荐 Java——JDBC和DbUtils

蒂花之秀 12天前   阅读数 11 0

1. 学生管理系统使用JdbcUitl,BaseDao完成数据持久化操作

1.1 Student实体类

public class Student {
    private Integer id;
    private String name;
    private Integer age;
    private Boolean gender;
    private Float score;
    private String address;

    public Student() {
    }

    public Student(String name, Integer age, Boolean gender, Float score, String address) {
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.score = score;
        this.address = address;
    }

    public Student(Integer id, String name, Integer age, Boolean gender, Float score, String address) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.score = score;
        this.address = address;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Boolean getGender() {
        return gender;
    }

    public void setGender(Boolean gender) {
        this.gender = gender;
    }

    public Float getScore() {
        return score;
    }

    public void setScore(Float score) {
        this.score = score;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", gender=" + gender +
                ", score=" + score +
                ", address='" + address + '\'' +
                '}';
    }
}

1.2 StudentDao规范

public interface StudentDao {
    /** * 添加学生方法要求,参数为Student类对象, 返回值为int类型,操作成功返回1, 失败 * 返回0 * * @param student Student类对象 * @return 添加成功返回1,否则返回0 */
    int addStudent(Student student);

    /** * 根据指定ID删除对应的学生 * * @param id 指定的ID * @return 删除成功返回1,否则返回0 */
    int deleteStudent(int id);

    /** * 修改学生信息,传入的参数是一个Student类对象 * * @param student Student类对象 * @return 更新成功返回1,否则返回0 */
    int updateStudent(Student student);

    /** * 查询指定ID的学生,没有找到返回null * * @param id 指定的ID号 * @return 查询成功返回Student类对象,失败返回null */
    Student findStudentById(int id);

    /** * 查询当前数据库中所有学生信息 * * @return 返回值List集合,如果没有数据返回null */
    List<Student> findAllStudent();
}

1.3 StudentDaoImpl实现

public class StudentDaoImpl extends BaseDao implements StudentDao {
    @Override
    public int addStudent(Student student) {
        String sql = "insert into student(name, age, gender, score, address) value (?, ?, ?, ?, ?)";
        Object[] parameters = {student.getName(), student.getAge(), student.getGender()
                , student.getScore(), student.getAddress()};

        return super.update(sql, parameters);
    }

    @Override
    public int deleteStudent(int id) {
        String sql = "delete from student where id = " + id;

        return super.update(sql, null);
    }

    @Override
    public int updateStudent(Student student) {
        String sql = "update student set name = ?, age = ?, gender = ?, score = ?, address = ? where id = ?";
        Object[] parameters = {student.getName(), student.getAge(), student.getGender()
                , student.getScore(), student.getAddress(), student.getId()};

        return super.update(sql, parameters);
    }

    @Override
    public Student findStudentById(int id) {
        String sql = "select * from student where id = " + id;

        Student student = super.queryBean(sql, null, Student.class);

        return student;
    }

    @Override
    public List<Student> findAllStudent() {
        String sql = "select * from student";

        return super.queryBeanList(sql, null, Student.class);
    }
}

1.4 StudentService规范

public interface StudentService {
    /* 增删改查排序 */

    /** * Service层规定的添加学生方法,返回值类型是boolean * * @param student Student类对象 * @return 添加成功返回true,失败返回false */
    boolean addStudent(Student student);

    /** * 删除指定ID学生 * * @param id 指定学生的ID * @return 删除成功返回true,失败返回false */
    boolean deleteStudentById(Integer id);

    /** * 更新学生信息 * * @param student 需要更新信息的一个Student类对象 * @return 更新成功返回true,失败返回false */
    boolean updateStudent(Student student);

    /** * 查询指定ID的学生 * * @param id 指定的学生的ID号 * @return Student类对象,没有找到返回null */
    Student findStudentById(Integer id);

    /** * 查询所有的学生类对象,存储于List集合中 * * @return List集合,没有数据返回null */
    List<Student> findAllStudents();

    /** * 按照提供的方法,排序学生信息保存到List集合中 * * @param comparator Comparator函数式接口要求规范 * @return List集合,排序之后的学生数据,没有数据返回null */
    List<Student> sortUsingCompare(Comparator<Student> comparator);
}

1.5 StudentServiceImpl实现

public class StudentServiceImpl implements StudentService {

    /** * 准备一个StudentDao层的实现类对象,帮助操作数据库 */
    StudentDao studentDao = new StudentDaoImpl();

    @Override
    public boolean addStudent(Student student) {
        return studentDao.addStudent(student) != 0;
    }

    @Override
    public boolean deleteStudentById(Integer id) {
        return studentDao.deleteStudent(id) != 0;
    }

    @Override
    public boolean updateStudent(Student student) {
        return studentDao.updateStudent(student) != 0;
    }

