作业管理系统实现

朴灿烈づ我的快乐病毒、 2023-10-05 17:33 55阅读 0赞

2.6系统实现  
2.6.1JavaEE 实现 —— MVC 模式  
DBCP.java——数据库连接池

实现代码如下：

package com.javaEE.code.class12;
    
    import org.apache.commons.dbcp.BasicDataSource;
    
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.SQLException;
    import java.util.Properties;
    
    // Database Connection Pool
    public class DBCP {
        
    
        // 数据库连接池
        private static BasicDataSource dbcp;
    
        //为不同线程管理连接
        private static ThreadLocal<Connection> tl;
    
        //通过配置文件来获取数据库参数
        static {
        
            try {
        
                Properties properties = new Properties();
    
                InputStream inputStream = DBCP.class.getClassLoader().getResourceAsStream("com/javaEE/code/class12/Application.properties");
    
                properties.load(inputStream);
                inputStream.close();
    
                // 初始化连接池
                dbcp = new BasicDataSource();
    
                // 数据库驱动 (Class.forName())
                dbcp.setDriverClassName(properties.getProperty("driverName"));
                // 数据库url
                dbcp.setUrl(properties.getProperty("dbUrl"));
                // 数据库用户名
                dbcp.setUsername(properties.getProperty("userName"));
                // 数据库密码
                dbcp.setPassword(properties.getProperty("password"));
                // 初始化连接数量
                dbcp.setInitialSize(Integer.parseInt(properties.getProperty("initSize")));
                // 连接池允许的最大连接数
                dbcp.setMaxActive(Integer.parseInt(properties.getProperty("maxActive")));
                // 最大等待时间
                dbcp.setMaxWait(Integer.parseInt(properties.getProperty("maxWait")));
                // 最小空闲数
                dbcp.setMinIdle(Integer.parseInt(properties.getProperty("minIdle"))            );
                // 最大空闲数
                dbcp.setMaxIdle(Integer.parseInt(properties.getProperty("maxIdle")));
                // 初始化线程本地
                tl = new ThreadLocal<Connection>();
            } catch (Exception e) {
        
                e.printStackTrace();
            }
        }
    
        // 通过连接池获取一个连接
        public static Connection getConnection() throws SQLException {
        
            Connection conn = dbcp.getConnection();
            tl.set(conn);
            return conn;
        }
    
        // 归还连接，未关闭
        public static void closeConnection() {
        
            try {
        
                Connection conn = tl.get();
                if (conn != null) {
        
                    conn.close();
                    tl.remove();
                }
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    }

2.6.2Model 层——实体类的实现  
Homework.java  
实现代码如下：

package com.javaEE.code.class12.model;
    
    import java.util.Date;
    
    public class Homework {
        
    
        private Long id;
    
        private String homeworkTittle;
    
        private String homeworkContent;
    
        private Date createTime;
    
        private Date updateTime;
    
        public Long getId() {
        
            return id;
        }
    
        public void setId(Long id) {
        
            this.id = id;
        }
    
        public String getHomeworkTittle() {
        
            return homeworkTittle;
        }
    
        public void setHomeworkTittle(String homeworkTittle) {
        
            this.homeworkTittle = homeworkTittle;
        }
    
        public String getHomeworkContent() {
        
            return homeworkContent;
        }
    
        public void setHomeworkContent(String homeworkContent) {
        
            this.homeworkContent = homeworkContent;
        }
    
        public Date getCreateTime() {
        
            return createTime;
        }
    
        public void setCreateTime(Date createTime) {
        
            this.createTime = createTime;
        }
    
        public Date getUpdateTime() {
        
            return updateTime;
        }
    
        public void setUpdateTime(Date updateTime) {
        
            this.updateTime = updateTime;
        }
    
        @Override
        public String toString() {
        
            return "Homework{" +
                    "id=" + id +
                    ", homeworkTittle='" + homeworkTittle + '\'' +
                    ", homeworkContent='" + homeworkContent + '\'' +
                    ", createTime=" + createTime +
                    ", updateTime=" + updateTime +
                    '}';
        }
    }
    
