Create a web servlet (the servlet is located on the web server, returns the result on request)

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Create a web servlet (the servlet is located on the web server, returns the result on request) | Java

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Create a web servlet (the servlet is located on the web server, returns the result on request) | Java

last updated: 10 April 2025

Here's my servlet

File MainServlet.java

@WebServlet("/hello")
public class MainServlet extends HttpServlet {

     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
     {
          resp.setContentType("text/html");
          PrintWriter printWriter = resp.getWriter();
          printWriter.write("Good morning!");
          printWriter.close();
     }
}

Explanation!
On the path /hello my servlet MainServlet will be executed.
The name MainServlet can be invented by any name and it does not affect anything.
Important is the path @WebServlet("/hello")
And it is important what the servlet returns. My servlet will return the value of "Good morning!" as "text/html"

That is, to make a servlet out of a regular class, it must be inherited from the class HttpServlet.
Above the class, specify the annotation @WebServlet(), in which we bind the servlet to a specific path /hello.

Start the project and open the link:
http://localhost:8080/MyServlet1/hello
We see that our servlet is working on the path /hello, i.e. it gives an answer Good morning!

Download an example:

MyServlet1.zip ...
size: 120 kb

Note! You must have Java JDK installed. If you don't have it, then need to download and install Java JDK ...

Note! You must have IntelliJ IDEA Ultimate installed. If you don't have it, then need to download and install IntelliJ IDEA Ultimate ...

Note! You must have Tomcat Web Server installed. If you don't have it, then need to download and install Tomcat Web Server ...

Step 1. Creating a new project

Select the project: Maven Archtype
Choose the type: webapp

The project was created:
jsp A file is a web page.

Let's try to run the project:

Click on the green triangle

The Edit configuration window with the default configuration appeared.
At the bottom, we see an error Error: Module is not selected

Step 2. To launch this web project well, you need to add a web server (add the Smart Tomcat plugin, this is a lightweight web server)

Click on Edit Configurations

Click on +
click on Smart Tomcat
Note! If there is no Smart Tomcat in the list, then You need to install Smart Tomcat plugin in Intellij Idea ...

A window appeared with the configuration for Smart Tomcat
I don't change anything, click on OK

Step 3. Launching the project

Click on the green triangle

The application starts and sees the command in Console:

C:\Users\echig\.jdks\openjdk-22.0.1\bin\java.exe "-Dcatalina.home=C:\Program Files\Apache Software Foundation\Tomcat 9.0"
-Dcatalina.base=C:\Users\echig\.SmartTomcat\MyServlet1\MyServlet1
-Djava.io.tmpdir=C:\Users\echig\.SmartTomcat\MyServlet1\MyServlet1\temp
-Djava.util.logging.config.file=C:\Users\echig\.SmartTomcat\MyServlet1\MyServlet1\conf\logging.properties
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2024.3\lib\idea_rt.jar=59545:C:\Program Files\JetBrains\IntelliJ IDEA 2024.3\bin"
-Dfile.encoding=UTF-8
-Dsun.stdout.encoding=UTF-8
-Dsun.stderr.encoding=UTF-8
-classpath "C:\Program Files\Apache Software Foundation\Tomcat 9.0\bin\bootstrap.jar;C:\Program Files\Apache Software Foundation\Tomcat 9.0\bin\tomcat-juli.jar"
org.apache.catalina.startup.Bootstrap start

This means that the web server will be terminated Tomcat

Click on the link:
http://localhost:8080/MyServlet1

We see that our web page has been launched on a web server:

Attention!
If we run a project and an error:
Error running 'Unnamed'
java.io.FileNotFoundException:
C:\Users\echig\.SmartTomcat\MyServlet1\ MyServiet1conf\server.xml (The system cannot find the file specified)
Decision:
You need to recreate the project from the beginning.

Step 4. Add the javax.servlet-api library to the pom.xml file

In the pom.xml file, connect the libraries.

Xml File pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.example</groupId>
     <artifactId>MyServlet1</artifactId>
     <packaging>war</packaging>
     <version>1.0-SNAPSHOT</version>
     <name>MyServlet1 Maven Webapp</name>
     <url>http://maven.apache.org</url>
     <dependencies>
          <dependency>
               <groupId>junit</groupId>
               <artifactId>junit</artifactId>
               <version>3.8.1</version>
               <scope>test</scope>
          </dependency>
          <dependency>
               <groupId>javax.servlet</groupId>
               <artifactId>javax.servlet-api</artifactId>
               <version>4.0.1</version>
          </dependency>
     </dependencies>
     <build>
          <finalName>MyServlet1</finalName>
     </build>
</project>

Attention!
After adding <dependency> ... </dependency> to the pom.xml file, this library will not be downloaded from the Internet.
To download this library from the Internet, you need to close the project and click open project

Step 5. Create a Java folder and make a servlet file MainServlet.java

Let's create a folder Java

Inside the Java folder, create a new file MainServlet.java:

Java File MainServlet.java

@WebServlet("/hello")
public class MainServlet extends HttpServlet {

     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
     {
          resp.setContentType("text/html");
          PrintWriter printWriter = resp.getWriter();
          printWriter.write("Good morning!");
          printWriter.close();
     }
}

Step 6. Launch the project and see how the servlet works

Click on the link:
http://localhost:8080/MyServlet1

add at the end /hello
Just like that
http://localhost:8080/MyServlet1/hello
We see that our servlet is running on a web server: