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Вывод изображения (Java Servlet + MySQL)
#39785658
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Я написала программу которая добавляет фио студента с его изображением которая хранится в web/images. Как можно сделать так, чтобы он брал изображения с локального диска компьютера и давал каждому новому изображению id.
Вот мой код
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package servlet;
import dao.DatabaseDAO;
import entity.Student;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import static java.lang.Integer.parseInt;
import java.util.List;
public class MyServlet extends HttpServlet {
private DatabaseDAO dao;
@Override
public void init() throws ServletException {
dao = new DatabaseDAO();
}
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String action = request.getParameter("actionname");
if (action.equals("RemoveStudent")) {
int id = parseInt(request.getParameter("id"));
boolean deleted = dao.deleteStudentFromDB(id);
String message;
if (deleted) {
message = "Студент удален.";
} else {
message = "Студент не существует";
}
request.setAttribute("message", message);
List<Student> students = dao.readAllStudentsFromDB();
request.setAttribute("students", students);
request.getRequestDispatcher("ShowAllStudent.jsp").forward(request, response);
}
if (action.equals("ShowAllStudent")) {
List<Student> students = dao.readAllStudentsFromDB();
request.setAttribute("students", students);
request.getRequestDispatcher("ShowAllStudent.jsp").forward(request, response);
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
Add Student Servlet
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package servlet;
import dao.DatabaseDAO;
import entity.Student;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import static java.lang.Integer.parseInt;
import java.util.List;
public class MyServlet extends HttpServlet {
private DatabaseDAO dao;
@Override
public void init() throws ServletException {
dao = new DatabaseDAO();
}
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String action = request.getParameter("actionname");
if (action.equals("RemoveStudent")) {
int id = parseInt(request.getParameter("id"));
boolean deleted = dao.deleteStudentFromDB(id);
String message;
if (deleted) {
message = "Студент удален.";
} else {
message = "Студент не существует";
}
request.setAttribute("message", message);
List<Student> students = dao.readAllStudentsFromDB();
request.setAttribute("students", students);
request.getRequestDispatcher("ShowAllStudent.jsp").forward(request, response);
}
if (action.equals("ShowAllStudent")) {
List<Student> students = dao.readAllStudentsFromDB();
request.setAttribute("students", students);
request.getRequestDispatcher("ShowAllStudent.jsp").forward(request, response);
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
DAO database
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package dao;
import entity.Student;
import java.sql.*;
import java.util.ArrayList;
public class DatabaseDAO {
private static final String URL = "jdbc:mysql://localhost:3306/school_db_newnew?useTimezone=true&serverTimezone=GMT";
private static final String USER = "root";
private static final String PASSWORD = "123456";
private static final String GET_ALL_STUDENTS_QUERY
= "SELECT * FROM student;";
private static final String INSERT_STUDENT_QUERY
= "INSERT INTO student (name, surname, image) VALUES(?,?,?);";
public static final String DELETE_STUDENT_QUERY = "DELETE FROM student WHERE id = ?;";
private Connection conn;
public DatabaseDAO() {
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(URL, USER, PASSWORD);
} catch (SQLException | ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
public ArrayList<Student> readAllStudentsFromDB() {
ArrayList<Student> result = new ArrayList<>();
try (PreparedStatement stmt = conn.prepareStatement(GET_ALL_STUDENTS_QUERY)) {
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
int id = rs.getInt("id");
String firstName = rs.getString("name");
String lastName = rs.getString("surname");
String image = rs.getString("image");
Student student = new Student(firstName, lastName);
student.setId(id);
student.setImage(image);
result.add(student);
}
} catch (SQLException e) {
throw new RuntimeException(e);
}
return result;
}
public void insertStudentIntoDB(String name, String surname, String filename) {
try (PreparedStatement stmt
= conn.prepareStatement(INSERT_STUDENT_QUERY, Statement.RETURN_GENERATED_KEYS)) {
stmt.setString(1, name);
stmt.setString(2, surname);
stmt.setString(3, filename);
stmt.executeUpdate();
ResultSet keys = stmt.getGeneratedKeys();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
public boolean deleteStudentFromDB(int id) {
try (PreparedStatement stmt = conn.prepareStatement(DELETE_STUDENT_QUERY)) {
stmt.setInt(1, id);
int rowsDeleted = stmt.executeUpdate();
return rowsDeleted > 0;
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
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