小公司java开发 小型公司java项目实例

 

目录

一.数据库连接步骤（作为一个方法抽取出来）

1.创建一个工具类，专门用来存放频繁使用的代码，避免代码冗余。

2.连接

3.如何使用

4.导入Jar包

5.附上一个测试数据库连接的代码

二.一个简单的登录小项目

1.分层情况

1.分三层，三个包，分别是：dao、service、ui

2.dao

3.service

4.ui

 2.代码实现

---

今日要点：

1.数据库连接步骤

2.学习如何给项目分层分包，每一层做什么功能

一.数据库连接步骤（作为一个方法抽取出来）

1.创建一个工具类，专门用来存放频繁使用的代码，避免代码冗余。

2.连接

连接代码：

public class JdbcUtils {
	

	static {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	
   //1.连接数据库
	public static Connection getConnection() {
		Connection conn = null;
		try {
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/crm?useUnicode=true&characterEncoding=utf8",
					"root", "123456");
		} catch (SQLException e) {
		
			e.printStackTrace();
		}
		return conn;
	}
}

3.如何使用

把下面语句放入方法中即可

Connection conn = null;
conn = JdbcUtils.getConnection();

4.导入Jar包

1）点击项目文件夹右键

2）新建文件夹，命名为lib。注意，此文件夹是和src文件夹是在同一等级的

3）把jar包复制进lib中

4）点击jar包，右键

5）运行

5.附上一个测试数据库连接的代码

package com.gongsi.cn;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class TestJdbc {
	public static void main(String[] args) throws Exception {
				Class.forName("com.mysql.jdbc.Driver");

				Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/crm", "root", "123456");
				
				Statement state = conn.createStatement();
				//SELECT deptno,dname,loc FROM dept
				String sqlAll = "SELECT deptno,dname,loc FROM dept";
				ResultSet rs = state.executeQuery(sqlAll);
	
				while (rs.next()) {
					int deptno = rs.getInt("deptno");
					String dname = rs.getString("dname");
					String loc = rs.getString("loc");
					System.out.println(deptno+"\t"+dname+"\t"+loc);
				}

				rs.close();
				state.close();
				conn.close();
	}
}

注意：

Class.forName("com.mysql.jdbc.Driver");

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/crm", "root", "123456");

这两句根据自己电脑的改。

一定要确保数据库已经开启，并且sql语句是正确的，以及数据库里面有数值。

二.一个简单的登录小项目

1.分层情况

1.分三层，三个包，分别是：dao、service、ui

1）dao：和数据库连接

2）service：业务处理，异常处理

3）ui：界面设计

 

2.dao

创建三个东西：entity包，impl包，接口

1）entity包：里面装的是数据库里的某一个表格。也就是我们要操作的数据

2）impl包：里面装的是这个表格的接口的实现类

3）接口 这个表格的接口。只定义方法，为了使方法名规范。

4）utils是工具类

 3.service

有一个impl包和接口

1)impl 用来装接口的实现类

2）接口 定义接口。接口是一种约束

 4.ui

不需要建包

 2.代码实现

dao包下的：

package com.gongsi.cn.dao.entity;

import java.util.Date;

