servlet Archives

How to access ServletContext parameters

August 26, 2023August 26, 2023 by manish

index.html

        <title>Servlet Context Example</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    
    

<h3>Servlet Context Example</h3>

        <a href="get-servlet-context">Call Servlet1</a>
        <a href="get-context">Call Servlet2</a>

<title>Servlet Context Example</title>

<h3>Servlet Context Example</h3>

<a href="get-servlet-context">Call Servlet1</a>

<a href="get-context">Call Servlet2</a>

web.xml

<!--?xml version="1.0" encoding="UTF-8"?-->
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <context-param>
        <param-name>SiteName</param-name>
        <param-value>Ebhor.com</param-value>
    </context-param>
    <servlet>
        <servlet-name>ServletContext</servlet-name>
        <servlet-class>ebhor.servlet.ServletContext</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>ServletContext1</servlet-name>
        <servlet-class>ebhor.servlet.ServletContext1</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletContext</servlet-name>
        <url-pattern>/get-servlet-context</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>ServletContext1</servlet-name>
        <url-pattern>/get-context</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">

<context-param>

<param-name>SiteName</param-name>

<param-value>Ebhor.com</param-value>

</context-param>

<servlet-name>ServletContext</servlet-name>

<servlet-class>ebhor.servlet.ServletContext</servlet-class>

</servlet>

<servlet-name>ServletContext1</servlet-name>

<servlet-class>ebhor.servlet.ServletContext1</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>ServletContext</servlet-name>

<url-pattern>/get-servlet-context</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>ServletContext1</servlet-name>

<url-pattern>/get-context</url-pattern>

</servlet-mapping>

<session-config>

<session-timeout>

</session-timeout>

</session-config>

</web-app>

ServletContext.java

package ebhor.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletContext extends HttpServlet {
   
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
       response.setContentType("text/html");
       String value=getServletContext().getInitParameter("SiteName");
       PrintWriter out=response.getWriter();
         out.println("At ServletContext servlet ");
       out.println("
<h2>Site Name is "+value+"</h2>
");
    }

   
}

package ebhor.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class ServletContext extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html");

String value=getServletContext().getInitParameter("SiteName");

PrintWriter out=response.getWriter();

out.println("At ServletContext servlet ");

out.println("

<h2>Site Name is "+value+"</h2>

");

}

ServletContext1.java

package ebhor.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class ServletContext1 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        String value = getServletContext().getInitParameter("SiteName");
        PrintWriter out = response.getWriter();
        out.println("At ServletContext1 servlet ");
        out.println("
<h2>Site Name is " + value + "</h2>
");
    }
}

package ebhor.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class ServletContext1 extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html");

String value = getServletContext().getInitParameter("SiteName");

PrintWriter out = response.getWriter();

out.println("At ServletContext1 servlet ");

out.println("

<h2>Site Name is " + value + "</h2>

");

}

Results

How to access ServletConfig initial parameter value

August 26, 2023August 26, 2023 by manish

java servlet are executed when user request for some resource in server. ServletConfig is interface defined in javax.servlet package. ServletConfig is used to access servlet’s initial value stored in web.xml. For each servlet there is one ServletConfig. Initial value for servlet are stored in web.xml with name value pair as follows

<servlet>
        <servlet-name>ServletName</servlet-name>
        <servlet-class>ServletClass</servlet-class>
        <init-param>
            <param-name>Param1</param-name>
            <param-value>Value1</param-value>
        </init-param>
      <init-param>
            <param-name>Param2</param-name>
            <param-value>Value2</param-value>
        </init-param>
        .......

    </servlet>
   <servlet-mapping>
        <servlet-name>ServletName</servlet-name>
        <url-pattern>/url-pattern</url-pattern>
    </servlet-mapping>

<servlet-name>ServletName</servlet-name>

<servlet-class>ServletClass</servlet-class>

<init-param>

<param-name>Param1</param-name>

<param-value>Value1</param-value>

</init-param>

<init-param>

<param-name>Param2</param-name>

<param-value>Value2</param-value>

</init-param>

.......