    Student.java
    package com.javaEE.code.class12.model;
    
    import java.util.Date;
    
    public class Student {
        
    
        private Long id;
    
        private String name;
    
        private Date createTime;
    
        private Date updateTime;
    
        public Long getId() {
        
            return id;
        }
    
        public void setId(Long id) {
        
            this.id = id;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public Date getCreateTime() {
        
            return createTime;
        }
    
        public void setCreateTime(Date createTime) {
        
            this.createTime = createTime;
        }
    
        public Date getUpdateTime() {
        
            return updateTime;
        }
    
        public void setUpdateTime(Date updateTime) {
        
            this.updateTime = updateTime;
        }
    
        @Override
        public String toString() {
        
            return "Student{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", createTime=" + createTime +
                    ", updateTime=" + updateTime +
                    '}';
        }
    }

StudentHomework.java

package com.javaEE.code.class12.model;
    
    import java.util.Date;
    
    public class StudentHomework {
        
    
        private Long id;
    
        private Long studentId;
    
        private Long homeworkId;
    
        private String homeworkTitle;
    
        private String homeworkContent;
    
        private Date createTime;
    
        private Date updateTime;
    
        public Long getId() {
        
            return id;
        }
    
        public void setId(Long id) {
        
            this.id = id;
        }
    
        public Long getStudentId() {
        
            return studentId;
        }
    
        public void setStudentId(Long studentId) {
        
            this.studentId = studentId;
        }
    
        public Long getHomeworkId() {
        
            return homeworkId;
        }
    
        public void setHomeworkId(Long homeworkId) {
        
            this.homeworkId = homeworkId;
        }
    
        public String getHomeworkTitle() {
        
            return homeworkTitle;
        }
    
        public void setHomeworkTitle(String homeworkTitle) {
        
            this.homeworkTitle = homeworkTitle;
        }
    
        public String getHomeworkContent() {
        
            return homeworkContent;
        }
    
        public void setHomeworkContent(String homeworkContent) {
        
            this.homeworkContent = homeworkContent;
        }
    
        public Date getCreateTime() {
        
            return createTime;
        }
    
        public void setCreateTime(Date createTime) {
        
            this.createTime = createTime;
        }
    
        public Date getUpdateTime() {
        
            return updateTime;
        }
    
        public void setUpdateTime(Date updateTime) {
        
            this.updateTime = updateTime;
        }
    
        @Override
        public String toString() {
        
            return "StudentHomework{" +
                    "id=" + id +
                    ", studentId=" + studentId +
                    ", homeworkId=" + homeworkId +
                    ", homeworkTitle='" + homeworkTitle + '\'' +
                    ", homeworkContent='" + homeworkContent + '\'' +
                    ", createTime=" + createTime +
                    ", updateTime=" + updateTime +
                    '}';
        }
    }

Controller 层 ——对数据的操作  
JDBC 类对数据进行直接操作  
Servlet 类接收 Http 请求，对数据库进行相应操作，并返回结果集给 Viewer 层  
StudentJDBC.java

package com.javaEE.code.class12.jdbc;
    
    import com.javaEE.code.class12.DBCP;
    import com.javaEE.code.class12.model.Student;
    
    import java.sql.*;
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    
    public class StudentJDBC {
        
    
        // 数据库连接
        private Connection connection = null;
        // 执行对象
        private PreparedStatement pstmt = null;
    
        // 查找所有记录
        public List<Student> selectAll() {
        
            // 定义 SQL 语句
            String sql = "SELECT * FROM s_student";
            System.out.println(sql);
            // 一条结果
            Student s = null;
            // 存储结果集
            List<Student> resultList = new ArrayList<>();
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                ResultSet resultSet = pstmt.executeQuery(sql);
                // 输出结果集
                while (resultSet.next()) {
        
                    // 初始化一条结果
                    s = new Student();
                    s.setId(resultSet.getLong("id"));
                    s.setName(resultSet.getString("name"));
                    s.setCreateTime(resultSet.getTimestamp("create_time"));
                    s.setUpdateTime(resultSet.getTimestamp("update_time"));
                    resultList.add(s);
                }
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
            return resultList;
        }
    
        // 添加一条记录
        public void addStudent(Student s) {
        
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "INSERT INTO s_student(id, name) VALUES (?, ?)";
            // 执行 SQL
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setLong(1, s.getId());
                pstmt.setString(2, s.getName());
                System.out.println(sql);
                pstmt.execute();
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
        // 删除一条记录
        public void deleteStudent(Student s) {
        
