@Entity
@Table (name = "post")
public class Post {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column (name = "id")
    private long id;

    @Column (name = "title", nullable = false)
    private String title;

    @Column (name = "summary", nullable = false)
    private String summary;

    @Column (name = "body", nullable = false)
    private String body;
    @ManyToOne (cascade = CascadeType.REFRESH)
    @JoinColumn(name = "category_id")
    private Category category;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getSummary() {
        return summary;
    }

    public void setSummary(String summary) {
        this.summary = summary;
    }

    public String getBody() {
        return body;
    }

    public void setBody(String body) {
        this.body = body;
    }

    public Category getCategory() {
        return category;
    }

    public void setCategory(Category category) {
        this.category = category;
    }

    public Post(String title, String summary, String body, Category category) {

        this.title = title;
        this.summary = summary;
        this.body = body;
        this.category = category;
    }

    public Post() {

    }
    public Post(ResultSet resultSet, Category category){
        try {
            this.id = resultSet.getInt("id");
            this.body = resultSet.getString("body");
            this.summary = resultSet.getString("summary");
            this.title = resultSet.getString("title");
            this.category = category;
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

@Entity
@Table(name = "category")
public class Category {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private long id;

    public String getCategoryName() {
        return categoryName;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }

    @Column(name = "category_name")
    private String categoryName;
    @OneToMany(mappedBy = "category")
    private List<Post> posts;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public List<Post> getPosts() {
        return posts;
    }

    public void setPosts(List<Post> posts) {
        this.posts = posts;
    }

    public Category() {

    }
}

public class QueryProperties {

    Properties queries;

    private final String URL = "jdbc:mysql://localhost:3306/postschema";
    private final String USERNAME = "root";
    private final String PASSWORD = "peroser12";

    public QueryProperties() {
       loadProperties();
    }

    public Connection getConnectionDB()
    {
        Connection connection = null;
        try {
            Driver driver = new FabricMySQLDriver();
            DriverManager.registerDriver(driver);
            connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);

        } catch (SQLException e) {
            System.err.println("Driver not found!");        }

    return connection;
    }

    public String getQuery (String name){
        System.out.println("Get query " + name);
        if (queries == null)
            loadProperties();
            String q = queries.getProperty(name);
            System.out.println(q);
            return q;

    }

    private void loadProperties(){
        FileInputStream fis;
        try {
            fis = new FileInputStream("src/main/resources/queries.properties");
            queries = new Properties();
            queries.load(fis);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public interface AbstractDao <T> {

    public T create(T entity);
    public void delete(T entity);
    public T edit(T entity);
    public T getById(Integer id);
    public List<T> getAll();

}

public abstract class AbstractDaoImpl<T> implements AbstractDao<T> {

        QueryProperties queryProperties = new QueryProperties();

    public T create(T entity) {
        Connection connection = null;
        PreparedStatement pstmt = null;
        ResultSet resultSet = null;
        try {
            connection = queryProperties.getConnectionDB();
            String querys = getCreateQuery();
            pstmt = connection.prepareStatement(querys, Statement.NO_GENERATED_KEYS);
            fillCreateStatement(pstmt, entity);
            pstmt.executeUpdate();

            resultSet = pstmt.getGeneratedKeys();
            if (resultSet.next()){
                Integer generatedId = resultSet.getInt(1);
                return getById(generatedId);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            if (resultSet != null)  try { resultSet.close(); } catch (SQLException logOrIgnore) {}
            if (pstmt != null)      try { pstmt.close(); } catch (SQLException logOrIgnore) {}
            if (connection != null) try { connection.close(); } catch (SQLException logOrIgnore) {}
        }


        return null;
    }
}


public class PostDao extends AbstractDaoImpl<Post> {

    @Override
    public void fillCreateStatement(PreparedStatement pstmt, Post entity) {
        try {
            pstmt.setString(1, entity.getBody());
            pstmt.setString(2, entity.getSummary());
            pstmt.setString(3, entity.getTitle());
            pstmt.setLong(4, entity.getCategory().getId());
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        PostDao postDao = new PostDao();
        Post post = new Post();
        Category category = new Category();
        category.setCategoryName("usdgliuidfl");
        post.setTitle("jgsdhjksddlgh");
        post.setSummary("skdjhgdgsd");
        post.setBody("jhgsdajkldgh");
        post.setCategory(category);
        postDao.create(post);
        System.out.println("Added!");
    }
}