/*
 * `EMPNO` int(11) NOT NULL DEFAULT '0',
  `ENAME` varchar(10) DEFAULT NULL,
  `PASSWORD` varchar(50) DEFAULT NULL,
  `JOB` varchar(9) DEFAULT NULL,
  `MGR` int(11) DEFAULT NULL,
  `HIREDATE` date DEFAULT NULL,
  `SAL` double DEFAULT NULL,
  `COMM` double DEFAULT NULL,
  `DEPTNO` int(11) DEFAULT NULL,
  PRIMARY KEY (`EMPNO`),
  KEY `FK_DEPTNO` (`DEPTNO`),
 * 
 */
public class Emp {
	private int empno;
	private String ename;
	private String password;
	private String job;
	private int mgr;
	private Date hireDate;
	private double sal;
	private double comm;
	private int deptno;
	@Override
	public String toString() {
		return "Emp [empno=" + empno + ", ename=" + ename + ", password=" + password + ", job=" + job + ", mgr=" + mgr
				+ ", hireDate=" + hireDate + ", sal=" + sal + ", comm=" + comm + ", deptno=" + deptno + "]";
	}
	public Emp() {
		super();
	}
	public Emp(int empno, String ename, String password, String job, int mgr, Date hireDate, double sal, double comm,
			int deptno) {
		super();
		this.empno = empno;
		this.ename = ename;
		this.password = password;
		this.job = job;
		this.mgr = mgr;
		this.hireDate = hireDate;
		this.sal = sal;
		this.comm = comm;
		this.deptno = deptno;
	}
	public int getEmpno() {
		return empno;
	}
	public void setEmpno(int empno) {
		this.empno = empno;
	}
	public String getEname() {
		return ename;
	}
	public void setEname(String ename) {
		this.ename = ename;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getJob() {
		return job;
	}
	public void setJob(String job) {
		this.job = job;
	}
	public int getMgr() {
		return mgr;
	}
	public void setMgr(int mgr) {
		this.mgr = mgr;
	}
	public Date getHireDate() {
		return hireDate;
	}
	public void setHireDate(Date hireDate) {
		this.hireDate = hireDate;
	}
	public double getSal() {
		return sal;
	}
	public void setSal(double sal) {
		this.sal = sal;
	}
	public double getComm() {
		return comm;
	}
	public void setComm(double comm) {
		this.comm = comm;
	}
	public int getDeptno() {
		return deptno;
	}
	public void setDeptno(int deptno) {
		this.deptno = deptno;
	}
	
	
	
}

package com.gongsi.cn.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import com.gongsi.cn.dao.IEmpDao;
import com.gongsi.cn.dao.entity.Emp;
import com.gongsi.cn.dao.utils.JdbcUtils;



public class EmpDaoImpl implements IEmpDao{
	/**
	 * 登录的查询  跟数据库打交道的方法
	 * @param emp 使用实体类对象进行传入参数
	 * @return 查询到的数据
	 */
	public  Emp getEmpByNameAndPassword(Emp emp) {
		Emp resultEmp = null;
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		try {
			
			// 2.得到数据库连接（桥）
			conn = JdbcUtils.getConnection();
			// 3.得到statement接口指向的对象，发送sql语句到数据库中执行，并返回结果集
			// SELECT * FROM emp WHERE ename = '张三' AND `password` = '111'
			String sqlLogin = "SELECT empno,ename,`password`,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE ename = ? AND `password` = ?";
			ps = conn.prepareStatement(sqlLogin);
			ps.setObject(1, emp.getEname());
			ps.setObject(2, emp.getPassword());
			rs = ps.executeQuery();
			if (rs.next()) {
				resultEmp = new Emp();
				resultEmp.setEmpno(rs.getInt("empno"));
				resultEmp.setEname(rs.getString("ename"));
				resultEmp.setPassword(rs.getString("password"));
				resultEmp.setJob(rs.getString("job"));
				resultEmp.setMgr(rs.getInt("mgr"));
				resultEmp.setHireDate(rs.getDate("hiredate"));
				resultEmp.setSal(rs.getDouble("sal"));
				resultEmp.setComm(rs.getDouble("comm"));
				resultEmp.setDeptno(rs.getInt("deptno"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JdbcUtils.closeAll(rs, ps, conn);
		}

		
		return resultEmp;
	}

}

package com.gongsi.cn.dao.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JdbcUtils {
	

	static {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	
   //1.连接数据库
	public static Connection getConnection() {
		Connection conn = null;
		try {
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/crm?useUnicode=true&characterEncoding=utf8",
					"root", "123456");
		} catch (SQLException e) {
		