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "DELETE FROM s_student WHERE id=?";
            // 执行 SQL
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setLong(1, s.getId());
                System.out.println(sql);
                pstmt.execute();
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
        // 更新一条记录
        public void updateStudent(Student s) {
        
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "UPDATE s_student SET name=?, update_time=? WHERE id=?";
            //
            try {
        
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setString(1, s.getName());
                pstmt.setTimestamp(2, new Timestamp(new Date().getTime()));
                pstmt.setLong(3, s.getId());
                System.out.println(sql);
                pstmt.execute();
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
    //    public static void main(String[] args) {
        
    //        StudentJDBC sJDBC = new StudentJDBC();
    //        Student s = new Student();
    
        // To test addStudent(Student s)
    //        s.setId(100L);
    //        s.setName("ddd");
    //        sJDBC.addStudent(s);
    
        // To test selectAll()
    //        List<Student> list =  sJDBC.selectAll();
    //        for(Student student : list)
    //            System.out.println(student.getName());
    
        // To test deleteStudent(Student s)
    //        s.setId(100L);
    //        s.setName("ddd");
    //        sJDBC.deleteStudent(s);
    
        // To test updateStudent(Student s)
    //        s.setId(100L);
    //        s.setName("dd");
    //        sJDBC.updateStudent(s);
    
    //        sJDBC.closeAll();
    //    }
    }

HomeworkJDBC.java

package com.javaEE.code.class12.jdbc;
    
    import com.javaEE.code.class12.DBCP;
    import com.javaEE.code.class12.model.Homework;
    
    import java.sql.*;
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    
    public class HomeworkJDBC {
        
    
        // 数据库连接
        private Connection connection = null;
        // 执行对象
        private PreparedStatement pstmt = null;
    
        // 查找所有记录
        public List<Homework> selectAll() {
        
            // 定义 SQL 语句
            String sql = "SELECT * FROM s_homework";
            System.out.println(sql);
            // 一条结果
            Homework h = null;
            // 存储结果集
            List<Homework> resultList = new ArrayList<>();
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                ResultSet resultSet = pstmt.executeQuery(sql);
                // 输出结果集
                while (resultSet.next()) {
        
                    // 初始化一条结果
                    h = new Homework();
                    h.setId(resultSet.getLong("id"));
                    h.setHomeworkTittle(resultSet.getString("title"));
                    h.setHomeworkContent(resultSet.getString("content"));
                    h.setCreateTime(resultSet.getTimestamp("create_time"));
                    h.setUpdateTime(resultSet.getTimestamp("update_time"));
                    resultList.add(h);
                }
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
            return resultList;
        }
    
        // 添加一条记录
        public void addHomework(Homework h) {
        
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "INSERT INTO s_homework(title, content) VALUES (?, ?)";
            // 执行 SQL
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setString(1, h.getHomeworkTittle());
                pstmt.setString(2, h.getHomeworkContent());
                System.out.println(sql);
                pstmt.execute();
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
        // 删除一条记录
        public void deleteHomework(Homework h) {
        
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "DELETE FROM s_homework WHERE id=?";
            // 执行 SQL
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setLong(1, h.getId());
                System.out.println(sql);
                pstmt.execute();
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
        // 更新一条记录
        public void updateHomework(Homework h) {
        
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "UPDATE s_homework SET title=?, content=?, update_time=? WHERE id=?";
            //
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                PreparedStatement pstmt = connection.prepareStatement(sql);
                pstmt.setString(1, h.getHomeworkTittle());
                pstmt.setString(2, h.getHomeworkContent());
                pstmt.setTimestamp(3, new Timestamp(new Date().getTime()));
                pstmt.setLong(4, h.getId());
                System.out.println(sql);
                pstmt.execute();
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
    //    public static void main(String[] args) {
        
    //        HomeworkJDBC hJDBC = new HomeworkJDBC();
    //        Homework h = new Homework();
    
        // To test addHomework(Homework h)
    //        h.setId(100L);
    //        h.setHomeworkTittle("作业");
    //        h.setHomeworkContent("www.github.com");
    //        hJDBC.addHomework(h);
    
        // To test selectAll()
    //        List<Homework> list = hJDBC.selectAll();
    //        for (Homework homework : list)
    //            System.out.println(homework.getHomeworkContent());
    
