期末测试javaweb,考勤系统后台

package com.hjf.dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.hjf.entity.Course;
import com.hjf.util.DBUtil;

/**
 * 课程Dao
 * Dao层操作数据
 * @author Hu
 *
 */
public class CourseDao {

    /**
     * 添加
     * @param course
     * @return
     */
    public  static boolean add(Course course) {
        String sql = "insert into bumeng(departmentid,department) values('" + course.getDepartmentid() + "','" + course.getDepartment()  + "')";
        //创建数据库链接
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;
        
        try {
            state = conn.createStatement();
            state.executeUpdate(sql);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭连接
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }

    /**
     * 删除
     * 
     * @param id
     * @return
     */
    public boolean delete (String id) {
        boolean f = false;
        String sql = "delete from bumeng where departmentid='" + id + "'";
        
        Connection conn = DBUtil.getConn();
        Statement state = null;
        int a = 0;
        
        try {
            state = conn.createStatement();
            a = state.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }

    /**
     * 修改
     * @param name
     * @param pass
     */
    public boolean update(Course course) {
        String sql = "update bumeng set departmentid='" + course.getDepartmentid() + "', department='" + course.getDepartment() 
            + "' where departmentid='" + course.getDepartmentid() + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;

        try {
            state = conn.createStatement();
            a = state.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }
    
    /**
     * 验证课程名称是否唯一
     * true --- 不唯一
     * @param name
     * @return
     */
    public boolean name(String name) {
        boolean flag = false;
        String sql = "select department from bumeng where departmentid = '" + name+ "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                flag = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        return flag;
    }
    
    /**
     * 通过ID得到课程信息
     * @param id
     * @return
     */
    public Course getCourseById(String number) {
        String sql = "select * from bumeng where departmentid ='" + number + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        Course course = null;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                String departmentid = rs.getString("departmentid");
                String department = rs.getString("department");
                
                
                
                course = new Course(departmentid,department);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return course;
    }
    
    /**
     * 通过name得到Course
     * @param name
     * @return
     */
    public Course getCourseByName(String name) {
        String sql = "select * from bumeng where department ='" + name + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        Course course = null;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                
                
                String departmentid = rs.getString("departmentid");
                String department = rs.getString("department");
                
                
                course = new Course(departmentid,department);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return course;
    }
    
    /**
     * 查找
     * @param name
     * @param teacher
     * @param classroom
     * @return
     */
    public List<Course> search(String departmentid, String department) {
        String sql = "select * from bumeng where ";
        
        if (departmentid != "") {
            sql += "departmentid like '%" + departmentid + "%'";
        }
        if (department != "") {
            sql += "departmentid like '%" + department + "%'";
        }
        
        
        List<Course> list = new ArrayList<>();
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            Course bean = null;
            while (rs.next()) {
                
                String number2 = rs.getString("departmentid");
                String name2 = rs.getString("department");
            
                
                
                bean = new Course(number2,name2);
                list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return list;
    }
    
    /**
     * 全部数据
     * @param name
     * @param teacher
     * @param classroom
     * @return
     */
    public List<Course> list() {
        String sql = "select * from bumeng";
        List<Course> list = new ArrayList<>();
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            Course bean = null;
            while (rs.next()) {
            
                String leibie2 = rs.getString("departmentid");
                String biaoti2 = rs.getString("department");
            
                
                
                bean = new Course( leibie2, biaoti2);
                list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return list;
    }

}
package com.hjf.entity;

public class Course {


    private String departmentid;
    private String department;
    
    
    
    
    
    
    public String getDepartmentid() {
        return departmentid;
    }

    public void setDepartmentid(String departmentid) {
        this.departmentid = departmentid;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public Course() {}
    
    public Course(String departmentid, String department) {
        
        this.departmentid = departmentid;
        this.department = department;
        
        
        
    }
    
    
}
package com.hjf.service;

import java.util.List;

import com.hjf.dao.CourseDao;
import com.hjf.entity.Course;

/**
 * CourseService
 * 服务层
 * @author Hu
 *
 */
public class CourseService {

    CourseDao cDao = new CourseDao();
    
    /**
     * 添加
     * @param course
     * @return
     */
    public boolean add(Course course) {
        CourseDao.add(course);
        return true;
    }
    
