Head First Servlets And Jsp Pdf
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- Head first servlets and jsp 3rd edition pdf
- Head First Servlets and JSP, 2nd Edition
- Head First Servlets and JSP
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Head first servlets and jsp 3rd edition pdf
This page highlights the main things covered in Chapter 2: the servlet lifecycle, the role of the Container, and the Model-View-Controller design pattern. If you haven't encountered "design patterns" before, the following quotes from the book J2EE Design Patterns cited below may help set the right context for "design patterns" as we will use them in this course:.
A design pattern is a recurring solution to a recurring problem Good patterns strike a balance between the size of the problem they solve and the specificity with which they address the problem. The simplest patterns may be summed up in no more than a sentence or two. Using a database to store information for a web site is a pattern, albeit a fairly high-level and obvious one.
More complex patterns require more explanation We hope that readers will have two reactions as they explore the patterns in this book. The first is to say, "That's cool" or, if the boss is around, "That's useful! The second is to say, "So, what's the big deal? Design patterns in enterprise applications can be surprisingly simple on the surface. Of course, it's that generic aspect that makes them effective patterns in the first place.
I would also recommend looking over the Wikipedia entry on " design pattern computer science ". As in Chapter 1 , the objectives covered in Chapter 2 are also covered in more detail in later chapters.
Nevertheless, look this page over before you read Chapter 2. We'll be working with Tomcat all semester, and perhaps with Resin as well. So it is important to understand what Tomcat and Resin are. They are both examples of "Servlet Containers". Furthermore, Servlets can only exist inside a "Servlet Container". The container gives birth to servlets, supports them throughout their little lives, and takes care of them as they die. Pages cover the basics of what a Servlet Container is, and how a servlet interacts with the Container.
Read carefully, because this material will likely lead to some CISC midterm or final exam questions. Understanding about containers is also fundamental to understanding how to work with web applications composed of Servlets and later, also, JSPs.
This page asks you to speculate about what kinds of thing the Container must be doing for a Servlet. Skim through Chapter 1 again, and think about what happens when you run the example servlet from Chapter 1. The idea is to think about everything that is going on that is NOT in the code you wrote for your servlet; those are all the things that the Container must be doing for you.
It will really help your learning if you actually make the list and don't just cheat by looking at the answers at the bottom of the page. That "interactive reading style" is what the Head-First approach to textbooks is all about read over the preface on pages xxi through xxvii if you haven't done so yet; read about the Tiger and what it has to do with learning about Servlets. This page is an important list, so spend some time on it. These are all the things you don't have to worry so much about because of the help the Container gives you.
Pay particular attention to when the request and response objects get created, and when the thread starts running and when it stops running. Also note when the doGet or doPost methods get called. When you write code for webapps, these are all things you have to keep in mind if you want your code to work. The book notes that Without citing probably made up statistics, Sebesta agrees: "Most user-written servlets are extensions to HttpServlet" p. The diagram on pp.
Again, you should try to speculate about the answer before you turn the page; you are being asked on this page to answer a question that you have not yet been given the answer to. That's what the "Flex Your Mind" activities are all about. You should feel a bit of panic as you have to grasp at straws a bit and really think. That gets your brain juices flowing so that when you turn the page, what you read is more liable to stick to your brain all those brain juices make your brain stickier.
The explanation of this concept continues onto pages 47 through 49, so read all of these pages together. The character on this page the woman with her hands on her hips is one of my favorite characters in the Head-First books.
Unfortunately, she doesn't have a name; "Bob" and "Kim" get names, but this lady is without moniker. What I like is that she introduces some drama into what could be otherwise very dry material. Whenever she shows up, be sure to read her "thought bubble" usually brimming with attitude and sarcasm and the response. Imagine whether you think she would be satisfied with the answer, or just roll her eyes and say "what-ever!
On a serious note, the content on this page goes along with that on page 46, and as you already know, the content on p. And she's one of my favorite characters in the book. Do I need to spell it out for you? Check the confirmed errata for this page. Compare the code on this page with the web. Can you see how the material on p. Remember that each page contains a lot of content; the way it is laid out may cause you skim over some parts. Hopefully this builds some suspense and makes you want to read on just eight and a half chapters to get through first!?
The story sets the stage for you to ask a lot of questions on p. The answers to these questions don't come until Chapter 14, almost at the very end of the book pages , and the answers have something to do with the web development framework called "Struts". I'm told by students who have graduated and are in the so-called "real world" building "real web apps" and making "real money", that using "Struts" is very cool.
Knowing Struts can also get you a job at another company with a promotion and a pay raise when you get sick of your boss. So, if you hope to be able later to understand "Struts" and why it is a cool thing, it may help to spend some time on this story now. Look over Bob's design. Also look at his template code. Does it make sense to you? Try to understand it completely before you turn the page, and also see if you can find anything about it that you don't like.
Note one thing we haven't covered yet is how step "5" occurs—that is, if you want to:. For now, don't let that detail bother you; assume that it can be done in a straightforward way. The text covers the details of that in Chapter 3, pages 88 and 89, but you don't need to look over those now; it will just interrupt the flow of the story. This page puts the whole MVC thing in a context by adding some "human drama", i. If you are familiar and comfortable with MVC, this will immediately make sense to you, and you'll know exactly what Kim is talking about.
If you are new to MVC or rusty read this over, and then after you've read through pages , and later Chapter 3 Mini-MVC-Tutorial , come back and read this page again. Kim's comments will probably make a lot more sense then. This page introduces Model-View-Controller.
Get the big picture from this page, but if it is still murky, don't worry; Chapter 3 is an entire chapter called "Mini-MVC-Tutorial". MVC is so important, that some geeks have even been moved to song: lyrics mp3 So, is this what MVC is all about? What do you think of this design? On the next page, Kim is going to take a look hint: Kim is not going to like it. What do you think Kim will criticize? This is the biggest Flex Your Mind question in the whole book, in some sense, because the answer doesn't come until almost the very last page.
The first time you encounter this Flex Your Mind question, you probably aren't really ready to think in too much detail about it, because unless you've written MVC based servlets before, you don't have a really good idea about what "duplicate code" Bob and Kim are talking about. So my advice is, think about this for a few minutes now, but not too long. Check the confirmed errata for these pages!
Typically, you'll be creating a Deployment Descriptor by copying an existing one as a template, so you'll get all that for free anyway. However, if you are the type or person that wants to understand the details, you can learn a bit more about what all this means by reading up on XML namespaces in Sebesta. Of course, you probably will need to read Sections 8. Better, yet, just take this on faith for now, and don't worry about it for now. So, spend some time trying to understand these relationships, even if it seems like something that you won't really need to complete the programming assignments in this course.
To be honest, it isn't.
Head First Servlets and JSP, 2nd Edition
This page highlights the main things covered in Chapter 2: the servlet lifecycle, the role of the Container, and the Model-View-Controller design pattern. If you haven't encountered "design patterns" before, the following quotes from the book J2EE Design Patterns cited below may help set the right context for "design patterns" as we will use them in this course:. A design pattern is a recurring solution to a recurring problem Good patterns strike a balance between the size of the problem they solve and the specificity with which they address the problem. The simplest patterns may be summed up in no more than a sentence or two. Using a database to store information for a web site is a pattern, albeit a fairly high-level and obvious one.
Why use Servlets & JSPs? Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: Publisher: O'Reilly. Prepared for Stephen.
Head First Servlets and JSP
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Looking to study up for the new J2EE 1. This book will get you way up to speed on the technology you'll know it so well, in fact, that you can pass the brand new J2EE 1.
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