        // To test updateHomework(Homework h)
    //        h.setId(100L);
    //        h.setHomeworkTittle("测试作业");
    //        h.setHomeworkContent("bjtu.edu.cn");
    //        hJDBC.updateHomework(h);
    
        // To test deleteHomework(Homework h)
    //        h.setId(100L);
    //        hJDBC.deleteHomework(h);
    //
    //        hJDBC.closeAll();
    //    }
    }

StudentHomeworkJDBC.java

package com.javaEE.code.class12.jdbc;
    
    import com.javaEE.code.class12.DBCP;
    import com.javaEE.code.class12.model.StudentHomework;
    
    import java.sql.*;
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    
    public class StudentHomeworkJDBC {
        
    
        // 数据库连接
        private Connection connection = null;
        // 执行对象
        private PreparedStatement pstmt = null;
    
        // 查找所有记录
        public List<StudentHomework> selectAll() {
        
    
            // 定义 SQL 语句
            String sql = "SELECT * FROM s_student_homework";
            System.out.println(sql);
            // 一条结果
            StudentHomework sh = null;
            // 存储结果集
            List<StudentHomework> resultList = new ArrayList<>();
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                // 获取结果集
                ResultSet resultSet = pstmt.executeQuery(sql);
                // 输出结果集
                while (resultSet.next()) {
        
                    // 初始化一条结果
                    sh = new StudentHomework();
                    sh.setId(resultSet.getLong("id"));
                    sh.setStudentId(resultSet.getLong("student_id"));
                    sh.setHomeworkId(resultSet.getLong("homework_id"));
                    sh.setHomeworkTitle(resultSet.getString("homework_title"));
                    sh.setHomeworkContent(resultSet.getString("homework_content"));
                    sh.setCreateTime(resultSet.getTimestamp("create_time"));
                    sh.setUpdateTime(resultSet.getTimestamp("update_time"));
                    resultList.add(sh);
                }
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
            return resultList;
        }
    
        // 添加一条记录
        public void addStudentHomework(StudentHomework sh) {
        
    
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "INSERT INTO s_student_homework(student_id, homework_id, homework_title, homework_content) VALUES (?, ?, ?, ?)";
            // 执行 SQL
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setLong(1, sh.getStudentId());
                pstmt.setLong(2, sh.getHomeworkId());
                pstmt.setString(3, sh.getHomeworkTitle());
                pstmt.setString(4, sh.getHomeworkContent());
                System.out.println(sql);
                pstmt.execute();
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
        // 删除一条记录
        public void deleteStudentHomework(StudentHomework sh) {
        
    
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "DELETE FROM s_student_homework WHERE id=?";
            // 执行 SQL
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                pstmt = connection.prepareStatement(sql);
                pstmt.setLong(1, sh.getId());
                System.out.println(sql);
                pstmt.execute();
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
        // 更新一条记录
        public void updateStudentHomework(StudentHomework sh) {
        
    
            // 定义 SQL 语句
            // PreparedStatement
            String sql = "UPDATE s_student_homework SET student_id=?, homework_id=?, homework_title=?, homework_content=?, update_time=? WHERE id=?";
            //
            try {
        
                // 获取连接
                connection = DBCP.getConnection();
                PreparedStatement pstmt = connection.prepareStatement(sql);
                pstmt.setLong(1, sh.getStudentId());
                pstmt.setLong(2, sh.getHomeworkId());
                pstmt.setString(3, sh.getHomeworkTitle());
                pstmt.setString(4, sh.getHomeworkContent());
                pstmt.setTimestamp(5, new Timestamp(new Date().getTime()));
                pstmt.setLong(6, sh.getId());
                System.out.println(sql);
                pstmt.execute();
                // 归还连接
                DBCP.closeConnection();
            } catch (SQLException e) {
        
                e.printStackTrace();
            }
        }
    
    //    public static void main(String[] args) {
        
    //        StudentHomeworkJDBC shJDBC = new StudentHomeworkJDBC();
    //        StudentHomework sh = new StudentHomework();
    
    //         To test selectAll()
    //        List<StudentHomework> list = shJDBC.selectAll();
    //        for (StudentHomework sh : list)
    //            System.out.println(sh.getHomeworkContent());
    
