The best Data Access Object Pattern Tutorial In 2024, In this tutorial you can learn achieve,step 1,Step 2,Step 3,Step 4,Step 5,

Data Access Object Pattern

Data Access Object Model (Data Access Object Pattern) or DAO pattern for the low-level data access API or separated from the operation of advanced business services. The following is a participant in the Data Access Object pattern.

• Interface Data Access Objects (Data Access Object Interface) - This interface defines the standard operations on a model object to be executed.
• Data Access Objects entity classes (Data Access Object concrete class) - This class implements the above interfaces.This class is responsible for getting data from the data source, the data source can be a database, it can be xml, or other storage mechanism.
• Model Object / value objects (Model Object / Value Object) - The object is simple POJO, includes get / set methods to store by using DAO classes to retrieve data.

achieve

We will create aStudentobject model object or value object as.StudentDaodata access object interface.StudentDaoImplentity class is to achieve a data access object interface.DaoPatternDemo,our demonstration class to demonstrate the use ofStudentDaoData Access Object pattern of usage.

step 1

Create a value object.

Student.java

public class Student {
   private String name;
   private int rollNo;

   Student (String name, int rollNo) {
      this.name = name;
      this.rollNo = rollNo;
   }

   public String getName () {
      return name;
   }

   public void setName (String name) {
      this.name = name;
   }

   public int getRollNo () {
      return rollNo;
   }

   public void setRollNo (int rollNo) {
      this.rollNo = rollNo;
   }
}

Step 2

Create a data access object interface.

StudentDao.java

import java.util.List;

public interface StudentDao {
   public List <Student> getAllStudents ();
   public Student getStudent (int rollNo);
   public void updateStudent (Student student);
   public void deleteStudent (Student student);
}

Step 3

Create entity class implements the above interfaces.

StudentDaoImpl.java

import java.util.ArrayList;
import java.util.List;

public class StudentDaoImpl implements StudentDao {
	
   // List is a database as a List <Student> students;

   public StudentDaoImpl () {
      students = new ArrayList <Student> ();
      Student student1 = new Student ( "Robert", 0);
      Student student2 = new Student ( "John", 1);
      students.add (student1);
      students.add (student2);		
   }
   @Override
   public void deleteStudent (Student student) {
      students.remove (student.getRollNo ());
      System.out.println ( "Student: Roll No" + student.getRollNo () 
         + ", Deleted from database");
   }

   // Retrieve the list of students from the database @Override
   public List <Student> getAllStudents () {
      return students;
   }

   @Override
   public Student getStudent (int rollNo) {
      return students.get (rollNo);
   }

   @Override
   public void updateStudent (Student student) {
      students.get (student.getRollNo ()) setName (student.getName ()).;
      System.out.println ( "Student: Roll No" + student.getRollNo () 
         + ", Updated in the database");
   }
}

Step 4

StudentDaoto demonstrate the use of the Data Access Object pattern of usage.

CompositeEntityPatternDemo.java

public class DaoPatternDemo {
   public static void main (String [] args) {
      StudentDao studentDao = new StudentDaoImpl ();

      // Output all students for (Student student: studentDao.getAllStudents ()) {
         System.out.println ( "Student: [RollNo:"
            + Student.getRollNo () + ", Name:" + student.getName () + "]");
      }


      // Update Student Student student = studentDao.getAllStudents () get (0).;
      student.setName ( "Michael");
      studentDao.updateStudent (student);

      // Get students studentDao.getStudent (0);
      System.out.println ( "Student: [RollNo:"
         + Student.getRollNo () + ", Name:" + student.getName () + "]");		
   }
}

Step 5

Verify output.

Student: [RollNo: 0, Name: Robert]
Student: [RollNo: 1, Name: John]
Student: Roll No 0, updated in the database
Student: [RollNo: 0, Name: Michael]