The servlet programming question in Tc608--java

  
   
    servlet collation Author:lxy1. What is a servlet? Running in a servlet container, the server server directly parses the running Java application applet, 2. How to create a servlet essence: by inheriting or implementing an interface class and overriding the method. Step: [1]. Create a class that inherits HttpServlet (either implementing the Servlet interface or inheriting the Genericservlet Class) [2]. Overriding methods, Doget, Dopost, and so on (interfaces need to override all methods, However, the service method is processing the request) [3]. In the Web. xml file, configure
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    3.Servlet life cycle: Approximate process: [1]. Create a Servlet object and invoke the Init () method to initialize the Web with resource [2]. The service method is used to process the request [3]. Destroy servlet details with destroy: [1 ]. When a servlet is created, a Servlet object is created the first time the web is accessed, and the Init method is called, and a thread is invoked to invoke the service method, and Init is called only once [2]. When a second access is opened, a thread is invoked to invoke the service method to process the request [3]. The servlet resides in memory, and is typically created only once. [4]. If you create a member variable in a servlet to handle thread safety, try to avoid creating
   
  
  
   The relationship between the 
   
     4.Servlet interface and the Doget and Dopost methods in the HttpServlet class? [1]. When a servlet is accessed, the default service method processes the request, and the [2].service method is defined in the servlet, but the specific content is httpservlet in the [3]. In the service method of HttpServlet, Different methods are called according to the request method [4]. According to polymorphism, when calling Doget, Dopost, call the method of their own servlet supplement: template design mode: Public abstract class Car {public abstract void F IRE ();    Spark public abstract void run ();//Travel public abstract void Stop ();//stop//template public void Drive () {fire (); run (); Stop ();} }//The BMW class public class that inherits the Car interface BMW extends Car {@Overridepublic void Fire () {System.out.println ("BMW Fire");} @Overridepublic void Run () {System.out.println ("BMW Run");   @Overridepublic void Stop () {System.out.println ("BMW Stop");}    }//Test public class Test {public static void main (string[] args) {Car c = new BMW (); c.drive ();} }

   
  
  
   
    5. Know the folder in Tomcat: |-bin store startup, shutdown and other server programs |-conf store configuration information |-lib store the jar package |-logs store the log files |-temp the temporary files |-webapps storage deployment applications, There are several folders on the inside there are several applications |-web-inf |-classes Java class |-lib Java class run required jar package |-web.xml WAB app profile |-images pictures and other media File |-work Server working directory
   
  
  
   
    automatic loading of 6.Servlet: [1]. By adding <load-on-startup>2</load-on-startup> to the Web. xml file <servlet> tag
Create a servlet to follow the server startup [2]. function: Load resources [3]. The value of the tag is 1--10, the values are small and the priority is high, and the precedence is loaded in the configuration order. 
   
  
  
   
    url-pattern:[1 in 7.Servlet configuration]. Can a servlet map to multiple paths?
can [2].url-pattern] a. The exact match requirement must begin with "/" B. Directory match: Start with a "/" with a * end C. Extension matches: At the end of the *.xxx three priority: a > B > C; 
   
  
  
   
     path problems in 8.web development: [1]. How many ways does the browser access the server? A. browser address bar Enter URL B. Super Practice level <a href= "http://www.itheima.com" > Dark Horse </a> c. form <form action= "...." method= "POST" &G t;...</form>//Common request mode post get, except the form can post, the others are get d.javascript[2]. Access to the servlet path A. Absolute path: The |--band protocol is typically used to access out-of-site resources, developing infrequently With <a href= "http://www.baidu.com" > Baidu </a> |--without agreement to write a "/", equivalent to the server path, followed by the project name, plus the resource name can be used to access the resources in the station, development       Common <a href= "/day7_2/demo1" >demo1Servlet</a> equivalent: http://localhost:8080 B. Relative path: |--./xxx with the path to the second directory (project name) |-- .. /xxx return to the previous level to find the target conclusion: the use of absolute path without protocol "/value of Engineering name/servlet-pattern" is recommended in development 
   
  
  
   The Init method in the 
   
     9.Servlet interface: [1]. Why is the Init method in the Servlet interface parameterized and the method we are overriding has no parameters? |--the init (servletconfig config) method is overridden in the parent class , the method we override is not a method in the interface but is defined in its parent class [2]. What is servletconfig and what does it do? The |--servletconfig object represents the configuration object of the servlet, created by the server, and each servlet has its own ServletConfig object, which is not public |--    function: public void init (ServletConfig config) throws servletexception {this.config = Config;this.init ();} |---Get initialization parameters when a servlet is first accessed, a ServletConfig object is created and passed to the servlet through the Init method, so we can get its configuration information in the Servlet |---    You can get the name of the servlet to get the ServletConfig object: This.getservletconfig ();   |---can get the common API for ServletContext object servletconfig: |--public String getservletname (); Used to get the servlet name |--public string getinitparameter (string name); Used to get the value specified in Init-parent |--public enumeration Getinitparameter (String name);  Used to get all the name names in the Init-param |--public Servlet servletcontext getservletcontext (); Used to get a ServletContext object 
   
  
  
   
    10. About ServletContext objects [1]. ServletContext represents a Web application [2]. Gets the ServletContext object servletconfig. Getservletconfig (); [3]. function: A. Get global initialization parameters string Getinitparameter (string name) enumeration Getinitparameternames () You can configure global initialization parameters in the Web. xml file <context-param><param-name>name</param-name>vparam-value>tom</param-value></ Context-param> This configuration is for the entire web App B. Let the servlet implement information sharing ServletContext is a domain object (equivalent to a map, which is used throughout the Web application) C. Can get Path (Resource) *-* in W In EB Development, an absolute disk path must be used to obtain resources. Example Summary: 1.web does not access files other than MyEclipse Webroot, deployment only content in this file will be deployed into the server
   
    

The servlet programming question in Tc608--java