</servlet>

<servlet-mapping>

<servlet-name>ServletName</servlet-name>

<url-pattern>/url-pattern</url-pattern>

</servlet-mapping>

initial parameter are … Read more

Java Servlet Response JSON in JSP using Gson

August 13, 2023August 13, 2023 by manish

In Modern web applications, We get data from the server in JSON format and display data in JSP or HTML page using Front end library or frameworks like Angular, React, etc. This is similar to mobile app development. Here we will see how we can get JSON Response from the servlet and show it in … Read more

Submitting data to servlet using http post

November 22, 2023June 30, 2023 by manish

Data sent using http post method is not visible at browser address bar index.jsp

&lt;%@page contentType="text/html" pageEncoding="UTF-8"%&gt;
All the services of this website is free. Before using the services you have to register
Provide all details
Fname <input name="fname" type="text" placeholder="Enter your First Name" />
<span style="font-size: inherit; background-color: var(--base-3);">Lname </span><input name="lname" type="text" placeholder="Enter your Last Name" />
<span style="font-size: inherit; background-color: var(--base-3);">Mail Id </span><input name="mailId" type="text" placeholder="Enter your Mail Id" />
<span style="font-size: inherit; background-color: var(--base-3);">Mobile No </span><input name="mobileNo" type="text" placeholder="Enter your Mobile No" />
<span style="font-size: inherit; background-color: var(--base-3);">DOB </span><input name="dob" type="text" placeholder="Enter your Date of Birth" />
<input type="submit" value="Register" />

<%@page contentType="text/html" pageEncoding="UTF-8"%>

All the services of this website is free. Before using the services you have to register

Provide all details

Fname <input name="fname" type="text" placeholder="Enter your First Name" />

<span style="font-size: inherit; background-color: var(--base-3);">Lname </span><input name="lname" type="text" placeholder="Enter your Last Name" />

<span style="font-size: inherit; background-color: var(--base-3);">Mobile No </span><input name="mobileNo" type="text" placeholder="Enter your Mobile No" />

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = {"/register"})
public class Register extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            String name = request.getParameter("fname") + " " + request.getParameter("lname");
            String mailId = request.getParameter("mailId");
            String mobileNo = request.getParameter("mobileNo");
            String dob = request.getParameter("dob");
            out.println("");
            out.println("");
            out.println("");
            out.println("");
            out.println("");
            out.println("");
            out.println("Your Registration Detail");
            out.println("Name :" + name + "");
            out.println("Mail Id :" + mailId + "");
            out.println("Mobile No :" + mobileNo + "");
            out.println("Date of Birth :" + dob + "");
            out.println("");
            out.println("");
        } finally {
            out.close();
        }
    }
}

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = {"/register"})

public class Register extends HttpServlet {

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out = response.getWriter();

try {

String name = request.getParameter("fname") + " " + request.getParameter("lname");

String mailId = request.getParameter("mailId");

String mobileNo = request.getParameter("mobileNo");

String dob = request.getParameter("dob");

out.println("");

out.println("Your Registration Detail");

out.println("Name :" + name + "");

out.println("Mail Id :" + mailId + "");

out.println("Mobile No :" + mobileNo + "");

out.println("Date of Birth :" + dob + "");

out.println("");

} finally {

out.close();

}

Request dispatcher in Servlet User Login Example

September 28, 2023June 30, 2023 by manish

Request dispatcher in Servlet is one of the important topics here we explained it using the User login example. In Java Servlets, a RequestDispatcher is an interface provided by the Servlet API that allows you to forward or include a request or response from one servlet to another servlet, JSP (JavaServer Pages), or any other … Read more

Getting parameter values in Servlet getParameterNames

November 22, 2023June 30, 2023 by manish

Project Explorer : index.jsp

&lt;%@page contentType="text/html" pageEncoding="UTF-8"%&gt;
Getting all parameter values in servlet  
<b>Name:</b>
<input name="name" type="text" placeholder="Enter your  name" />
<b>Contact No:</b>
<input name="contactNo" type="text" placeholder="Enter your  contact no" />
<input name="contactNo" type="text" placeholder="Enter your  contact no" />
<input name="contactNo" type="text" placeholder="Enter your  contact no" />
<input name="contactNo" type="text" placeholder="Enter your  contact no" />
<b>Email:</b>
<input name="email" type="email" placeholder="Email address" />
<input name="email" type="email" placeholder="Email address" />
<input name="email" type="email" placeholder="Email address" />
<input name="email" type="email" placeholder="Email address" />
<b> Web site</b>
<input name="website" type="url" placeholder="Website" />
<input name="website" type="url" placeholder="Website" />
<input name="website" type="url" placeholder="Website" />
<input name="website" type="url" placeholder="Website" />
<input type="submit" value="Submit" />

