add: csrf token demo

spring_security/spring_security_exercise/src/main/java/com/thuta/spring_security_exercise/Controllers/StudentController.java

@@ -0,0 +1,37 @@
+package com.thuta.spring_security_exercise.Controllers;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.security.web.csrf.CsrfToken;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.thuta.spring_security_exercise.Entity.Student;
+
+import jakarta.servlet.http.HttpServletRequest;
+
+@RestController
+public class StudentController {
+    private List<Student> students = new ArrayList<>(List.of(
+            new Student(1, "Navin", 60),
+            new Student(2, "Kiran", 65)));
+
+    @GetMapping("/students")
+    public List<Student> getStudents() {
+        return this.students;
+    }
+
+    @GetMapping("/csrf-token")
+    public CsrfToken getCsrfToken(HttpServletRequest request) {
+        return (CsrfToken) request.getAttribute("_csrf");
+    }
+
+    @PostMapping("/students")
+    public Student addStudent(@RequestBody Student student) {
+        students.add(student);
+        return student;
+    }
+}

spring_security/spring_security_exercise/src/main/java/com/thuta/spring_security_exercise/Entity/Student.java

@@ -0,0 +1,37 @@
+package com.thuta.spring_security_exercise.Entity;
+
+public class Student {
+    private int id;
+    private String name;
+    private int marks;
+
+    public Student(int id, String name, int marks) {
+        this.id = id;
+        this.name = name;
+        this.marks = marks;
+    }
+
+    public int getId() {
+        return this.id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getMarks() {
+        return this.marks;
+    }
+
+    public void setMarks(int marks) {
+        this.marks = marks;
+    }
+}