    @Override
    public Student findStudentById(Integer id) {
        return studentDao.findStudentById(id);
    }

    @Override
    public List<Student> findAllStudents() {
        return studentDao.findAllStudent();
    }

    @Override
    public List<Student> sortUsingCompare(Comparator<Student> comparator) {
        List<Student> list = studentDao.findAllStudent();

        if (list != null) {
            list.sort(comparator);
        }

        return list;
    }
}

1.6 StudentView规范

public interface StudentView {
    /** * 提示用户输入ID */
    void inputStudentId();

    /** * 提示用户输入醒目 */
    void inputStudentName();

    /** * 提示用户输入年龄 */
    void inputStudentAge();

    /** * 提示用户输入性别 */
    void inputStudentGender();

    /** * 提示用户输入成绩 */
    void inputStudentScore();

    /** * 提示用户输入住址 */
    void inputStudentAddress();

    /** * 展示一个学生信息 * * @param student Student类对象 */
    void showStudentInfo(Student student);

    /** * 删除确认提示 */
    void deleteConfirm();

    /** * 操作取消 */
    void operationCancel();

    /** * Not Found!!! ==> 404 */
    void notFound();

    /** * 展示List集合的中的Student类对象 * @param students List集合 */
    void showStudentList(List<Student> students);

    /** * 排序选择提示 */
    void sortOperationChoose();

    /** * 修改学生菜单 * @param student Student */
    void modifyStudentMenu(Student student);

    /** * 选择错误提示 */
    void chooseError();

    /** * 主菜单,主界面 */
    void mainMenu();
}

1.7 StudentViewImpl实现

public class StudentViewImpl implements StudentView {

    @Override
    public void inputStudentId() {
        System.out.println("请输入学生的ID号:");
    }

    @Override
    public void inputStudentName() {
        System.out.println("请输入学生的姓名:");
    }

    @Override
    public void inputStudentAge() {
        System.out.println("请输入学生的年龄:");
    }

    @Override
    public void inputStudentGender() {
        System.out.println("请输入学生的性别 true => 男 false => 女:");
    }

    @Override
    public void inputStudentScore() {
        System.out.println("请输入学生的成绩:");
    }

    @Override
    public void inputStudentAddress() {
        System.out.println("请输入学生的地址:");
    }

    @Override
    public void showStudentInfo(Student student) {
        System.out.println(student);
    }

    @Override
    public void deleteConfirm() {
        System.out.println("确定删除吗? true or false");
    }

    @Override
    public void operationCancel() {
        System.out.println("操作取消");
    }

    @Override
    public void notFound() {
        System.out.println("查无此人");
    }

    @Override
    public void showStudentList(List<Student> students) {
        for (Student student : students) {
            System.out.println(student);
        }
    }

    @Override
    public void sortOperationChoose() {
        System.out.println("1. 年龄升序");
        System.out.println("2. 成绩降序");
    }

    @Override
    public void modifyStudentMenu(Student student) {
        System.out.println("ID:" + student.getId() + " Name:" + student.getName());
        System.out.println("Age:" + student.getAge() + " Gender:" + (student.getGender() ? "男" : "女"));
        System.out.println("Score:" + student.getScore() + " Address:" + student.getAddress());
        System.out.println("1. 修改学生的名字");
        System.out.println("2. 修改学生的年龄");
        System.out.println("3. 修改学生的性别");
        System.out.println("4. 修改学生的成绩");
        System.out.println("5. 修改学生的地址");
        System.out.println("6. 退出保存");
    }

    @Override
    public void chooseError() {
        System.out.println("选择错误!!!");
    }

    @Override
    public void mainMenu() {
        System.out.println("1. 添加学生");
        System.out.println("2. 删除指定ID学生");
        System.out.println("3. 修改指定ID学生");
        System.out.println("4. 查询指定ID学生");
        System.out.println("5. 查询所有学生");
        System.out.println("6. 按照条件排序学生信息");
        System.out.println("7. 退出");
    }
}

1.8 StudentController实现

public class StudentController {

    /** * StudentService层实现类对象,提供服务 */
    private StudentService studentService = new StudentServiceImpl();

    /** * StudentView 界面层实现类对象,提供界面展示 */
    private StudentView studentView = new StudentViewImpl();

    private Scanner scanner = new Scanner(System.in);

    /** * 添加学生 */
    public void addStudent() {
        studentView.inputStudentName();
        String name = scanner.next();

        studentView.inputStudentAge();
        int age = scanner.nextInt();

        studentView.inputStudentGender();
        boolean gender = scanner.nextBoolean();

        studentView.inputStudentScore();
        float score = scanner.nextFloat();

        studentView.inputStudentAddress();
        String address = scanner.next();