			e.printStackTrace();
		}
		return conn;
	}
	
//2.增删改
	public static int executeUpdate(String sql,Object...objects ) {
		int rows = -1;
		Connection conn = null;
		PreparedStatement ps = null;
		try {
			conn = JdbcUtils.getConnection();
			ps = conn.prepareStatement(sql);
			if (objects!=null) {
				for (int i = 0; i < objects.length; i++) {
					ps.setObject((i+1), objects[i]);
				}
			}

			rows = ps.executeUpdate();
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JdbcUtils.closeAll(null, ps, conn);
		}
		
		return rows;
	}
	
	
//3.关闭资源
	public static void closeAll(ResultSet rs,Statement state,Connection conn) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if (state != null) {
			try {
				state.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		
	}

}

/**
 * 
 */
package com.gongsi.cn.service;

import com.gongsi.cn.dao.entity.Emp;

/**
 * @author Administrator
 *
 */
public interface IEmpService {

	public Emp loginService(Emp emp) throws  Exception;
}

Service包下的：

package com.gongsi.cn.service.impl;

import com.gongsi.cn.dao.IEmpDao;
import com.gongsi.cn.dao.entity.Emp;
import com.gongsi.cn.dao.impl.EmpDaoImpl;
import com.gongsi.cn.service.IEmpService;

public class EmpServiceImpl implements IEmpService{
	/**
	 * @Autor:Dailyrs
	   @Description 异常检查
	   @param EmpDaoImpl接收的数据
	   @return 返回从EmpDaoImpl接收到的数据
	 */
	public Emp loginService(Emp emp)throws  Exception {
		Emp resultEmp = null;
		IEmpDao get=new EmpDaoImpl();
		resultEmp = get.getEmpByNameAndPassword(emp);
		if (resultEmp==null) {
			throw new Exception("用户名或者密码错误！！");
		}
		return resultEmp;
	}
}

/**
 * 
 */
package com.gongsi.cn.service;

import com.gongsi.cn.dao.entity.Emp;

/**
 * @author Administrator
 *
 */
public interface IEmpService {

	public Emp loginService(Emp emp) throws  Exception;
}

ui包下的：

package com.gongsi.cn.ui;
import java.util.Scanner;
import com.gongsi.cn.dao.entity.Emp;
import com.gongsi.cn.service.IEmpService;
import com.gongsi.cn.service.impl.EmpServiceImpl;
public class LoginView {

	/**
	 * 
	 * @Autor:Dailyrs
	   @Description 登录界面输入数据
	   @param
	   @return 登录成功/登录失败
	 */
	public void loginView() {
		IEmpService em=new EmpServiceImpl();
		Scanner input = new Scanner(System.in);
		System.out.print("请输入用户名：");
		String name = input.next();
		System.out.print("请输入密码:");
		String password = input.next();
		Emp emp = new Emp();
		emp.setEname(name);
		emp.setPassword(password);
		try {
			Emp restulEmp  = em.loginService(emp);
			if (restulEmp!=null) {
				System.out.println("登录成功了！！");
			} 
		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("登录失败了");
		}
		
	}
	
	
	
	
	
	
	
	
	
}

/**
 * 
 */
package com.gongsi.cn.ui;

/**
 * @author Administrator
 *
 */
public class Test {
	public static void main(String[] args) {
		LoginView loginTest=new LoginView();
		loginTest.loginView();
	}

}

不加界面的话，这个代码已经完成

下面是自己画的两个简陋界面。画完之后只需要改两个地方的代码

package com.gongsi.cn.ui;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

import com.gongsi.cn.dao.entity.Emp;
import com.gongsi.cn.service.impl.EmpServiceImpl;

import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.SwingConstants;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Color;

public class LoginFram extends JFrame {

	private JPanel contentPane;
	private JTextField userNameTf;
	private JTextField passwordPf;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					LoginFram frame = new LoginFram();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public LoginFram() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setSize(617, 439);
		this.setLocationRelativeTo(null);
		//setBounds(100, 100, 617, 439);
		
		contentPane = new JPanel();
		contentPane.setBackground(Color.CYAN);
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);
		
