Java Web 学生信息管理系统 - 增删改查 DAO 类代码示例

以下是一个简单的学生信息管理系统的增删改查的DAO类代码示例：\n\njava\nimport java.sql.Connection;\nimport java.sql.PreparedStatement;\nimport java.sql.ResultSet;\nimport java.sql.SQLException;\nimport java.util.ArrayList;\nimport java.util.List;\n\npublic class StudentDAO {\n private Connection connection;\n\n public StudentDAO(Connection connection) {\n this.connection = connection;\n }\n\n public void addStudent(Student student) throws SQLException {\n String query = "INSERT INTO students (id, name, age) VALUES (?, ?, ?)";\n PreparedStatement statement = connection.prepareStatement(query);\n statement.setInt(1, student.getId());\n statement.setString(2, student.getName());\n statement.setInt(3, student.getAge());\n statement.executeUpdate();\n statement.close();\n }\n\n public void deleteStudent(int id) throws SQLException {\n String query = "DELETE FROM students WHERE id = ?";\n PreparedStatement statement = connection.prepareStatement(query);\n statement.setInt(1, id);\n statement.executeUpdate();\n statement.close();\n }\n\n public void updateStudent(Student student) throws SQLException {\n String query = "UPDATE students SET name = ?, age = ? WHERE id = ?";\n PreparedStatement statement = connection.prepareStatement(query);\n statement.setString(1, student.getName());\n statement.setInt(2, student.getAge());\n statement.setInt(3, student.getId());\n statement.executeUpdate();\n statement.close();\n }\n\n public Student getStudent(int id) throws SQLException {\n String query = "SELECT * FROM students WHERE id = ?";\n PreparedStatement statement = connection.prepareStatement(query);\n statement.setInt(1, id);\n ResultSet resultSet = statement.executeQuery();\n\n if (resultSet.next()) {\n String name = resultSet.getString("name");\n int age = resultSet.getInt("age");\n return new Student(id, name, age);\n }\n\n resultSet.close();\n statement.close();\n return null;\n }\n\n public List<Student> getAllStudents() throws SQLException {\n List<Student> students = new ArrayList<>();\n String query = "SELECT * FROM students";\n PreparedStatement statement = connection.prepareStatement(query);\n ResultSet resultSet = statement.executeQuery();\n\n while (resultSet.next()) {\n int id = resultSet.getInt("id");\n String name = resultSet.getString("name");\n int age = resultSet.getInt("age");\n students.add(new Student(id, name, age));\n }\n\n resultSet.close();\n statement.close();\n return students;\n }\n}\n\n\n这是一个简单的DAO类，用于对学生信息进行增删改查操作。其中，使用了PreparedStatement来执行SQL语句，并通过Connection对象来获取数据库连接。在增加、删除、更新和查询学生信息时，都使用了相应的SQL语句，并将参数设置到PreparedStatement对象中。在查询学生信息时，使用ResultSet对象获取查询结果，并将结果封装成Student对象。在获取所有学生信息时，使用List集合存储多个Student对象，并将其返回。