JSP Setup Tomcat First JSP Page

Prerequisites and Project Layout

A JSP page runs inside a Servlet container; the browser never executes JSP source. The container translates the page into a Servlet, compiles it, runs it for a request, and sends only the generated response body to the client.

Use a supported JDK and a Jakarta Servlet container such as Tomcat. JSP applications need a web root for public resources and a WEB-INF directory for protected configuration, classes, and libraries. Files below WEB-INF cannot be requested directly, which makes it the correct location for views that must be reached through a controller.

Match the API namespace to the container generation. Current Jakarta containers use jakarta.servlet packages; older Java EE containers use javax.servlet. Mixing those APIs produces deployment or class-loading failures even when the Java code compiles in the editor.

Keep Java source under src/main/java and JSP views under src/main/webapp.
Place controller-only JSP files under WEB-INF/views.
Do not put database passwords or Java source in the public web root.

First JSP Request

A minimal JSP can contain ordinary HTML plus Expression Language. Deploy the application to the container and request it through the application context, for example http://localhost:8080/shop/hello.jsp. Opening the file from disk bypasses the container and cannot execute JSP.

On the first request, the container may translate and compile the page, so it can be slower than later requests. A translation or compilation error appears in container logs with the generated Servlet location and the original JSP line where possible.

Confirm the container port and application context path.
Use the HTTP URL, not a file:// path.
Read deployment logs before changing JSP markup after a 404.

Controller-to-View Flow

Production JSP is normally a view, not the request controller. A Servlet validates input, calls application services, stores view data as request attributes, and forwards to a JSP. The JSP renders those values with EL and tags. This separation keeps SQL, authorization, redirects, and business rules out of the template.

Forward when the same request should render a view and retain request attributes. Redirect when the browser must make a new request, commonly after a successful POST. A redirect loses request attributes unless data is stored elsewhere, and it changes the browser URL.

Deployment Diagnosis

A 404 means the context path or resource mapping was not found; it is different from a JSP compilation failure, which normally returns a 500. Confirm that the application deployed, inspect the expanded artifact or WAR, check filename case, and verify whether the page is intentionally under WEB-INF.

After edits, make sure the container detects the changed file. For repeatable builds, package the application through the project build rather than copying random class files into the running server. Keep container, JDK, and Jakarta API versions recorded with the project.

Minimal JSP View

<%@ page contentType="text/html;charset=UTF-8" %>
      <!doctype html>
      <html lang="en">
      <head><meta charset="UTF-8"><title>Hello JSP</title></head>
      <body>
        <h1>Hello, ${empty requestScope.name ? 'visitor' : requestScope.name}</h1>
      </body>
      </html>

The container evaluates EL before returning HTML.
The browser receives no JSP directive or EL source.

Servlet Forward to a Protected JSP

@WebServlet("/hello")
      public class HelloServlet extends HttpServlet {
          @Override
          protected void doGet(HttpServletRequest request,
                               HttpServletResponse response)
                  throws ServletException, IOException {
              request.setAttribute("name", "Asha");
              request.getRequestDispatcher("/WEB-INF/views/hello.jsp")
                     .forward(request, response);
          }
      }

Before you move on