ServletConfig interface-
Definition- Servlet config is used to pass information to a servlet during initialization.
Step 1- Initialization of key-value pair in web.xml for particular servlet
Step 2-Access value using key in servlet
Example 5- Web app to create a servlet which gets data from web.xml using ServletConfig interface.
Output-
Project Structure-
3 files-
1-Zx.java(inside package=’ab’)
2-web.xml(inside WEB-INF folder)
3-index.html(inside WebContent folder)
1-Zx.java(servlet)-
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Zx extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletConfig sc=getServletConfig();
String a=sc.getInitParameter("myName");
PrintWriter out=response.getWriter();
out.print(a);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
2-web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1"> <display-name>Exconfig</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>q</servlet-name> <servlet-class>ab.Zx</servlet-class> <init-param> <param-name>myName</param-name> <param-value>Mr.Java</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>q</servlet-name> <url-pattern>/first</url-pattern> </servlet-mapping> </web-app>
3-index.html
<!DOCTYPE html> <html> <head> <meta charset="ISO-8859-1"> <title>Insert title here</title> </head> <body> <a href="first">Click here</a> </body> </html>
ServletContext Interface-
Definition-Used to get configuration information from Deployment Descriptor(web.xml).
-Available for all servlets or JSPs of the Web app.
Step 1- Initialization of key-value pair in web.xml for all servlets
Step 2-Access value using key in any servlet
Example 6- Web app to create any number of servlets which get data from web.xml using ServletContext interface.
Output-
Project Structure-
4 files-
1-Yz.java(inside package= ‘ab’)
2-Zx.java(inside package=’ab’)
3-web.xml(inside WEB-INF)
4-index.html(inside WebContent)
1-Yz.java(Servlet)
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Yz extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext sc = getServletContext();
String a= sc.getInitParameter("MyName");
PrintWriter out=response.getWriter();
out.print(a);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
2-Zx.java(servlet)
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Zx extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext sc = getServletContext();
String a= sc.getInitParameter("MyName");
PrintWriter out=response.getWriter();
out.print(a);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
3-web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1"> <display-name>ExCntxt</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <context-param> <param-name>MyName</param-name> <param-value>Mr.Java</param-value> </context-param> <servlet> <servlet-name>a</servlet-name> <servlet-class>ab.Yz</servlet-class> </servlet> <servlet-mapping> <servlet-name>a</servlet-name> <url-pattern>/first</url-pattern> </servlet-mapping> <servlet> <servlet-name>b</servlet-name> <servlet-class>ab.Zx</servlet-class> </servlet> <servlet-mapping> <servlet-name>b</servlet-name> <url-pattern>/second</url-pattern> </servlet-mapping> </web-app>
4-index.html
<!DOCTYPE html> <html> <head> <meta charset="ISO-8859-1"> <title>Insert title here</title> </head> <body> <a href="first">click here servlet1</a> <a href="second">click here servlet2</a> </body> </html>