    //         To test addStudentHomework(StudentHomework sh)
    //        sh.setStudentId(104L);
    //        sh.setHomeworkId(104L);
    //        sh.setHomeworkTitle("作业");
    //        sh.setHomeworkContent("www.google.com");
    //        shJDBC.addStudentHomework(sh);
    
    //         To test deleteStudentHomework(StudentHomework sh)
    //        sh.setId(4L);
    //        shJDBC.deleteStudentHomework(sh);
    
    //         To test updateStudentHomework(StudentHomework sh)
    //        sh.setId(11L);
    //        sh.setHomeworkId(105L);
    //        sh.setStudentId(105L);
    //        sh.setHomeworkTitle("作业");
    //        sh.setHomeworkContent("bjtu.edu.cn");
    //        shJDBC.updateStudentHomework(sh);
    
    //          shJDBC.closeAll();
    //    }
    }

HomeworkStudentServlet.java 学生看到的作业列表，仅可提交作业

StudentServlet.java 学生列表

package com.javaEE.code.class12.servlet;
    
    import com.javaEE.code.class12.jdbc.StudentJDBC;
    import com.javaEE.code.class12.model.Student;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    import java.util.List;
    
    // 教师看到学生列表
    @WebServlet(name = "StudentServlet", urlPatterns = "/Student")
    public class 锕 extends HttpServlet {
        
        private StudentJDBC studentJDBC= new StudentJDBC();
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            List<Student> studentList = studentJDBC.selectAll();
            req.setAttribute("studentList", studentList);
    
            req.getRequestDispatcher("/jsp/teacher.jsp").forward(req, resp);
        }
    
        // https://www.cnblogs.com/xiaochuan94/p/9184444.html
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            req.setCharacterEncoding("utf-8");
            // 获取方法名
            String name = req.getParameter("method");
    
            if(name == null || name.isEmpty()){
        
                throw new RuntimeException("method parameter does not exist");
            }
    
            // 获得当前类的Class对象
            Class c = this.getClass();
            Method method = null;
            try {
        
                // 使用反射机制获取在本类中声明了的方法
                method =  getClass().getDeclaredMethod(name, HttpServletRequest.class, HttpServletResponse.class);
                // 反射调用方法
                method.invoke(this, req, resp);
            } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
        
                e.printStackTrace();
            }
        }
    
        protected void addStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{
        
            Student s = new Student();
            s.setId(Long.parseLong(req.getParameter("studentId")));
            s.setName(req.getParameter("studentName"));
            studentJDBC.addStudent(s);
            // 刷新页面
            resp.sendRedirect("Student");
        }
    
        protected void updateStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{
        
            Student s = new Student();
            s.setId(Long.parseLong(req.getParameter("studentId")));
            s.setName(req.getParameter("studentName"));
            studentJDBC.updateStudent(s);
            // 刷新页面
            resp.sendRedirect("Student");
        }
    }

HomeworkTeacherServlet.java 教师看到的作业列表，可进行添加和修改操作

package com.javaEE.code.class12.servlet;
    
    import com.javaEE.code.class12.jdbc.HomeworkJDBC;
    import com.javaEE.code.class12.model.Homework;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    import java.util.List;
    
    // 教师看到的作业列表，可进行添加和修改操作
    @WebServlet(name = "HomeworkTeacherServlet", urlPatterns = "/HomeworkTeacher")
    public class HomeworkTeacherServlet extends HttpServlet {
        
        private HomeworkJDBC homeworkJDBC = new HomeworkJDBC();
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            List<Homework> list = homeworkJDBC.selectAll();
            req.setAttribute("list",list);
            req.getRequestDispatcher("/jsp/homework-teacher.jsp").forward(req, resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            req.setCharacterEncoding("utf-8");
    
            // 获取方法名
            String name = req.getParameter("method");
    
            if (name == null || name.isEmpty()) {
        
                throw new RuntimeException("method parameter does not exist");
            }
    
            // 获得当前类的Class对象
            Class c = this.getClass();
            Method method = null;
            try {
        
