java 编写学生信息成绩管理系统的代码

好，下面提供一个简单的学生信息成绩管理系统的Java代码示例，包括学生信息、课程信息和成绩信息的增删改查操作。

1. 创建数据库表
首先需要在MySQL中创建三张表：student、course和score，用于存储学生信息、课程信息和成绩信息等。

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) NOT NULL,
  `gender` varchar(4) NOT NULL,
  `age` int(11) NOT NULL,
  `clazz` varchar(20) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `course` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) NOT NULL,
  `number` varchar(20) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `score` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `student_id` int(11) NOT NULL,
  `course_id` int(11) NOT NULL,
  `score` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

2. 创建JavaBean
创建JavaBean来存储学生、课程和成绩等信息，如下：

public class Student {
    private int id;
    private String name;
    private String gender;
    private int age;
    private String clazz;
    // getter和setter方法省略
}

public class Course {
    private int id;
    private String name;
    private String number;
    // getter和setter方法省略
}

public class Score {
    private int id;
    private int studentId;
    private int courseId;
    private int score;
    // getter和setter方法省略
}

3. 创建数据库操作类
创建一个数据库操作类，用于实现对数据库的增删改查操作，如下：

public class StudentDao {
    // 添加学生信息
    public void addStudent(Student student) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "INSERT INTO student(name, gender, age, clazz) VALUES(?,?,?,?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, student.getName());
            pstmt.setString(2, student.getGender());
            pstmt.setInt(3, student.getAge());
            pstmt.setString(4, student.getClazz());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 删除学生信息
    public void deleteStudent(int id) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "DELETE FROM student WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 修改学生信息
    public void updateStudent(Student student) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "UPDATE student SET name=?, gender=?, age=?, clazz=? WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, student.getName());
            pstmt.setString(2, student.getGender());
            pstmt.setInt(3, student.getAge());
            pstmt.setString(4, student.getClazz());
            pstmt.setInt(5, student.getId());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 查询学生信息
    public Student findStudent(int id) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        Student student = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM student WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                student = new Student();
                student.setId(rs.getInt("id"));
                student.setName(rs.getString("name"));
                student.setGender(rs.getString("gender"));
                student.setAge(rs.getInt("age"));
                student.setClazz(rs.getString("clazz"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
        return student;
    }
    // 查询所有学生信息
    public List<Student> findAllStudents() {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        List<Student> students = new ArrayList<Student>();
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM student";
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            while (rs.next()) {
                Student student = new Student();
                student.setId(rs.getInt("id"));
                student.setName(rs.getString("name"));
                student.setGender(rs.getString("gender"));
                student.setAge(rs.getInt("age"));
                student.setClazz(rs.getString("clazz"));
                students.add(student);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
        return students;
    }
}

public class CourseDao {
    // 添加课程信息
    public void addCourse(Course course) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "INSERT INTO course(name, number) VALUES(?,?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, course.getName());
            pstmt.setString(2, course.getNumber());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 删除课程信息
    public void deleteCourse(int id) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "DELETE FROM course WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 修改课程信息
    public void updateCourse(Course course) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "UPDATE course SET name=?, number=? WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, course.getName());
            pstmt.setString(2, course.getNumber());
            pstmt.setInt(3, course.getId());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 查询课程信息
    public Course findCourse(int id) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        Course course = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM course WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                course = new Course();
                course.setId(rs.getInt("id"));
                course.setName(rs.getString("name"));
                course.setNumber(rs.getString("number"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
        return course;
    }
    // 查询所有课程信息
    public List<Course> findAllCourses() {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        List<Course> courses = new ArrayList<Course>();
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM course";
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            while (rs.next()) {
                Course course = new Course();
                course.setId(rs.getInt("id"));
                course.setName(rs.getString("name"));
                course.setNumber(rs.getString("number"));
                courses.add(course);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
        return courses;
    }
}

public class ScoreDao {
    // 添加成绩信息
    public void addScore(Score score) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "INSERT INTO score(student_id, course_id, score) VALUES(?,?,?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, score.getStudentId());
            pstmt.setInt(2, score.getCourseId());
            pstmt.setInt(3, score.getScore());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 删除成绩信息
    public void deleteScore(int id) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "DELETE FROM score WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 修改成绩信息
    public void updateScore(Score score) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "UPDATE score SET student_id=?, course_id=?, score=? WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, score.getStudentId());
            pstmt.setInt(2, score.getCourseId());
            pstmt.setInt(3, score.getScore());
            pstmt.setInt(4, score.getId());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt);
        }
    }
    // 查询成绩信息
    public Score findScore(int id) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        Score score = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM score WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                score = new Score();
                score.setId(rs.getInt("id"));
                score.setStudentId(rs.getInt("student_id"));
                score.setCourseId(rs.getInt("course_id"));
                score.setScore(rs.getInt("score"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
        return score;
    }
    // 查询所有成绩信息
    public List<Score> findAllScores() {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        List<Score> scores = new ArrayList<Score>();
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM score";
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            while (rs.next()) {
                Score score = new Score();
                score.setId(rs.getInt("id"));
                score.setStudentId(rs.getInt("student_id"));
                score.setCourseId(rs.getInt("course_id"));
                score.setScore(rs.getInt("score"));
                scores.add(score);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
        return scores;
    }
}

4. 创建Servlet
创建Servlet来处理前端页面的请求，可以使用JSP或者Thymeleaf等模板引擎来实现动态页面，如下：

public class StudentServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理GET请求的代码
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理POST请求的代码
    }
}

public class CourseServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理GET请求的代码
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理POST请求的代码
    }
}

public class ScoreServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理GET请求的代码
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理POST请求的代码
    }
}

5. 创建数据库连接池
创建一个数据库连接池类，用于