    /**
     * 删除
     */
    public void del(String id) {
        cDao.delete(id);
    }
    
    /**
     * 修改
     * @return 
     */
    public void update(Course course) {
        cDao.update(course);
    }
    
    /**
     * 通过ID得到一个Course
     * @return 
     */
    public Course getCourseById(String id) {
        return cDao.getCourseById(id);
    }

    /**
     * 通过Name得到一个Course
     * @return 
     */
    public Course getCourseByName(String biaoti) {
        return cDao.getCourseByName(biaoti);
    }
    
    /**
     * 查找
     * @return 
     */
    public List<Course> search(String number, String name) {
        return cDao.search( number,name);
    }
    
    /**
     * 全部数据
     * @return 
     */
    public List<Course> list() {
        return cDao.list();
    }
}
package com.hjf.servlet;

import java.io.IOException;
import java.util.List;

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 com.hjf.entity.Course;
import com.hjf.service.CourseService;

@WebServlet("/CourseServlet")
public class CourseServlet extends HttpServlet {
    
    private static final long serialVersionUID = 1L;

    CourseService service = new CourseService();
    
    /**
     * 方法选择
     */
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        String method = req.getParameter("method");
        
        if ("adds".equals(method)) {
            add(req, resp);
        } else if ("del".equals(method)) {
            del(req, resp);
        } else if ("update".equals(method)) {
            update(req, resp);
        } else if ("search".equals(method)) {
            search(req, resp);
        } else if ("getcoursebyid".equals(method)) {
            getCourseById(req, resp);
        } else if ("getcoursebyname".equals(method)) {
            getCourseByName(req, resp);
        } else if ("list".equals(method)) {
            list(req, resp);
        }
    }

    /**
     * 添加
     * @param req
     * @param resp
     * @throws IOException 
     * @throws ServletException 
     */
    private void add(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
        req.setCharacterEncoding("utf-8");
        //获取数据
        String departmentid = req.getParameter("departmentid");
        String department = req.getParameter("department");
        
        
        Course course = new Course(departmentid,department);
        
        //添加后消息显示
        if(service.add(course)) {
            req.setAttribute("message", "添加成功");
            req.getRequestDispatcher("adds.jsp").forward(req,resp);
        } else {
            req.setAttribute("message", "部门名重复，请重新录入");
            req.getRequestDispatcher("adds.jsp").forward(req,resp);
        }
    }
    
    /**
     * 全部
     * @param req
     * @param resp
     * @throws ServletException 
     */
    private void list(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        
        List<Course> courses = service.list();
        req.setAttribute("courses", courses);
        req.getRequestDispatcher("list.jsp").forward(req,resp);
    }

    /**
     * 通过ID得到Course
     * @param req
     * @param resp
     * @throws ServletException 
     */
    private void getCourseById(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String id = req.getParameter("departmentid");
        Course course = service.getCourseByName(id);
        req.setAttribute("course", course);
        req.getRequestDispatcher("detail2.jsp").forward(req,resp);
    }

    /**
     * 通过名字查找
     * 跳转至删除
     * @param req
     * @param resp
     * @throws IOException
     * @throws ServletException 
     */
    private void getCourseByName(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String name = req.getParameter("departmentid");
        Course course = service.getCourseByName(name);
        if(course == null) {
            req.setAttribute("message", "查无此课程！");
            req.getRequestDispatcher("del.jsp").forward(req,resp);
        } else {
            req.setAttribute("course", course);
            req.getRequestDispatcher("detail.jsp").forward(req,resp);
        }
    }
    
    /**
     * 删除
     * @param req
     * @param resp
     * @throws IOException
     * @throws ServletException 
     */
    private void del(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String id = req.getParameter("departmentid");
        service.del(id);
        req.setAttribute("message", "删除成功！");
        req.getRequestDispatcher("del.jsp").forward(req,resp);
    }
    
    /**
     * 修改
     * @param req
     * @param resp
     * @throws IOException
     * @throws ServletException 
     */
    private void update(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        
        String leibie = req.getParameter("departmentid");
        String biaoti = req.getParameter("department");

        
        Course course = new Course(leibie,biaoti);
        
        
        service.update(course);
        req.setAttribute("message", "修改成功");
        req.getRequestDispatcher("CourseServlet?method=list").forward(req,resp);
    }
    