                // 使用反射机制获取在本类中声明了的方法
                method = getClass().getDeclaredMethod(name, HttpServletRequest.class, HttpServletResponse.class);
                // 反射调用方法
                method.invoke(this, req, resp);
            } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
        
                e.printStackTrace();
            }
        }
    
        protected void addHomework(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            req.setCharacterEncoding("utf-8");
            Homework h = new Homework();
            h.setHomeworkTittle(req.getParameter("title"));
            h.setHomeworkContent(req.getParameter("content"));
            System.out.println(h.toString());
            homeworkJDBC.addHomework(h);
            // 刷新页面
            resp.sendRedirect("HomeworkTeacher");
        }
    
        protected void updateHomework(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            req.setCharacterEncoding("utf-8");
            Homework h = new Homework();
            h.setId(Long.parseLong(req.getParameter("homeworkId")));
            h.setHomeworkTittle(req.getParameter("title"));
            h.setHomeworkContent(req.getParameter("content"));
            homeworkJDBC.updateHomework(h);
            // 刷新页面
            resp.sendRedirect("HomeworkTeacher");
        }
    }

StudentHomeworkServlet.java 学生提交的作业列表

package com.javaEE.code.class12.servlet;
    
    import com.javaEE.code.class12.jdbc.StudentHomeworkJDBC;
    import com.javaEE.code.class12.model.StudentHomework;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.util.List;
    
    @WebServlet(name = "StudentHomeworkServlet", urlPatterns = "/StudentHomework")
    public class StudentHomeworkServlet extends HttpServlet {
        
        private StudentHomeworkJDBC studentHomeworkJDBC = new StudentHomeworkJDBC();
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            List<StudentHomework> list = studentHomeworkJDBC.selectAll();
            req.setAttribute("list",list);
            req.getRequestDispatcher("/jsp/studentHomework.jsp").forward(req, resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            req.setCharacterEncoding("utf-8");
            StudentHomework sh = new StudentHomework();
            sh.setStudentId(Long.parseLong(req.getParameter("studentId")));
            sh.setHomeworkId(Long.parseLong(req.getParameter("homeworkId")));
            sh.setHomeworkTitle(req.getParameter("title"));
            sh.setHomeworkContent(req.getParameter("content"));
            System.out.println(sh.toString());
            studentHomeworkJDBC.addStudentHomework(sh);
            // 刷新页面
    //        doGet(req, resp);
            resp.sendRedirect("HomeworkStudent");
        }
    }

Viewer 层——界面  
index.jsp 首页

<%@ page import="com.javaEE.code.class12.model.StudentHomework" %>
    <%@ page import="java.util.List" %>
    <%@ page import="com.javaEE.code.class12.jdbc.StudentHomeworkJDBC" %>
    <%--
      Created by IntelliJ IDEA.
      User: 
      Date: 2020/2/27
      Time: 15:04
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
      <title>JavaEE-01</title>
      <style>
        #div1 {
        
          height: 100%;
          width: 50%;
          /*float: none;*/
          /*border: black;*/
          margin: 0 auto;
          text-align: center;
        }
      </style>
    </head>
    <body>
    <h2 align="center">基于 Java + Servlet + MySQL 的简易学生作业管理系统</h2>
    <div id="div1" align="center">
      <fieldset>
        <legend align="left">学生作业管理系统</legend>
        <button οnclick="location.href='HomeworkStudent'" type="button">学生登录</button>
            
        <button οnclick="location.href='Student'" type="button">教师登录</button>
      </fieldset>
    </div>
    </button>
    </body>
    </html>

homework-student.jsp 学生查看作业列表，提交作业

teacher.jsp 教师可查看学生列表，添加学生，修改学生信息

<%@ page import="com.javaEE.code.class12.model.StudentHomework" %>
    <%@ page import="java.util.List" %>
    <%@ page import="com.javaEE.code.class12.jdbc.StudentHomeworkJDBC" %>
    <%@ page import="com.javaEE.code.class12.model.Student" %>
    <%--
      Created by IntelliJ IDEA.
      User: 
      Date: 2020/3/8
      Time: 20:20
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
      <title>teacher</title>
      <style>
        #div2, #div3 {
        
          width: 50%;
          float: left;
          /*border: black;*/
          text-align: center;
        }
      </style>
    </head>
    <body>
    <h2 align="center">学生作业管理系统——教师端</h2>
    <hr color="black">
    <h3 align="center">学生列表</h3>
    <div align="center">
      <div>
        <table align="center" width=70% border="1" cellpadding="1" cellspacing="1">
          <tr align="center" height="50" bgcolor="gray">
            <td>学生ID</td>
            <td>学生姓名</td>
            <td>创建时间</td>
            <td>更新时间</td>
          </tr>
          <%
            // 通过网络请求获取结果
            List<Student> list = (List<Student>) request.getAttribute("studentList");
            // 通过StudentHomeworkJDBC对象获取结果
    //    StudentHomeworkJDBC shJDBC = new StudentHomeworkJDBC();
    //    List<StudentHomework> list = shJDBC.selectAll();
            for (Student s : list) {
        