        Student student = new Student(name, age, gender, score, address);

        studentService.addStudent(student);
    }

    /** * 删除学生 */
    public void deleteStudent() {
        studentView.inputStudentId();
        int id = scanner.nextInt();

        Student student = studentService.findStudentById(id);

        if (null == student) {
            studentView.notFound();
            return;
        }

        studentView.showStudentInfo(student);
        studentView.deleteConfirm();

        if (scanner.nextBoolean()) {
            studentService.deleteStudentById(id);
        } else {
            studentView.operationCancel();
        }
    }

    /** * 修改指定ID学生 */
    public void modifyStudentById() {
        studentView.inputStudentId();
        int id = scanner.nextInt();

        Student student = studentService.findStudentById(id);

        if (null == student) {
            studentView.notFound();
            return;
        }

        int choose = 0;
        boolean flag = false;

        while (true) {
            studentView.modifyStudentMenu(student);
            choose = scanner.nextInt();

            switch (choose) {
                case 1:
                    studentView.inputStudentName();
                    String name = scanner.next();

                    student.setName(name);
                    break;
                case 2:
                    studentView.inputStudentAge();
                    int age = scanner.nextInt();

                    student.setAge(age);
                    break;
                case 3:
                    studentView.inputStudentGender();
                    boolean gender = scanner.nextBoolean();

                    student.setGender(gender);

                    break;
                case 4:
                    studentView.inputStudentScore();
                    float score = scanner.nextFloat();

                    student.setScore(score);
                    break;
                case 5:
                    studentView.inputStudentAddress();
                    String address = scanner.next();

                    student.setAddress(address);
                    break;
                case 6:
                    flag = true;
                    break;
                default:
                    studentView.chooseError();
                    break;
            }

            if (flag) {
                studentService.updateStudent(student);
                break;
            }
        }

    }

    /** * 查询指定ID学生 */
    public void findStudentById() {
        studentView.inputStudentId();
        int id = scanner.nextInt();

        Student student = studentService.findStudentById(id);

        if (student != null) {
            studentView.showStudentInfo(student);
        } else {
            studentView.notFound();
        }
    }

    /** * 查询所有学生 */
    public void findAllStudent() {
        List<Student> list = studentService.findAllStudents();

        if (list != null) {
            studentView.showStudentList(list);
        } else {
            studentView.notFound();
        }
    }

    /** * 按照条件排序 */
    public void sort() {

        studentView.sortOperationChoose();
        int choose = scanner.nextInt();

        List<Student> list = null;
        switch (choose) {
            case 1:
                // 年龄升序
                list = studentService.sortUsingCompare(Comparator.comparingInt(Student::getAge));
                break;
            case 2:
                // 成绩降序
                list = studentService.sortUsingCompare((stu1, stu2) -> {
                    BigDecimal bigDecimal1 = new BigDecimal(stu1.getScore() + "");
                    BigDecimal bigDecimal2 = new BigDecimal(stu2.getScore() + "");

                    return bigDecimal2.compareTo(bigDecimal1);
                });
                break;
            default:
                studentView.chooseError();
                break;
        }

        if (list != null) {
            studentView.showStudentList(list);
        } else {
            studentView.notFound();
        }
    }

    public void mainMenu() {
        studentView.mainMenu();
    }

    public void chooseError() {
        studentView.chooseError();
    }

}

1.9 StudentProject main方法

public class MainProject {

    private static Scanner scanner = new Scanner(System.in);

    private static StudentController studentController = new StudentController();

    public static void main(String[] args) {
        int choose = 0;
        boolean flag = true;

        while (flag) {
            studentController.mainMenu();
            choose = scanner.nextInt();

            switch (choose) {
                case 1:
                    studentController.addStudent();
                    break;
                case 2:
                    studentController.deleteStudent();
                    break;
                case 3:
                    studentController.modifyStudentById();
                    break;
                case 4:
                    studentController.findStudentById();
                    break;
                case 5:
                    studentController.findAllStudent();
                    break;
                case 6:
                    studentController.sort();
                    break;
                case 7:
                    flag = false;
                    break;
                default:
                    studentController.chooseError();
                    break;
            }
        }
    }
}

2. 轻量级数据库ORM框架DbUtils

2.1 DbUtils介绍

Apache组织下的一个轻量级ORM框架
	Commons DbUtils: JDBC Utility Component
两个核心方法
	update方法 ==> insert,update,delete
	query方法 ==> select

一个核心类
	QueryRunner DbUtils的核心类

2.2 DbUtils ORM工具使用

import com.qfedu.b_studentsys.entity.Student;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.*;
import org.junit.Test;
import util.JdbcUtil;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

/** * DbUtils ORM框架演示 * */
public class DbUtilsTest {
    @Test
    public void testInsert() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. 插入数据到Student数据表中
        String sql = "insert into student(name, age, gender, score, address) value(?, ?, ?, ?, ?)";
        Object[] parameters = {"lb", 20, true, 82, "lnas"};