    /**
     * 查找
     * @param req
     * @param resp
     * @throws ServletException 
     */
    private void search(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String number = req.getParameter("departmentid");
        String name = req.getParameter("department");
        
        
        List<Course> courses = service.search(number,name);
        req.setAttribute("courses", courses);
        req.getRequestDispatcher("searchlist.jsp").forward(req,resp);
    }
}
package com.hjf.util;

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

/**
 * 数据库连接工具
 * @author Hu
 *
 */
public class DBUtil {
    
    public static String db_url = "jdbc:mysql://localhost:3306/user";
    public static String db_user = "root";
    public static String db_pass = "root";
    
    public static Connection getConn () {
        Connection conn = null;
        
        try {
            Class.forName("com.mysql.jdbc.Driver");//加载驱动
            conn = DriverManager.getConnection(db_url, db_user, db_pass);
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return conn;
    }
    
    /**
     * 关闭连接
     * @param state
     * @param conn
     */
    public static void close (Statement state, Connection conn) {
        if (state != null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    public static void close (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();
            }
        }
    }

    public static void main(String[] args) throws SQLException {
        Connection conn = getConn();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql ="select * from course";
        pstmt = conn.prepareStatement(sql);
        rs = pstmt.executeQuery();
        if(rs.next()){
            System.out.println("空");
        }else{
            System.out.println("不空");
        }
    }
}
package com.servlet;

import java.io.IOException;
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 course.Course;


import dao.userDao;
import entry.user;

/**
 * Servlet implementation class Servlet
 */
@WebServlet("/Servlet")
public class Servlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
     */
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         req.setCharacterEncoding("utf-8");
     
   
            String id = req.getParameter("id");
            String pwd = req.getParameter("pwd");
            String number = req.getParameter("number");
            String name = req.getParameter("name");
            String sex = req.getParameter("sex");
            String clas = req.getParameter("clas");
            String dengji = req.getParameter("dengji");
            Course course = new Course(id,pwd,dengji,name,number,sex,clas);
            userDao.add(course);
            req.getRequestDispatcher("chenggong.jsp").forward(req,resp);    
    }

    

}
package course;

public class Course {
    private String id;
    private String pwd;
    private String number;
    private String name;
    private String sex;
    private String clas;
    private String dengji;
    
    
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public String getClas() {
        return clas;
    }
    public void setClas(String clas) {
        this.clas = clas;
    }
    public String getDengji() {
        return dengji;
    }
    public void setDengji(String dengji) {
        this.dengji = dengji;
    }
    public String getNumber() {
        return number;
    }
    public void setNumber(String number) {
        this.number = number;
    }
    
    public Course() {}
    
    public Course(String id,String pwd,String dengji,String name,String number,String sex,String clas) {
        this.id = id;
        this.pwd = pwd;
        this.name = name;
        this.number = number;
        this.clas = clas;
        this.sex = sex;
        this.dengji = dengji;
        
    }
    

}
package dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import course.Course;

import entry.user;
import util.DBUtil;

public class userDao {
public static boolean add(Course course) {
    String sql = "insert into jiben(id,pwd,role,name,birthday,sex,department) values('" + course.getId() + "','" + course.getPwd() + "','" + course.getDengji() + "','" + course.getName() + "','" + course.getNumber() + "','" + course.getSex() + "','" + course.getClas() + "')";
    //创建数据库链接
    Connection conn = DBUtil.getConn();
    Statement state = null;
    boolean f = false;
    int a = 0;
    
    try {
        state = conn.createStatement();
        state.executeUpdate(sql);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        //关闭连接
        DBUtil.close(state, conn);
    }
    
    if (a > 0) {
        f = true;
    }
    return f;
}
    public static String id(String id,String pwd,String dengji) {
       String f="0";
        String sql = "select * from jiben where id = '" + id + "' and pwd = '"+pwd+"'";
        //
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;       
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            if (rs.next()) {
                f = rs.getString(3);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        return f;
    }
    
}
package entry;

public class user {
private String id;
private String password;
private String dengji;


public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}

public String getDengji() {
    return dengji;
}
public void setDEngji(String dengji) {
    this.dengji = dengji;
}
public user(){}
public user( String password) {
    
    this.password = password;
};
public user(String id, String password,String dengji) {
    super();
    this.id = id;
    this.password = password;
    this.dengji = dengji;
}



    private String departmentid;
    private String department;
    
    
    
    
    
    
    public String getDepartmentid() {
        return departmentid;
    }

    public void setDepartmentid(String departmentid) {
        this.departmentid = departmentid;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public void Course() {}
    
    public void Course(String departmentid, String department) {
        
        this.departmentid = departmentid;
        this.department = department;
        
        
        
    }
    
    
}



package s;

import java.util.List;

import course.Course;
import sdao.CourseDao;

public class service {


        static CourseDao cDao = new CourseDao();
        
        /**
         * 添加
         * @param course
         * @return
         */
        public static boolean add(Course course) {
            CourseDao.add(course);
            return true;
        }
        
        /**
         * 删除
         */
        public static void del(String id) {
            cDao.delete(id);
        }
        
        /**
         * 修改
         * @return 
         */
        public static void update(Course course) {
            cDao.update(course);
        }
        
        /**
         * 通过ID得到一个Course
         * @return 
         */
        public static Course getCourseById(String id) {
            return cDao.getCourseById(id);
        }

        /**
         * 通过Name得到一个Course
         * @return 
         */
        public static Course getCourseByName(String biaoti) {
            return cDao.getCourseByName(biaoti);
        }
        
        /**
         * 查找
         * @return 
         */
        public static List<Course> search(String id,String pwd,String dengji,String name,String number,String sex,String clas) {
            return cDao.search(id,pwd,dengji,name,number,sex,clas);
        }
        
        /**
         * 全部数据
         * @return 
         */
        public static List<Course> list() {
            return cDao.list();
        }
    

}
package sdao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import course.Course;
import util.DBUtil;

public class CourseDao {
    public  static boolean add(Course course) {
        String sql = "insert into jiben(id,pwd,role,name,birthday,sex,department) values('" + course.getId() + "','" + course.getPwd() + "','" + course.getDengji() + "','" + course.getName() + "','" + course.getNumber() + "','" + course.getSex() + "','" + course.getClas() + "')";
        //创建数据库链接
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;
        
        try {
            state = conn.createStatement();
            state.executeUpdate(sql);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭连接
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }

    /**
     * 删除
     * 
     * @param id
     * @return
     */
    public boolean delete (String id) {
        boolean f = false;
        String sql = "delete from jiben where id='" + id + "'";
        
        Connection conn = DBUtil.getConn();
        Statement state = null;
        int a = 0;
        
        try {
            state = conn.createStatement();
            a = state.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }

    /**
     * 修改
     * @param name
     * @param pass
     */
    public boolean update(Course course) {
        String sql = "update jiben set id='" +  course.getId() + "', pwd='" + course.getPwd()+"', role='" + course.getDengji()+"', name='" + course.getName()+"', birthday='" + course.getNumber()+"', sex='" + course.getSex()+"', department='" + course.getClas()+
             "' where id='" +  course.getId() + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;

        try {
            state = conn.createStatement();
            a = state.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }
    
    /**
     * 验证课程名称是否唯一
     * true --- 不唯一
     * @param name
     * @return
     */
    public boolean name(String name) {
        boolean flag = false;
        String sql = "select name from jiben where id = '" + name+ "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                flag = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        return flag;
    }
    
    /**
     * 通过ID得到课程信息
     * @param id
     * @return
     */
    public Course getCourseById(String number) {
        String sql = "select * from jiben where id ='" + number + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        Course course = null;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                String id = rs.getString("id");
                String pwd = rs.getString("pwd");
                String dengji = rs.getString("role");
                String name = rs.getString("name");
                String umber = rs.getString("birthday");
                String sex = rs.getString("sex");
                String clas = rs.getString("department");
                
                course = new Course( id, pwd, dengji,name, umber,sex, clas);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return course;
    }
    
    /**
     * 通过name得到Course
     * @param name
     * @return
     */
    public Course getCourseByName(String name) {
        String sql = "select * from jiben where name ='" + name + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        Course course = null;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                
                String id = rs.getString("id");
                String pwd = rs.getString("pwd");
                String dengji = rs.getString("role");
                String nme = rs.getString("name");
                String umber = rs.getString("birthday");
                String sex = rs.getString("sex");
                String clas = rs.getString("department");
                
                course = new Course( id, pwd, dengji,nme, umber,sex, clas);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return course;
    }
    
