Java Bean

package xust.demo.stu.domain;

/**
 * Class Student
 * 学生表
 * @author XUST
 * @version 1.0, 2023-04-20
 */
public class Student{


    /**
     * 学号
     */
    private String no;
    public String getNo(){
        return no;
    }

    public void setNo(String newValue){
        no = newValue;
    }
    /**
     * 姓名
     */
    private String name;
    public String getName(){
        return name;
    }

    public void setName(String newValue){
        name = newValue;
    }
    /**
     * 性别
     */
    private String gender;
    public String getGender(){
        return gender;
    }

    public void setGender(String newValue){
        gender = newValue;
    }
    /**
     * 年龄
     */
    private Integer age;
    public Integer getAge(){
        return age;
    }

    public void setAge(Integer newValue){
        age = newValue;
    }
    /**
     * 所在系
     */
    private String dept;
    public String getDept(){
        return dept;
    }

    public void setDept(String newValue){
        dept = newValue;
    }

    @Override
    public String toString() {
    return "{" + "\"no\": " + "\"" + no + "\"" + ", " + "\"name\": " + "\"" + name + "\"" + ", " + "\"gender\": " + "\"" + gender + "\"" + ", " + "\"age\": " + age + ", " + "\"dept\": " + "\"" + dept + "\"" +  "}";
    }
}

package xust.demo.stu.domain;

/**
 * Class Student
 * 学生表
 * @author XUST
 * @version 1.0, 2023-04-20
 */
public class Student{


    /**
     * 学号
     */
    private String no;
    public String getNo(){
        return no;
    }

    public void setNo(String newValue){
        no = newValue;
    }
    /**
     * 姓名
     */
    private String name;
    public String getName(){
        return name;
    }

    public void setName(String newValue){
        name = newValue;
    }
    /**
     * 性别
     */
    private String gender;
    public String getGender(){
        return gender;
    }

    public void setGender(String newValue){
        gender = newValue;
    }
    /**
     * 年龄
     */
    private Integer age;
    public Integer getAge(){
        return age;
    }

    public void setAge(Integer newValue){
        age = newValue;
    }
    /**
     * 所在系
     */
    private String dept;
    public String getDept(){
        return dept;
    }

    public void setDept(String newValue){
        dept = newValue;
    }

    @Override
    public String toString() {
    return "{" + "\"no\": " + "\"" + no + "\"" + ", " + "\"name\": " + "\"" + name + "\"" + ", " + "\"gender\": " + "\"" + gender + "\"" + ", " + "\"age\": " + age + ", " + "\"dept\": " + "\"" + dept + "\"" +  "}";
    }
}

package xust.demo.stu.dao;

import java.sql.*;
import java.util.ArrayList;
import xust.stu.Result;
import xust.stu.ConnectionUtil;
import xust.demo.stu.domain.Student;

public class StudentDaoImpl implements StudentDao{
  public Result init() {
    Result res = new Result(false);

    Connection con = null;
    Statement stmt = null;
    String sql = "create table Student(" +
      "no TEXT primary key," +
      "name TEXT not null," +
      "gender TEXT," +
      "age INTEGER," +
      "dept TEXT" +
      ");";

    con = ConnectionUtil.getConnection();
    if(con != null){
      try {
        stmt = con.createStatement();
        ResultSet rs = stmt.executeQuery(String.format("select count(*) from sqlite_master where type = 'table' and Upper(name) = '%s'", "Student".toUpperCase()));
        while(rs.next()){
          int count = rs.getInt(1);

          if(count == 0 && stmt.executeUpdate(sql) > 0){
            res.code = 0;
          }          
        }
      } catch (Exception e) {
        e.printStackTrace();
        res.message = e.getMessage();
      } finally {
        ConnectionUtil.closeStmt(stmt);
        ConnectionUtil.closeConnection(con);
      }      
    }

    return res;
  }

  /**
   * 对象填充到关系
   */
  private void toR(Student o, PreparedStatement stmt) throws Exception{
    if(o != null && stmt != null){
      String no = o.getNo();
      if(no != null){
        stmt.setString(1, no);       
      }
      String name = o.getName();
      if(name != null){
        stmt.setString(2, name);       
      }
      String gender = o.getGender();
      if(gender != null){
        stmt.setString(3, gender);       
      }
      Integer age = o.getAge();
      if(age != null){
        stmt.setInt(4, age);       
      }
      String dept = o.getDept();
      if(dept != null){
        stmt.setString(5, dept);       
      }
    }
  }

  /**
   * 关系填充到对象
   */
  private Student toO(ResultSet rs) throws Exception{
    Student res = null;

    if(rs != null){
      res = new Student();
      res.setNo(rs.getString("no"));
      res.setName(rs.getString("name"));
      res.setGender(rs.getString("gender"));
      res.setAge(rs.getInt("age"));
      res.setDept(rs.getString("dept"));
    }

    return res;
  }

  public Result create(Student o) {
    Result res = new Result(false);