        // 3. 获取数据库连接
        Connection connection = JdbcUtil.getConnection();

        // 4. 执行Update方法
        runner.update(connection, sql, parameters);

        JdbcUtil.close(connection);
    }

    /** * 了解操作方式, ResultSetHandler */
    @Test
    public void testQuery1() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id = 1";

        Connection connection = JdbcUtil.getConnection();

        /* ResultSetHandler 核心接口 ResultSet结果集 Handler处理, 核心方法 handler(ResultSet rs) */
        Student student = runner.query(connection, sql, rs -> {
            Student stu = null;
            if (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                boolean gender = rs.getBoolean("gender");
                float score = rs.getFloat("score");
                String address = rs.getString("address");

                stu = new Student(id, name, age, gender, score, address);
            }
            return stu;
        });

        System.out.println(student);
        JdbcUtil.close(connection);
    }

    /** * BeanHandler */
    @Test
    public void queryBean() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id = 1";

        Connection connection = JdbcUtil.getConnection();

        /* BeanHandler: 处理符合JavaBean规范的类对象,传入参数是对应JavaBean规范 Class对象 */
        Student student = runner.query(connection, sql, new BeanHandler<>(Student.class));

        System.out.println(student);

        JdbcUtil.close(connection);
    }

    /** * BeanListHandler */
    @Test
    public void queryBeanList() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id > ?";

        Connection connection = JdbcUtil.getConnection();

        /* BeanListHandler: 处理符合JavaBean规范的实体类,并且返回值是一个List集合 包含制定的JavaBean实体类 */
        List<Student> list = runner.query(connection, sql, new BeanListHandler<>(Student.class), 2);

        for (Student student : list) {
            System.out.println(student);
        }
        JdbcUtil.close(connection);
    }

    /** * ArrayHandler */
    @Test
    public void queryArray() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id = 1";

        Connection connection = JdbcUtil.getConnection();

        /* ArrayHandler: 查询一个数据行,数据行中的所有数据整合成一个Object类型数组返回 */
        Object[] values = runner.query(connection, sql, new ArrayHandler());

        System.out.println(Arrays.toString(values));

        JdbcUtil.close(connection);
    }

    /** * ArrayListHandler */
    @Test
    public void queryArrayList() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id > ?";

        Connection connection = JdbcUtil.getConnection();

        /* ArrayListHandler: 查询结果集中所有数据行,每一行数据对应一个Object类型数组,存储在List集合中 */
        List<Object[]> list = runner.query(connection, sql, new ArrayListHandler(), 2);

        for (Object[] values : list) {
            System.out.println(Arrays.toString(values));
        }
        JdbcUtil.close(connection);
    }

    /** * MapHandler */
    @Test
    public void queryMap() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id = 1";

        Connection connection = JdbcUtil.getConnection();

        /* MapHandler: 处理一个数据行,数据行中字段是对应Key,字段对应数据是value,组成一个Map双边队列 */
        Map<String, Object> map = runner.query(connection, sql, new MapHandler());

        System.out.println(map);
    }

    /** * MapListHandler */
    @Test
    public void queryMapList() throws SQLException {
        // 1. DbUtils核心类 QueryRunner对象
        QueryRunner runner = new QueryRunner();

        // 2. SQL语句
        String sql = "select * from student where id > ?";

        Connection connection = JdbcUtil.getConnection();

        /* MapListHandler: 结果集中所有的数据行,每一行对应一个Map对象,字段名为Key,字段对应的数据为value,所有数据行存储 在List中 */
        List<Map<String, Object>> mapList = runner.query(connection, sql, new MapListHandler(), 2);

        for (Map<String, Object> map : mapList) {
            System.out.println(map);
        }
    }
}

2.3 ResultHandler以及其子类

ResultSetHandler 核心接口
	ResultSet结果集 Handler处理,	
	核心方法 handler(ResultSet rs)
 
BeanHandler: 
	处理符合JavaBean规范的类对象,传入参数是对应JavaBean规范 Class对象

BeanListHandler: 
	处理符合JavaBean规范的实体类,并且返回值是一个List集合包含制定的JavaBean实体类

ArrayHandler: 
	查询一个数据行,数据行中的所有数据整合成一个Object类型数组返回

ArrayListHandler: 
	查询结果集中所有数据行,每一行数据对应一个Object类型数组,存储在List集合中

MapHandler: 
	处理一个数据行,数据行中字段是对应Key,字段对应数据是value,组成一个Map双边队列

MapListHandler: 
	结果集中所有的数据行,每一行对应一个Map对象,字段名为Key,字段对应的数据为value,所有数据行存储在List中
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