    /**
     * 查找
     * @param name
     * @param teacher
     * @param classroom
     * @return
     */
    public List<Course> search(String id,String pwd,String dengji,String name,String number,String sex,String clas) {
        String sql = "select * from jiben where ";
        
        if (id != "") {
            sql += "id like '%" + id + "%'";
        }
        if (pwd != "") {
            sql += "pwd like '%" + pwd + "%'";
        }
        if (dengji != "") {
            sql += "role like '%" + dengji + "%'";
        }
        if (name != "") {
            sql += "name like '%" + name + "%'";
        }
        if (number != "") {
            sql += "birthday like '%" + number + "%'";
        }
        if (sex != "") {
            sql += "sex like '%" + sex + "%'";
        }
        if (clas != "") {
            sql += "department like '%" + clas + "%'";
        }
        
        
        List<Course> list = new ArrayList<>();
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            Course bean = null;
            while (rs.next()) {
                
                String id2 = rs.getString("id");
                String pwd2 = rs.getString("pwd");
                String dengji2 = rs.getString("role");
                String nme2 = rs.getString("name");
                String umber2 = rs.getString("birthday");
                String sex2 = rs.getString("sex");
                String clas2 = rs.getString("department");
                
                bean = new Course( id2, pwd2, dengji2,nme2, umber2,sex2, clas2);
            
                
                
                
                list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return list;
    }
    
    /**
     * 全部数据
     * @param name
     * @param teacher
     * @param classroom
     * @return
     */
    public List<Course> list() {
        String sql = "select * from jiben";
        List<Course> list = new ArrayList<>();
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            Course bean = null;
            while (rs.next()) {
            
                String id2 = rs.getString("id");
                String pwd2 = rs.getString("pwd");
                String dengji2 = rs.getString("role");
                String nme2 = rs.getString("name");
                String umber2 = rs.getString("birthday");
                String sex2 = rs.getString("sex");
                String clas2 = rs.getString("department");
                
                bean = new Course( id2, pwd2, dengji2,nme2, umber2,sex2, clas2);
                list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return list;
    }
}
package serv;

import java.io.IOException;
import java.util.List;

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 sdao.CourseDao;
import course.Course;
import s.service;
/**
 * Servlet implementation class servlet1
 */
@WebServlet("/servlet1")
public class servlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public servlet1() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
     */
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        String method = req.getParameter("method");
        
        if ("add".equals(method)) {
            add(req, resp);
        } else if ("del".equals(method)) {
            del(req, resp);
        } else if ("update".equals(method)) {
            update(req, resp);
        } else if ("search".equals(method)) {
            search(req, resp);
        } else if ("getcoursebyid".equals(method)) {
            getCourseById(req, resp);
        } else if ("getcoursebyname".equals(method)) {
            getCourseByName(req, resp);
        } else if ("list".equals(method)) {
            list(req, resp);
        }
    }

    /**
     * 添加
     * @param req
     * @param resp
     * @throws IOException 
     * @throws ServletException 
     */
    private void add(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
        req.setCharacterEncoding("utf-8");
        //获取数据
        String id = req.getParameter("id");
        String pwd = req.getParameter("pwd");
        String dengji = req.getParameter("role");
        String name = req.getParameter("name");
        String number = req.getParameter("birthday");
        String sex = req.getParameter("sex");
        String clas = req.getParameter("department");
        
        Course course = new Course( id, pwd, dengji,name, number, sex, clas) ;
        
        //添加后消息显示
        if(service.add(course)) {
            req.setAttribute("message", "添加成功");
            req.getRequestDispatcher("add.jsp").forward(req,resp);
        } else {
            req.setAttribute("message", "部门名重复，请重新录入");
            req.getRequestDispatcher("add.jsp").forward(req,resp);
        }
    }
    
    /**
     * 全部
     * @param req
     * @param resp
     * @throws ServletException 
     */
    private void list(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        
        List<Course> courses = service.list();
        req.setAttribute("courses", courses);
        req.getRequestDispatcher("lists.jsp").forward(req,resp);
    }

