jsp+eclipse+tomcat+mysql请假审批系统

请假审批系统是一个常见的办公自动化系统，下面是使用JSP+Servlet+Eclipse+Tomcat+MySQL实现的简单的请假审批系统的开发步骤：

1. 确定系统需求：请假申请、审批流程、数据存储等。
2. 设计数据库：创建请假表、用户表等。
3. 搭建开发环境：安装Eclipse、Tomcat、MySQL等。
4. 创建项目：在Eclipse中创建一个动态Web项目。
5. 编写代码：实现请假申请、审批、查询等功能。
6. 测试系统：在Tomcat上运行系统，进行测试和调试。
7. 部署系统：将系统部署到服务器上，供用户使用。

具体实现步骤如下：

1. 设计数据库

请假表（leave）：

| 字段名 | 数据类型 | 描述 |
|------------|----------|------------|
| id | int | 请假编号 |
| user_id | int | 申请人编号 |
| start_time | datetime | 开始时间 |
| end_time | datetime | 结束时间 |
| reason | varchar | 请假事由 |
| status | int | 审批状态 |

用户表（user）：

| 字段名 | 数据类型 | 描述 |
|---------|----------|----------|
| id | int | 用户编号 |
| name | varchar | 用户名 |
| account | varchar | 账号 |
| password| varchar | 密码 |

2. 搭建开发环境

1. 下载并安装Eclipse
2. 下载并安装Tomcat
3. 下载并安装MySQL

3. 创建项目

在Eclipse中创建一个动态Web项目，选择Tomcat作为服务器，选择JSP作为页面技术，选择MySQL作为数据库。

4. 编写代码

1. 创建数据库连接

package util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/leave_system?useUnicode=true&characterEncoding=utf8&useSSL=false";
    private static final String USER = "root";
    private static final String PASSWORD = "123456";

    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }
}

2. 编写登录功能

package servlet;

import dao.UserDAO;
import entity.User;
import util.DBUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;

@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        String account = request.getParameter("account");
        String password = request.getParameter("password");

        try (Connection conn = DBUtil.getConnection()) {
            User user = new UserDAO().getUser(conn, account, password);
            if (user != null) {
                request.getSession().setAttribute("user", user);
                response.sendRedirect("main.jsp");
            } else {
                response.sendRedirect("index.jsp?error=1");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

3. 编写请假申请功能

package servlet;

import dao.LeaveDAO;
import entity.Leave;
import entity.User;
import util.DBUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;

@WebServlet("/apply")
public class ApplyServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        User user = (User) request.getSession().getAttribute("user");
        String startTime = request.getParameter("start_time");
        String endTime = request.getParameter("end_time");
        String reason = request.getParameter("reason");

        Leave leave = new Leave();
        leave.setUserId(user.getId());
        leave.setStartTime(startTime);
        leave.setEndTime(endTime);
        leave.setReason(reason);

        try (Connection conn = DBUtil.getConnection()) {
            new LeaveDAO().addLeave(conn, leave);
            response.sendRedirect("main.jsp");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

4. 编写请假审批功能

package servlet;

import dao.LeaveDAO;
import entity.Leave;
import util.DBUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

@WebServlet("/approve")
public class ApproveServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        int leaveId = Integer.parseInt(request.getParameter("leave_id"));
        int status = Integer.parseInt(request.getParameter("status"));

        try (Connection conn = DBUtil.getConnection()) {
            new LeaveDAO().updateLeaveStatus(conn, leaveId, status);
            response.sendRedirect("main.jsp");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        int userId = Integer.parseInt(request.getParameter("user_id"));

        try (Connection conn = DBUtil.getConnection()) {
            List<Leave> list = new LeaveDAO().getLeavesByUserId(conn, userId);
            request.setAttribute("list", list);
            request.getRequestDispatcher("approve.jsp").forward(request, response);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

5. 编写查询请假记录功能

package servlet;

import dao.LeaveDAO;
import entity.Leave;
import entity.User;
import util.DBUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

@WebServlet("/query")
public class QueryServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        int userId = Integer.parseInt(request.getParameter("user_id"));

        try (Connection conn = DBUtil.getConnection()) {
            List<Leave> list = new LeaveDAO().getLeavesByUserId(conn, userId);
            request.setAttribute("list", list);
            request.getRequestDispatcher("query.jsp").forward(request, response);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

6. 测试系统

在Eclipse中启动Tomcat服务器，浏览器中访问http://localhost:8080/leave_system/index.jsp，输入账号密码进行登录，测试请假申请、审批、查询等功能。

7. 部署系统

将项目打包成.war文件，上传到服务器上，解压并部署到Tomcat服务器中。完成后，用户可以通过浏览器访问部署好的系统。