          %>
          <tr align="center" bgcolor="white" height="30">
            <td><%=s.getId()%>
            </td>
            <td><%=s.getName()%>
            </td>
            <td><%=s.getCreateTime()%>
            </td>
            <td><%=s.getUpdateTime()%>
            </td>
          </tr>
          <%
            }
          %>
        </table>
      </div>
      <div>
        <div id="div2">
          <h3>添加学生信息</h3>
          <form action="Student?method=addStudent" method="post" οnsubmit="location.reload()">
            <table align="center">
              <tr>
                <td align="right">学生ID:  </td>
                <td><input type="text" name="studentId"></td>
              </tr>
              <tr>
                <td align="right">学生姓名:  </td>
                <td><input type="text" name="studentName"></td>
              </tr>
              <tr>
                <td><br></td>
                <td><br></td>
              </tr>
              <tr>
                <td></td>
                <td>
                  <input type="submit" value="添加学生信息"/>
                </td>
              </tr>
            </table>
          </form>
        </div>
        <div id="div3">
          <h3>更新学生信息</h3>
          <form action="Student?method=updateStudent" method="post" οnsubmit="location.reload()">
            <table align="center">
              <tr>
                <td align="right">学生ID:  </td>
                <td><input type="text" name="studentId"></td>
              </tr>
              <tr>
                <td align="right">学生姓名:  </td>
                <td><input type="text" name="studentName"></td>
              </tr>
              <tr>
                <td><br></td>
                <td><br></td>
              </tr>
              <tr>
                <td></td>
                <td>
                  <input type="submit" value="更新学生信息"/>
                </td>
              </tr>
            </table>
          </form>
        </div>
      </div>
      <input type="button" name="Submit" οnclick="history.back();" value="返回上一页"> 
      <button οnclick="location.href='index.jsp'" type="button">返回首页</button> 
      <button οnclick="location.href='StudentHomework'" type="button">查看作业提交列表</button> 
      <button οnclick="location.href='HomeworkTeacher'" type="button">查看作业发布列表</button> 
    </div>
    </body>
    </html>

homework-teacher.jsp 教师可查看已发布的作业列表，发布作业和修改作业

<%@ page import="com.javaEE.code.class12.model.StudentHomework" %>
    <%@ page import="java.util.List" %>
    <%@ page import="com.javaEE.code.class12.jdbc.StudentHomeworkJDBC" %>
    <%@ page import="com.javaEE.code.class12.model.Homework" %>
    <%--
      Created by IntelliJ IDEA.
      User: 
      Date: 2020/3/8
      Time: 20:20
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
      <title>student</title>
      <style>
        #div4, #div5 {
        
          width: 50%;
          float: left;
          /*border: black;*/
          text-align: center;
        }
      </style>
    </head>
    <body>
    <h2 align="center">学生作业管理系统——教师端</h2>
    <hr color="black">
    <h3 align="center">作业列表</h3>
    <div>
      <table align="center" width="960" border="1" cellpadding="1" cellspacing="1">
        <tr align="center" height="50" bgcolor="gray">
          <td>作业ID</td>
          <td>作业标题</td>
          <td>作业内容</td>
          <td>创建时间</td>
          <td>更新时间</td>
        </tr>
        <%
          // 通过网络请求获取结果
          List<Homework> list = (List<Homework>) request.getAttribute("list");
          // 通过HomeworkJDBC对象获取结果
    //    HomeworkJDBC shJDBC = new HomeworkJDBC();
    //    List<Homework> list = hJDBC.selectAll();
          for (Homework h : list) {
        