<%@page contentType="text/html" pageEncoding="UTF-8"%>

Getting all parameter values in servlet

<b>Contact No:</b>

<b>Email:</b>

ParameterValues.java

package com.ebhor.parametervalues;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "ParameterValues", urlPatterns = {"/parametervalues"})
public class ParameterValues extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            out.println("");
            out.println("");
            out.println("");
            out.println("");
            out.println("");
            out.println("");
            Enumeration parameterNames = request.getParameterNames();
            out.println("Parameter name and values are");
            while (parameterNames.hasMoreElements()) {
                String parameterName = parameterNames.nextElement();
                out.println("  "+parameterName+" ");
                String[] values = request.getParameterValues(parameterName);
                for (String value : values) {
                    out.println( value+"  ");
                }
            }
            out.println("");
            out.println("");
        } finally {
            out.close();
        }
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }
}

package com.ebhor.parametervalues;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Enumeration;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "ParameterValues", urlPatterns = {"/parametervalues"})

public class ParameterValues extends HttpServlet {

protected void processRequest(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out = response.getWriter();

try {

out.println("");

Enumeration parameterNames = request.getParameterNames();

out.println("Parameter name and values are");

while (parameterNames.hasMoreElements()) {

String parameterName = parameterNames.nextElement();

out.println(" "+parameterName+" ");

String[] values = request.getParameterValues(parameterName);

for (String value : values) {

out.println( value+" ");

}

out.println("");

} finally {

out.close();

}

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

processRequest(request, response);

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

processRequest(request, response);

}

pom.xml

    4.0.0

    com.ebhor
    parameterValues
    1.0-SNAPSHOT
    war

    parameterValues

    
        ${project.build.directory}/endorsed
        UTF-8
    

    
        
            javax
            javaee-web-api
            6.0
            provided
        
    

    
        
            
                org.apache.maven.plugins
                maven-compiler-plugin
                2.3.2
                
                    1.6
                    1.6
                    
                        ${endorsed.dir}
                    
                
            
            
                org.apache.maven.plugins
                maven-war-plugin
                2.1.1
                
                    false
                
            
            
                org.apache.maven.plugins
                maven-dependency-plugin
                2.1
                
                    
                        validate
                        
                            copy
                        
                        
                            ${endorsed.dir}
                            true
                            
                                
                                    javax
                                    javaee-endorsed-api
                                    6.0
                                    jar

4.0.0

com.ebhor

parameterValues

1.0-SNAPSHOT

war

parameterValues

${project.build.directory}/endorsed

UTF-8

javax

javaee-web-api

6.0

provided

org.apache.maven.plugins

maven-compiler-plugin

2.3.2

1.6

${endorsed.dir}

org.apache.maven.plugins

maven-war-plugin

2.1.1

false

org.apache.maven.plugins

maven-dependency-plugin

2.1

validate

copy

${endorsed.dir}

true

javax

javaee-endorsed-api

6.0

jar

Result

Servlet url and class mapping using web.xml

May 2, 2023May 2, 2023 by manish

We can map url pattern with servlet class at web.xml. Following example will illustrate this. Project directory structure is as below: index.jsp

&lt;%@page contentType="text/html" pageEncoding="UTF-8"%&gt;


    
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    
    


<h1>Configuration using web.xml</h1>


        <a href="welcome1">Show Welcome1</a>

<%@page contentType="text/html" pageEncoding="UTF-8"%>

<h1>Configuration using web.xml</h1>

<a href="welcome1">Show Welcome1</a>

web.xml

<!--?xml version="1.0" encoding="UTF-8"?-->

<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
   

    <display-name>Servlet Tutorial 1</display-name>
    <description>
        This is a simple web application. To map url with srvlet class at web.xml
    </description>

    <servlet>
        <servlet-name>welcome</servlet-name>
        <servlet-class>ebhor.servlet.Welcome1</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>welcome</servlet-name>
        <url-pattern>/welcome1</url-pattern>
    </servlet-mapping>

</web-app>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

<display-name>Servlet Tutorial 1</display-name>

This is a simple web application. To map url with srvlet class at web.xml

</description>

<servlet-name>welcome</servlet-name>

<servlet-class>ebhor.servlet.Welcome1</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>welcome</servlet-name>

<url-pattern>/welcome1</url-pattern>

</servlet-mapping>

</web-app>

Welcome1.java

package ebhor.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Welcome1 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            out.println("");
            out.println("");
            out.println("");
            out.println("<title>Servlet Welcome1</title>");
            out.println("");
            out.println("");
            out.println("

<h1>Servlet Welcome1</h1>

");
            out.println("");
            out.println("");
        } finally {
            out.close();
        }
    }
}

package ebhor.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class Welcome1 extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out = response.getWriter();

try {

out.println("");

out.println("<title>Servlet Welcome1</title>");

out.println("");

out.println("

<h1>Servlet Welcome1</h1>

");

out.println("");

} finally {

out.close();

}

In web.xml url pattern(welcome1) will match to a logical name(welcome) that logical name is matched with servlet fully qualified class name(ebhor.servlet.Welcome1). Result: