JSP Refactor (#3689)

javax-servlets/src/main/java/com/baeldung/controller/StudentServlet.java

@@ -1,6 +1,6 @@
 package com.baeldung.controller;
 
-import java.io.IOException;
+import com.baeldung.service.StudentService;
 
 import javax.servlet.RequestDispatcher;
 import javax.servlet.ServletException;
@@ -8,23 +8,19 @@ import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
 
-import com.baeldung.service.StudentService;
-
-/**
- * 
- * @author haseeb
- *
- */
 @WebServlet(name = "StudentServlet", urlPatterns = "/student-record")
 public class StudentServlet extends HttpServlet {
 
-    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
-        StudentService studentService = new StudentService();
+    private final StudentService studentService = new StudentService();
+
+    private void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         String studentID = request.getParameter("id");
         if (studentID != null) {
             int id = Integer.parseInt(studentID);
-            request.setAttribute("studentRecord", studentService.getStudent(id));
+            studentService.getStudent(id)
+              .ifPresent(s -> request.setAttribute("studentRecord", s));
         }
 
         RequestDispatcher dispatcher = request.getRequestDispatcher("/WEB-INF/jsp/student-record.jsp");

javax-servlets/src/main/java/com/baeldung/model/Student.java

@@ -1,10 +1,5 @@
 package com.baeldung.model;
 
-/**
- * 
- * @author haseeb
- *
- */
 public class Student {
 
     private int id;
@@ -18,44 +13,26 @@ public class Student {
         this.lastName = lastName;
     }
 
-    /**
-     * @return the id
-     */
     public int getId() {
         return id;
     }
 
-    /**
-     * @param id the id to set
-     */
     public void setId(int id) {
         this.id = id;
     }
 
-    /**
-     * @return the firstName
-     */
     public String getFirstName() {
         return firstName;
     }
 
-    /**
-     * @param firstName the firstName to set
-     */
     public void setFirstName(String firstName) {
         this.firstName = firstName;
     }
 
-    /**
-     * @return the lastName
-     */
     public String getLastName() {
         return lastName;
     }
 
-    /**
-     * @param lastName the lastName to set
-     */
     public void setLastName(String lastName) {
         this.lastName = lastName;
     }

javax-servlets/src/main/java/com/baeldung/service/StudentService.java

@@ -2,33 +2,20 @@ package com.baeldung.service;
 
 import com.baeldung.model.Student;
 
-/**
- * 
- * @author haseeb
- *
- */
+import java.util.Optional;
+
 public class StudentService {
 
-    /**
-     * 
-     * @param id
-     * @return
-     */
-    public Student getStudent(int id) {
-
-        Student student = null;
-
+    public Optional<Student> getStudent(int id) {
         switch (id) {
-        case 1:
-            student = new Student(1, "John", "Doe");
-            break;
-        case 2:
-            student = new Student(2, "Jane", "Goodall");
-            break;
-        case 3:
-            student = new Student(3, "Max", "Born");
-            break;
+            case 1:
+                return Optional.of(new Student(1, "John", "Doe"));
+            case 2:
+                return Optional.of(new Student(2, "Jane", "Goodall"));
+            case 3:
+                return Optional.of(new Student(3, "Max", "Born"));
+            default:
+                return Optional.empty();
         }
-        return student;
     }
 }

javax-servlets/src/main/java/com/baeldung/servlets/FormServlet.java

@@ -1,7 +1,6 @@
 package com.baeldung.servlets;
 
 import javax.servlet.RequestDispatcher;
-import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
@@ -13,7 +12,7 @@ public class FormServlet extends HttpServlet {
 
     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
-            throws ServletException, IOException {
+      throws IOException {
 
         String height = request.getParameter("height");
         String weight = request.getParameter("weight");
@@ -28,20 +27,17 @@ public class FormServlet extends HttpServlet {
             RequestDispatcher dispatcher = request.getRequestDispatcher("/WEB-INF/jsp/index.jsp");
             dispatcher.forward(request, response);
         } catch (Exception e) {
-
             response.sendRedirect("index.jsp");
         }
     }
 
     @Override
-    protected void doGet(HttpServletRequest request, HttpServletResponse response)
-            throws ServletException, IOException {
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) {
 
         // do something else here
     }
 
     private Double calculateBMI(Double weight, Double height) {
-
         return weight / (height * height);
     }
 }