8.HRMS系统实现

本章内容

一、HRMS系统实现（项目贯穿）

1、项目结构如下图：

2、pom.xml导依赖

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.29</version>
    </dependency>

3、创建配置文件 jdbc.properties

注意该文件不能直接放到src目录下，要放到resources文件下

db.driver=com.mysql.cj.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/hrms?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
db.username=root
db.password=root

4、创建工具类JdbcUtils

package com.woniuxy.util;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;

/**
 * @author ：fengsir
 * @date ：Created in 2023/2/15 12:32
 * @description：连接数据工具类
 * @modified By：
 * @version: 1.0
 */
public class JdbcUtils {
    static Properties properties = new Properties();

    static {
        InputStream inputStream = DBUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
        try {
            properties.load(inputStream);
            Class.forName(properties.getProperty("jdbc.driver"));
        } catch (IOException e) {
            throw new RuntimeException(e);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }

    }

    /**
     * @Description 获取连接(封装到方法中)
     * @Return java.sql.Connection
     * @Author fengSir
     * @Date Create by 2023/2/15 12:44
     */
    public static Connection getconnection() throws Exception {
        String url = properties.getProperty("db.url");
        String user = properties.getProperty("db.username");
        String password = properties.getProperty("db.password");
        Connection conn = DriverManager.getConnection(url, user, password);
        return conn;
    }

    /**
     * @param rs
     * @param pstm
     * @param conn
     * @Description 释放资源
     * @Return void
     * @Author fengSir
     * @Date Create by 2023/2/15 12:45
     */
    public static void release(ResultSet rs, PreparedStatement pstm, Connection conn) throws Exception {
        if (rs != null) {
            rs.close();
        }
        if (pstm != null) {
            pstm.close();
        }
        if (conn != null) {
            conn.close();
        }
    }

}

5、创建泛型接口IBaseDao

package com.woniuxy.dao;

import java.util.List;

public interface IBaseDao<T, K> {

    public int add(T t) throws Exception;

    public int update(T t) throws Exception;

    public List<T> queryAll() throws Exception;

    public T queryById(K k) throws Exception;

    public int delete(K k) throws Exception;

}

6、创建员工dao层接口

public interface IEmployeeDao extends IBaseDao<Employee,Integer>{

}

7、创建dao层实现类

package com.woniuxy.dao;

import com.woniuxy.entity.Employee;
import com.woniuxy.util.JdbcUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

/**
 * @author ：fengsir
 * @date ：Created in 2023/2/15 14:00
 * @description：实现类
 * @modified By：
 * @version: 1.0
 */
public class IEmployeeDaoImpl implements IEmployeeDao {
    private Connection conn = null;
    private PreparedStatement ps = null;
    private ResultSet rs = null;
    private String sql = "";
    @Override
    public int add(Employee employee) throws Exception {
        int i = 0;
        sql = "insert into employee(id,`name`,sex,age) VALUES(0,?,?,?)";
        try {
            conn = JdbcUtils.getconnection();
            ps = conn.prepareStatement(sql);
            ps.setString(1,employee.getEmpName());
            ps.setString(2,employee.getSex());
            ps.setInt(3,employee.getAge());
            i = ps.executeUpdate();
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JdbcUtils.release(rs,ps,conn);
        }
        return i;
    }

    @Override
    public int update(Employee employee) throws Exception {
        int i = 0;
        sql = "update employee set name = ? where id =?";
        try {
            conn = JdbcUtils.getconnection();
            ps = conn.prepareStatement(sql);
            ps.setString(1,employee.getEmpName());
            ps.setInt(2,employee.getEmpId());
            i = ps.executeUpdate();
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JdbcUtils.release(rs,ps,conn);
        }
        return i;
    }

    @Override
    public List<Employee> queryAll() throws Exception {
        List<Employee> list = new ArrayList<>();
        sql = "select * from employee";
        try {
            conn = JdbcUtils.getconnection();
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            while(rs.next()){
                Employee employee = new Employee();
                employee.setEmpId(rs.getInt(1));
                employee.setEmpName(rs.getString(2));
                employee.setSex(rs.getString(3));
                employee.setAge(rs.getInt(4));
                list.add(employee);
            }

        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JdbcUtils.release(rs,ps,conn);
        }
        return list;
    }

    @Override
    public Employee queryById(Integer empId) throws Exception {
        sql = "select * from employee where id=?";
        Employee employee = new Employee();
        try {
            conn = JdbcUtils.getconnection();
            ps = conn.prepareStatement(sql);
            ps.setInt(1,empId);
            rs = ps.executeQuery();
            if(rs.next()){
                employee.setEmpId(rs.getInt(1));
                employee.setEmpName(rs.getString(2));
                employee.setSex(rs.getString(3));
                employee.setAge(rs.getInt(4));
            }

        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JdbcUtils.release(rs,ps,conn);
        }
        return employee;
    }

    @Override
    public int delete(Integer empId) throws Exception {
        int i = 0;
        sql = "delete from employee where id =?";
        try {
            conn = JdbcUtils.getconnection();
            ps = conn.prepareStatement(sql);
            ps.setInt(1,empId);
            i = ps.executeUpdate();
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JdbcUtils.release(rs,ps,conn);
        }
        return i;
    }
}

8、测试，实体类省略

9、添加注册方法引出service层概念

用户在注册时要先判断是否添加过，如果添加过则提示账号已经存在

思维导图