantiated and mostly provides method stubs along with a few final implementations. The actual implementation is in *_HTTP and *_Simple classes that subclass *_Abstract. Fair enough.
Now I am looking at the *_Action class, right here: http://framework.zend.com/apidoc/1.0/Zend_Controller/Zend_Controller_Action.html
Taking a look at $_request variable, it states that it is an instance of type *_Abstract. At this point, I am confused since I do not know why it should be of type *_Abstract and not *_Http since one cannot technically have an instance of an abstract class.
So my question:
Why is an instance of an abstract class being declared here.
Moving on, I want to override the $_request classes's getParams() method since this is how our application retrieves all parameters and I would like to apply some common sanitization and blacklisting rules to all of our input right here.
Unfortunately, when in my BaseController (the Main Controller that is subclassed by all other controllers) I declare something to the effect of :
$_request = new RequestClass(); //RequestClass subclasses Zend_Controller_Request_Http and overrides getParams()
my application does not launch itself the way it ought (I get a blank screen).
For those more curious, RequestClass() getParams() does nothing fancy but:
getParams()
{
$params = parent::getParams();
//sanitization rules over $params;
return $params;
}
The type hint of Zend_Controller_Request_Abstract effectively means the request must be an instance of a class that extends Zend_Controller_Request_Abstract.
Unless you're delibrately not using ZF's routing, you'll probably be better off doing your sanitation of parameters through the routes. Otherwise, if you're getting a blank screen, that means display_errors is turned off and the PHP error or exception is being logged instead. Check your web server error log to see what the actual problem is.
Hi I am trying to learn JAVA deeply and so I am digging into the JDK source code in the following lines:
URL url = new URL("http://www.google.com");
URLConnection tmpConn = url.openConnection();
I attached the source code and set the breakpoint at the second line and stepped into the code. I can see the code flow is: URL.openConnection() -> sun.net.www.protocol.http.Handler.openConnection()
I have two questions about this
First In URL.openConnection() the code is:
public URLConnection openConnection() throws java.io.IOException {
return handler.openConnection(this);
}
handler is an object of URLStreamHandler, define as blow
transient URLStreamHandler handler;
But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right? But there are a lot classes who implement this methods in sun.net.www.protocol (like http.Hanlder, ftp.Handler ) How should the code know which "openConnection" method it should call? In this example, this handler.openConnection() will go into http.Handler and it is correct. (if I set the url as ftp://www.google.com, it will go into ftp.Handler) I cannot understand the mechanism.
second. I have attached the source code so I can step into the JDK and see the variables but for many classes like sun.net.www.protocol.http.Handler, there are not source code in src.zip. I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip? Where can I find a comprehensive version of source code?
Thanks!
First the easy part:
... I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip?
Two reasons:
In the old days when the Java code base was proprietary, this was treated as secret-ish ... and not included in the src.zip. When they relicensed Java 6 under the GPL, they didn't bother to change this. (Don't know why. Ask Oracle.)
Because any code in the sun.* tree is officially "an implementation detail subject to change without notice". If they provided the code directly, it helps customers to ignore that advice. That could lead to more friction / bad press when customer code breaks as a result on an unannounced change to sun.* code.
Where can I find a comprehensive version of source code?
You can find it in the OpenJDK 6 / 7 / 8 repositories and associated download bundles:
http://hg.openjdk.java.net/jdk6/jdk6 - http://download.java.net/openjdk/jdk6/
http://hg.openjdk.java.net/jdk7/jdk7 - http://download.java.net/openjdk/jdk7/
http://hg.openjdk.java.net/jdk8/jdk8
Now for the part about "learning Java deeply".
First, I think you are probably going about this learning in a "suboptimal" fashion. Rather than reading the Java class library, I think you should be reading books on java and design patterns and writing code for yourself.
To the specifics:
But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right?
At the point that the handler calls than method, it is calling it on an instance of the subclass. So finding the right method is handled by the JVM ... just like any other polymorphic dispatch.
The tricky part is how you got the instance of the sun.net.www.protocol.* handler class. And that happens something like this:
When a URL object is created, it calls getURLStreamHandler(protocol) to obtain a handler instance.
The code for this method looks to see if the handler instance for the protocol already exists and returns that if it does.
Otherwise, it sees if a protocol handler factory exists, and if it does it uses that to create the handler instance. (The protocol handler factory object can be set by an application.)
Otherwise, searches a configurable list of Java packages to find a class whose FQN is package + "." + protocol + "." + "Handler", loads it, and uses reflection to create an instance. (Configuration is via a System property.)
The reference to handler is stored in the URL's handler field, and the URL construction continues.
So, later on, when you call openConnection() on the URL object, the method uses the Handler instance that is specific to the protocol of the URL to create the connection object.
The purpose of this complicated process is to support URL connections for an open-ended set of protocols, to allow applications to provide handlers for new protocols, and to substitute their own handlers for existing protocols, both statically and dynamically. (And the code is more complicated than I've described above because it has to cope with multiple threads.)
This is making use of a number of design patterns (Caches, Adapters, Factory Objects, and so on) together with Java specific stuff such as the system properties and reflection. But if you haven't read about and understood those design patterns, etcetera, you are unlikely to recognize them, and as a result you are likely to find the code totally bamboozling. Hence my advice above: learn the basics first!!
Take a look at URL.java. openConnection uses the URLStreamHandler that was previously set in the URL object itself.
The constructor calls getURLStreamHandler, which generates a class name dynamically and loads, and the instantiates, the appropriate class with the class loader.
But URLStreamHandler is a abstract class and method openConnection()
is not implement in it so when handler calls this method, it should go
to find a subclass who implement this method, right?
It has to be declared or abstract or implemented in URLStreamHandler. If you then give an instance of a class that extends URLStreamHandler with type URLStreamHandler and call the openConnection() method, it will call the one you have overriden in the instance of the class that extends URLStreamHandler if any, if none it will try to call the one in URLStreamHandler if implemented and else it will probably throw an exception or something.
I've seen this question regarding partial stubs, but it does not quite tell me what I need to know.
I understand that, if I am using a Moles stub for a class (let's say, for DataService, I'm using SDataService), I can set the CallBase property to true so that, if there is no delegate for a particular method, the base implementation's method will be called. Great, but how do I assign a delegate to a particular method in this case?
If there is no way to do that, say I have an interface IDataService that I stub using SIDataService. I can easily assign a delegate to a method here. But, how do I tell it to call the corresponding method on DataService (an implementation of IDataService) if there is no delegate for a given method?
Thank you!
Edit:
I see now that the method needs to be virtual to be overridden in the first scenario above. I don't think that makes a whole lot of sense, but it is what it is.
So, focusing on the second scenario, would I have to create a Behavior? (And why isn't there one already for stubs like there is for moles?) Or is there a simpler way?
Delegates (detours) are set to stubs types the same way as mole types. For example, SIDataService.GetMemberProfile() is configured to return a mock object like this:
var memberMock = new Member() { Firstname="Joe", LastName="Schmoe" };
var stub = new SIDataService();
stub.GetMemberProfileMember = i => memberMock;