		JLabel userNameLbl = new JLabel("用户名");
		userNameLbl.setHorizontalAlignment(SwingConstants.CENTER);
		userNameLbl.setBounds(155, 139, 72, 18);
		contentPane.add(userNameLbl);
		
		userNameTf = new JTextField();
		userNameTf.setBounds(229, 136, 181, 24);
		contentPane.add(userNameTf);
		userNameTf.setColumns(10);
		
		JLabel passwordLbl = new JLabel("密  码");
		passwordLbl.setHorizontalAlignment(SwingConstants.CENTER);
		passwordLbl.setBounds(155, 184, 72, 18);
		contentPane.add(passwordLbl);
		
		passwordPf = new JTextField();
		passwordPf.setBounds(228, 181, 182, 24);
		contentPane.add(passwordPf);
		passwordPf.setColumns(10);
		
		JButton loginBtn = new JButton("登录");
		loginBtn.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				login();
			}
		});
		loginBtn.setBounds(229, 241, 72, 24);
		contentPane.add(loginBtn);
		
		JButton resetBtn = new JButton("重置");
		resetBtn.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
			}
		});
		resetBtn.setBounds(338, 241, 72, 24);
		contentPane.add(resetBtn);
	}
	
	
	protected void login() {
		EmpServiceImpl empServiceImpl=new EmpServiceImpl();
		String userName=userNameTf.getText();
		String password=passwordPf.getText();
		
		Emp emp = new Emp();
		emp.setEname(userName);
		emp.setPassword(password);
		try {
			Emp restulEmp  = empServiceImpl.loginService(emp);
			if (restulEmp!=null) {
				mainFram main=new mainFram();
				main.setVisible(true);
				this.dispose();

			} 
		} catch (Exception e) {
			e.printStackTrace();
			
			System.out.println("登录失败了");
			JOptionPane.showMessageDialog(null, e.getMessage());
		}
		
	}

	
	
	
	
	
}

 

package com.gongsi.cn.ui;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JSplitPane;
import javax.swing.JLabel;
import java.awt.Font;
import java.awt.Color;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class mainFram extends JFrame {

	private JPanel contentPane;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					mainFram frame = new mainFram();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public mainFram() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setSize(1200, 700);
		this.setLocationRelativeTo(null);
		//setBounds(100, 100, 1200, 700);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		contentPane.setLayout(new BorderLayout(0, 0));
		setContentPane(contentPane);
		
		JPanel buttomPanel = new JPanel();
		buttomPanel.setBackground(Color.PINK);
		contentPane.add(buttomPanel, BorderLayout.SOUTH);
		buttomPanel.setLayout(null);
		
		JPanel copyRightPanel = new JPanel();
		copyRightPanel.setBounds(-5, 5, 10, 10);
		buttomPanel.add(copyRightPanel);
		
		JLabel lblNewLabel = new JLabel("版权在这里");
		lblNewLabel.setFont(new Font("宋体", Font.PLAIN, 50));
		copyRightPanel.add(lblNewLabel);
		
		JPanel timePanel = new JPanel();
		timePanel.setBounds(-5, 20, 10, 10);
		buttomPanel.add(timePanel);
		
		JPanel topPanel = new JPanel();
		topPanel.setBackground(Color.PINK);
		contentPane.add(topPanel, BorderLayout.NORTH);
		
		JLabel titleLbl = new JLabel("排队叫号后台管理系统");
		titleLbl.setBackground(Color.PINK);
		titleLbl.setFont(new Font("老報宋", Font.PLAIN, 50));
		topPanel.add(titleLbl);
		
		JSplitPane centerPanel = new JSplitPane();
		contentPane.add(centerPanel, BorderLayout.CENTER);
	}

}

 LoginFram中：

 

 登录成功：

 

 

登录失败：