HttpServletResponse resp throws ServletException, java. Why Web Pages Dynamically? Handles it by Thread. New process started for each process. Automatically parsing and You have to do yourself. Can communicate directly Requires server based with web server. Portable Not portable. Class java. Object Interface javax. Class Interface javax. GenericServlet javax. Interface Class javax. Serializable javax. Used to store the servlets startup configuration values and the initialization parameters.
Life Cycle of Servlets. Advantages of using doxxx over service. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Uploaded by api Did you find this document useful? Is this content inappropriate? Report this Document. Flag for inappropriate content. Download now. Introduction To Servlet. Original Title: Introduction to Servlet. Related titles. Carousel Previous Carousel Next.
Jump to Page. Search inside document. This is it. We know. Sometimes you need more than EL or standard actions. The JSTL 1. Having access to 9. JSTL v1.
URL-related: url. That means each web app needs a copy. I want to show one element per row in a table EL and standard actions are limited What happens when you bump into a brick wall? Developers usually want way more standard actions or—even better—the ability to create their own actions.
And you can. For the JSP page creator, custom tags are much easier to use than scripting. For the Java programmer, however, building the custom tag handler the Java code invoked when a JSP uses the tag is tougher.
Still, there could be times when you need something from, say, a custom tag library developed specifically for your company. What we need is a way to convert those angle brackets into something the browser will render as angle brackets, and there are two ways to do this. A c:out tag without an escapeXML attribute is just the.
She noticed that we were using EL everywhere to output strings entered by users. She said this was a security risk and recommended we output all user strings using the c:out tag. What gives? A: Your consultant was right. The security risk she is referring to is called cross-site hacking or cross-site scripting.
The cracker includes viral JavaScript code in the comment. This previnterpreted by A: Good question. The c:out tag is smart, and it recognizes when the value is null and can perform a special action. That action is to provide a default value Just add a default attribute, and provide the value you want to print if your expression evaluates to null: This value is output if the value attribute evaluates to null. Servlet code Mak e a St set the arrring[] of movie names, ay as a requ est attribuatnd e.
This table has element in a ne per row. The trick is telling the table how many rows and columns you want. The key feature is that the tag assigns each element in the collection to the variable you declare with the var attribute. The variab value changes with each iter collection.
An array of arrays? In this example, we put String arrays into an ArrayList, then make the ArrayList a request attribute. The JSP has to loop through the ArrayList to get each String array, then loop through each String array to print the actual elements of the array. ArrayList ; movieList. Watch it! No fou r— ibutes like the other book tells you where to get the specs covered on the to which you can bind attr ses sio n, and application.
Tag scope exam. And imagine that members can also post comments, but non-member guests cannot. What if you want to do one thing if the condition is true, and a different thing if the condition is false? In other words, what if we want to show either one thing or the other, but nobody will see both?
The first But now imagine this scenario: you have a car sales web site, and page asks the user what he you want to customize the headline that shows up on each page, based on a user attribute set up earlier in the session. We are, after all, trying to sell him a car the pages that talk about and become obscenely wealthy. Now you can stop even if you do st cu it his in t drive insanely fast.
We have the best speed sensors of any car this size. But what if you want to set a value in a Map? What if you want to make a new entry in a Map? Or what if you simply want to create a new request-scoped attribute? Set comes in two flavors: var and target. The var version is for setting attribute variables, the target version is for setting bean properties or Map values. Each of the two flavors comes in two variations: with or without a body. This happens even if start looking at pag e, a scope, it will Duck, or a Broccoli.
Even attribute. Q: Why would I use the body version instead of the no-body version? It looks like they both do exactly the same thing. It might be a long and complex is page scope. If you put in a String look in the page scope space. A: We hear you. Once again, nobody asked US. That feels wrong.
But remember, set does a remove only when you pass in a null value. The answers are at the end of the chapter. The include directive use you do have different word for the attribu s ma kes sen se, wh en you think about it The imported chunk uses a reference to an image that is also on Server B.
This is my horse. Welcome to our Web Services Support Group. How can you guarantee session tracking from a JSP He missed the point How can I get the session ID added to Ahhh It does URL rewriting automatically. First we had to get the session either the existing one or a new one. The Container wants to use a cookie—it wants to include a unique cookie with the response, and then the client will send that cookie back with each subsequent request. Except one problem Then what? Query stringacpaes, for example, Uh-oh You can design a custom page to handle errors, then use the page directive to configure it.
And what if I want a different error page depending on the error? You can declare error pages in the DD for the entire web app, and you can even configure different error pages for different exception types, or HTTP error code types , , etc.
That way you can show the client different error pages specific to the type of the problem that generated the error. Declaring a catch-all error page This applies to everything in your web app—not just JSPs. You can override it in individual JSPs by adding a page directive with an errorPage attribute.
The object is type java. Throwable, so in a script you can call methods, and with EL you can access the stackTrace and message properties. This time, you getabmly details. What if there are some errors I want to catch myself? The one that was actually thrown? But with web app error handling, remember, only officially-designated error pages get the exception object. It puts the exception object into the page scope, under the name you declare as the value of var.
Inside the catch. If you bod y. The point is—learn catch or finally block. And on the exam, fooled. The JSTL is huge. Version 1. But nsformation e. The XML tra give it the delimiter.
We have a whole chapter the next one devoted to developing your own custom tag handlers. But the last part of this chapter is about how to use custom tags. What happens, for example, if someone hands you a custom tag library they created for your company or project? How do you know what the tags are and how to use them? You have to know how to figure out a tag even if the yo documentation is weak or nonexistent, and, eed to Everything you n one more thing—you have to know how to deploy a custom tag library.
Main things you have to know: know is in there.
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