    Connection con = null;
    PreparedStatement stmt = null;
    String sql = "insert into Student values (?, ?, ?, ?, ?)";
    con = ConnectionUtil.getConnection();
    if (o != null && con != null) {
      try {
        stmt = con.prepareStatement(sql);
        toR(o, stmt);
        if(stmt.executeUpdate() > 0){
          res.code = 0;
        }
      } catch (Exception e) {
        res.message = e.getMessage();
        e.printStackTrace();
      } finally {
        ConnectionUtil.closePstmt(stmt);
        ConnectionUtil.closeConnection(con);
      }
    }

    return res;
  }

  public Result delete(String no) {
    Result res = new Result(false);

    Connection con = null;
    PreparedStatement stmt = null;
    String sql = "delete from Student where no = ?;";
    con = ConnectionUtil.getConnection();
    if(con != null){
      try {

        stmt = con.prepareStatement(sql);
        stmt.setString(1, no);
        res.code = 0;
      } catch (Exception e) {
        res.message = e.getMessage();
        e.printStackTrace();
      } finally {
        ConnectionUtil.closePstmt(stmt);
        ConnectionUtil.closeConnection(con);
      }      
    }

    return res;
  }

  public Result update(Student o) {
    Result res = new Result(false);

    Connection con = null;
    PreparedStatement stmt = null;
    String sql = "update Student set No = ?, Name = ?, Gender = ?, Age = ?, Dept = ? where no = ?";
    con = ConnectionUtil.getConnection();
    if (o != null && con != null) {
      try {

        stmt = con.prepareStatement(sql);
        toR(o, stmt);
        stmt.setString(6, o.getNo());
        if(stmt.executeUpdate() > 0){
          res.code = 0;
        }
      } catch (Exception e) {
        e.printStackTrace();
        res.message = e.getMessage();
      } finally {
        ConnectionUtil.closePstmt(stmt);
        ConnectionUtil.closeConnection(con);
      }
    }

    return res;
  }

  public Result get(String no) {
    Result res = new Result(false);

    Connection con = null;
    PreparedStatement stmt = null;
    String sql = "select * from Student where no = ?";
    con = ConnectionUtil.getConnection();
    if(con != null){
      try {
        stmt = con.prepareStatement(sql);
        stmt.setString(1, no);
        ResultSet rs = stmt.executeQuery();
        Student last = null;
        while (rs.next()) {
          last = new Student();
          last.setNo(rs.getString("no"));
          last.setName(rs.getString("name"));
          last.setGender(rs.getString("gender"));
          last.setAge(rs.getInt("age"));
          last.setDept(rs.getString("dept"));
        }

        res.code = 0;
        res.data = last;
      } catch (Exception e) {
        res.message = e.getMessage();
        e.printStackTrace();
      } finally {
        ConnectionUtil.closePstmt(stmt);
        ConnectionUtil.closeConnection(con);
      }      
    }

    return res;
  }

  public Result getAll() {
    Result res = new Result(false);

    Connection con = null;
    PreparedStatement stmt = null;
    String sql = "select * from Student";
    con = ConnectionUtil.getConnection();
    if(con != null){
      try {
        stmt = con.prepareStatement(sql);
        ResultSet rs = stmt.executeQuery();
        ArrayList<Student> data = new ArrayList<Student>();
        while (rs.next()) {
          Student last = toO(rs);
          data.add(last);
        }

        res.code = 0;
        res.data = data;
      } catch (Exception e) {
        res.message = e.getMessage();
        e.printStackTrace();
      } finally {
        ConnectionUtil.closePstmt(stmt);
        ConnectionUtil.closeConnection(con);
      }      
    }

    return res;
  }
}

package xust.demo;

import java.sql.*;

/**
 * 连接辅助类
 */
public class ConnectionUtil {
  /**
   * 创建连接
   * 
   * @return 连接对象
   */
  public static Connection getConnection() {
    Connection res = null;

    try {
      Class.forName("org.sqlite.JDBC");
      res = DriverManager.getConnection("jdbc:sqlite:stu.db");
    } catch (Exception e) {
      System.err.println(e.getClass().getName() + ": " + e.getMessage());
      System.exit(0);
    }

    return res;
  }

  /**
   * 关闭连接
   * 
   * @param connection 连接对象
   */
  public static void closeConnection(Connection connection) {
    if (connection != null) {
      try {
        connection.close();
      } catch (Exception e) {
        System.err.println(e.getClass().getName() + ": " + e.getMessage());
        System.exit(0);
      }
    }
  }

  /**
   * 关闭语句
   * 
   * @param pstmt 语句对象
   */
  public static void closePstmt(PreparedStatement pstmt) {
    if (pstmt != null) {
      try {
        pstmt.close();
      } catch (Exception e) {
        System.err.println(e.getClass().getName() + ": " + e.getMessage());
        System.exit(0);
      }
    }
  }

  /**
   * 关闭语句
   * 
   * @param pstmt 语句对象
   */
  public static void closeStmt(Statement stmt) {
    if (stmt != null) {
      try {
        stmt.close();
      } catch (Exception e) {
        System.err.println(e.getClass().getName() + ": " + e.getMessage());
        System.exit(0);
      }
    }
  }
}