7 Step of working process of servlet-
step 1-client request to server for any servlet.
step 2-server finds that servlet using servlet-mapping and create 2 objects,
(a)request object- for servlet
(b)response object-for client
step 3- server calls service method in new thread and pass request and response objects as argument.
step 4-service method calls doPost() if request from client is POST else doGet().
step 5- servlet provide output in response object to server.
step 6-Server passes response object to client.
step 7- thread dies, garbage collection.
-Block Diagram –
Example 1-Web app to call a servlet to print “java is simple” from a html page.
Output-
Project Structure-
-3 Files-
1-XYZ.java(inside package ‘abc’)
2-web.xml(inside WEB-INF folder)
3-index.html(inside WebContent folder)
1-XYZ.java (servlet)
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package abc;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;public class XYZ extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {PrintWriter out = response.getWriter();out.print("java is simple");}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}} |
2-web.xml (deployment descriptor)
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<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"><display-name>FirstWeb</display-name><welcome-file-list><welcome-file>index.html</welcome-file></welcome-file-list><servlet><servlet-name>a</servlet-name><servlet-class>abc.XYZ</servlet-class></servlet><servlet-mapping><servlet-name>a</servlet-name><url-pattern>/pqr</url-pattern></servlet-mapping></web-app> |
3-index.html
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<html><body><a href="pqr">click here</a></body></html> |