        %>
        <tr align="center" bgcolor="white" height="30">
          <td><%=h.getId()%>
          </td>
          <td><%=h.getHomeworkTittle()%>
          </td>
          <td><%=h.getHomeworkContent()%>
          </td>
          <td><%=h.getCreateTime()%>
          </td>
          <td><%=h.getUpdateTime()%>
          </td>
        </tr>
        <%
          }
        %>
      </table>
    </div>
    <div align="center">
      <div id="div4">
        <h3 align="center">添加作业</h3>
        <div align="center">
          <form action="HomeworkTeacher?method=addHomework" method="post" οnsubmit="location.reload()">
            <table>
              <tr>
                <td align="right">作业标题:  </td>
                <td><input type="text" name="title"></td>
              </tr>
              <tr>
                <td valign="right">作业内容:  </td>
                <td><input type="text" name="content"></td>
              </tr>
              <tr>
                <td><br></td>
                <td><br></td>
              </tr>
              <tr>
                <td></td>
                <td>
                  <input type="button" name="Submit" οnclick="history.back();" value="返回上一页"> 
                  <input type="submit" value="发布作业"/>
                </td>
              </tr>
            </table>
          </form>
        </div>
      </div>
      <div id="div5">
        <h3 align="center">修改作业</h3>
        <div align="center">
          <form action="HomeworkTeacher?method=updateHomework" method="post" οnsubmit="location.reload()">
            <table>
              <tr>
                <td align="right">作业ID:  </td>
                <td><input type="text" name="homeworkId"></td>
              </tr>
              <tr>
                <td align="right">作业标题:  </td>
                <td><input type="text" name="title"></td>
              </tr>
              <tr>
                <td valign="right">作业内容:  </td>
                <td><input type="text" name="content"></td>
              </tr>
              <tr>
                <td><br></td>
                <td><br></td>
              </tr>
              <tr>
                <td></td>
                <td>
                  <input type="button" name="Submit" οnclick="history.back();" value="返回上一页"> 
                  <input type="submit" value="修改作业"/>
                </td>
              </tr>
            </table>
    
          </form>
        </div>
      </div>
      <input type="button" name="Submit" οnclick="history.back();" value="返回上一页"> 
      <button οnclick="location.href='index.jsp'" type="button">返回首页</button> 
      <button οnclick="location.href='StudentHomework'" type="button">查看作业提交列表</button> 
      <button οnclick="location.href='Student'" type="button">查看学生列表</button> 
    </div>
    
    </body>
    </html>

StudentHomework.jsp 教师查看已提交的作业

<%@ page import="com.javaEE.code.class12.model.StudentHomework" %>
    <%@ page import="java.util.List" %>
    <%@ page import="com.javaEE.code.class12.jdbc.StudentHomeworkJDBC" %>
    
    <%--
      Created by IntelliJ IDEA.
      User: wkm
      Date: 2020/2/27
      Time: 09:24
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
      <title>My Homework</title>
    </head>
    <body>
    <h2 align="center">学生作业管理系统——教师端</h2>
    <hr color="black">
    <h3 align="center">作业提交列表</h3>
    <div align="center">
      <table align="center" width="960" border="1"
             bgcolor="black" cellpadding="1" cellspacing="1">
        <tr align="center" bgcolor="gray" height="50">
          <td>ID</td>
          <td>学生学号</td>
          <td>作业编号</td>
          <td>作业标题</td>
          <td>作业内容</td>
          <td>创建时间</td>
        </tr>
        <%
          StudentHomeworkJDBC studentHomeworkJDBC = new StudentHomeworkJDBC();
          List<StudentHomework> list = studentHomeworkJDBC.selectAll();
          for (StudentHomework sh : list) {
        
        %>
        <tr align="center" bgcolor="white" height="30">
          <td><%=sh.getId()%>
          </td>
          <td><%=sh.getStudentId()%>
          </td>
          <td><%=sh.getHomeworkId()%>
          </td>
          <td><%=sh.getHomeworkTitle()%>
          </td>
          <td><%=sh.getHomeworkContent()%>
          </td>
          <td><%=sh.getCreateTime()%>
          </td>
        </tr>
        <%
          }
        %>
      </table>
      <br>
      <input type="button" name="Submit" οnclick="history.back();" value="返回上一页"> 
      <button οnclick="location.href='index.jsp'" type="button">返回首页</button> 
      <button οnclick="location.href='Student'" type="button">查看学生列表</button> 
      <button οnclick="location.href='HomeworkTeacher'" type="button">查看作业发布列表</button> 
    </div>
    
    </body>
    </html>

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