java servlets and jsp

configuration in Assigning values to Objects Provided ServletConfig when the servlet was first initialized Provided ServletContext when the servlet was first initialized To initialize the parameters Servletcontextlistener (Context Listener)Servletcontextlistener is able to listen to a context initialization event so that it can get context parameters and run some code before the app provides services to the customer.Just as you tell the Web container

Servlets and jsp (preferred for SUN Enterprise Applications) Development Principles (II) Do not re-invent the wheel. Do not start from scratch: Custom components can improve reusability, but custom components still need to write, test, and Debug programs. The problem is that someone else may have done this, and your implementation method is not necessarily better than others. This isJsp (prefer

unconsciously mix the presentation layer and business layer. Just like the previous friend who put the database processing information in JSP, in fact, it should be placed in the business layer. According to SUN's recommendation, JSP should only store the content related to the presentation layer, that is, only the part of the HTML webpage is output. All data computing, data analysis, and database connecti

). 　　 　　 What are the implied objects (Implicity object) in the JSP page? What are their respective types and functions? 　　 Request-- Reponse-- Session-- Application-- Out-- Page-- PageContext-- Exception-valid only if the current JSP page is the error page. Config-- 　　 　　 What is the difference between the 　　 　　 　　 servlets/

; Servlet-class>Com.example.ListenerTesterServlet-class> servlet> servlet-mapping> Servlet-name>ListenertesterServlet-name> Url-pattern>/listenertester.doUrl-pattern> servlet-mapping> Web-app> packagecom.example;Importjavax.servlet.ServletContext;Importjavax.servlet.ServletContextEvent;Importjavax.servlet.ServletContextListener; public class Myservletcontextlistener ImplementsServletcontextlistener {@Override public voidcontextinitialized (servletcontextevent serv

client. Resp),doPost (httpservletrequest req, HttpServletResponse resp) such as The servlet responds to the customer by responding to the object, and the container returns the response to the customer. The service () thread ends, retains or cleans up the responding object, and the customer gets a response. 3. Mark Tomcat Official document Servlet API documentation4, HttpServlet inheritance tree, interface Java.lang.Object Javax.servlet.GenericServletJavax.servlet.http

Servlet and JSP Technology is the Java Development Server-side application of the main technology, is the development of business applications, the standard of the presentation end. Java developers like to use it for a variety of reasons, one is familiar with the Java language developers are easy to learn the technolog

;Importjavax.servlet.*;Importjava.io.IOException; Public classFilterImplementsjavax.servlet.filter{Private intvisited; @Override Public voidInit (Filterconfig filterconfig)throwsservletexception {} @Override Public voidDoFilter (ServletRequest servletrequest, Servletresponse servletresponse, Filterchain filterchain)throwsIOException, servletexception {servletresponse.setcontenttype ("Text/html"); Servletresponse.setcharacterencoding ("Utf-8"); Visited++; Filterchain.dofilter (ServletReque

Java ServletTechnology andJSP TechnologyWith the Java server technology, they currently control the entire server-side Java technology market and gradually become the standard for building commercial Web applications. Java developers like these technologies for many reasons, including: these technologies are easy to le

Let other components take over all requests; Partial takeover requestSome questions--The Intercept point is useful.1. Let other components take over all requests. PackageCom.example.web;ImportCom.example.model.BeerExpert;Importjavax.servlet.*;Importjavax.servlet.http.*;ImportJava.io.*;ImportJava.util.*; Public classBeerselectextendsHttpServlet {@Overrideprotected voidDoPost (httpservletrequest req, HttpServletResponse resp)throwsservletexception, IOException {String C= Req.getparameter ("Color")

First of all, spit groove yourself, old remember the wrong spelling of the word servlets ~ ~ ~At head first Servlets jsp, I felt the fascination of head first (multi-image, one-page-less, this is head).What did the 1.WEB server do for you?Web browser----(the user's request contains the name and address URL of the resource the user is looking for)---> RequestServe

Declaring a generic error pageThis applies to all resources in the Web app, not just the JSP A more explicit exception error declaration Declaring error page based on HTTP status code Configuring servlet initialization in DDThe servlet is initialized by default when the first request arrives, and you can set the Load-on-startup element if you want to load the servlet when the deployment or server restarts.If multiple elements ar

is not serializable? For migration, the Property object class needs to be httpsessionactivationlistener and the activation/deactivation callback method is used to solve the problem. Listener Example Session counterThis listener allows you to track the number of active sessions in this web app:To configure listeners in DD:Attention: Attribute Supervisor ListenerThis listener can be traced every time a property is added to a session, a property is deleted, or a property is repla

type first, and then change to another type to continue writing.6. Why should I return a file through a servlet instead of returning it directly? The reason is that you want to perform some logic before and after returning a specific type of file, such as determining whether the user has permission to download the file.7, some things to remember, about the output, there are only two choices: characters or bytes.Output streams that can be returned via resp ... /* Omit parameter */ // can

Cookie ("userid", UserID); Resp.addcookie (cookie);Once the cookie is sent from the server side to the client, there is no way for the server side to display the cookie deletion. However, a substantial deletion of the client cookie can be achieved by overwriting the expired cookie.New Cookie ("userid", UserID), Cookie.setmaxage (0); Resp.addcookie (cookie) ;Chinese charactersIf the contents of a cookie are Chinese characters, you need to encode it:String username = java.net.URLEncoder.encode ("

shown below (click to view larger image):Click on the network, you can observe a header named Loction, the content is exactly the URL we redirect, then if the servlet code is changed to "Resp.setheader (" Location "," http://www.cnblogs.com/xkxf/"); Can I implement redirection? The answer is no, but add the words "resp.setstatus (302);" It is possible to achieve this effect.7. Finally, what does Sendredirect ("another URL") mean? The explanation in the book is that you want the browser to proce