    /**
     * 通过ID得到Course
     * @param req
     * @param resp
     * @throws ServletException 
     */
    private void getCourseById(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String id = req.getParameter("id");
        Course course = service.getCourseById(id);
        req.setAttribute("course", course);
        req.getRequestDispatcher("detail2s.jsp").forward(req,resp);
    }

    /**
     * 通过名字查找
     * 跳转至删除
     * @param req
     * @param resp
     * @throws IOException
     * @throws ServletException 
     */
    private void getCourseByName(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String name = req.getParameter("name");
        Course course = service.getCourseByName(name);
        if(course == null) {
            req.setAttribute("message", "查无此课程！");
            req.getRequestDispatcher("dels.jsp").forward(req,resp);
        } else {
            req.setAttribute("course", course);
            req.getRequestDispatcher("details.jsp").forward(req,resp);
        }
    }
    
    /**
     * 删除
     * @param req
     * @param resp
     * @throws IOException
     * @throws ServletException 
     */
    private void del(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String id = req.getParameter("id");
        service.del(id);
        req.setAttribute("message", "删除成功！");
        req.getRequestDispatcher("dels.jsp").forward(req,resp);
    }
    
    /**
     * 修改
     * @param req
     * @param resp
     * @throws IOException
     * @throws ServletException 
     */
    private void update(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        
        String id = req.getParameter("id");
        String pwd = req.getParameter("pwd");
        String dengji = req.getParameter("role");
        String name = req.getParameter("name");
        String number = req.getParameter("birthday");
        String sex = req.getParameter("sex");
        String clas = req.getParameter("department");
        
        Course course = new Course( id, pwd, dengji,name, number, sex, clas) ;
        
        
        service.update(course);
        req.setAttribute("message", "修改成功");
        req.getRequestDispatcher("servlet1?method=lists").forward(req,resp);
    }
    
    /**
     * 查找
     * @param req
     * @param resp
     * @throws ServletException 
     */
    private void search(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
        req.setCharacterEncoding("utf-8");
        String id = req.getParameter("id");
        String pwd = req.getParameter("pwd");
        String dengji = req.getParameter("role");
        String name = req.getParameter("name");
        String number = req.getParameter("birthday");
        String sex = req.getParameter("sex");
        String clas = req.getParameter("department");
        
        
        
        
        List<Course> courses = service.search(id,pwd,dengji,name,number,sex,clas);
        req.setAttribute("courses", courses);
        req.getRequestDispatcher("searchlist.jsp").forward(req,resp);
    }
}
package servlet;

import java.io.IOException;
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 course.Course;

import dao.userDao;
import entry.user;


/**
 * Servlet implementation class AddServlet
 */
@WebServlet("/AddServlet")
public class AddServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
   
        
        
        protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
             request.setCharacterEncoding("utf-8");
             //
             
             
             String id = request.getParameter("id");
             String password = request.getParameter("password");
            String dengji = request.getParameter("role");
             
              System.out.println(id);
             System.out.println(password);
             if(!userDao.id(id,password,dengji).equals("0")) {
                 request.setAttribute("message", "登录成功");
                 if(userDao.id(id,password,dengji).equals("1"))
                 request.getRequestDispatcher("chenggong.jsp").forward(request,response);
                 else if(userDao.id(id,password,dengji).equals("2"))
                      request.getRequestDispatcher("teacher.jsp").forward(request,response);
                 else  request.getRequestDispatcher("student.jsp").forward(request,response);
             } else {
                 request.setAttribute("message", "登录失败");
                 request.getRequestDispatcher("houtai.jsp").forward(request,response);
             }
        }
        
    
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            doGet(request, response);
        }

    


    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */


}
package util;
 
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 DBUtil {
     
    public static String db_url = "jdbc:mysql://localhost:3306/user?useSSL=false";
    public static String db_user = "root";
    public static String db_pass = "root";
     
    public static Connection getConn () {
        Connection conn = null;
         
        try {
            Class.forName("com.mysql.jdbc.Driver");//鍔犺浇椹卞姩
            conn = DriverManager.getConnection(db_url, db_user, db_pass);
        } catch (Exception e) {
            e.printStackTrace();
        }
         
        return conn;
    }
     
    /*10鍏抽棴杩炴帴*/
    public static void close (Statement state, Connection conn) {
        if (state != null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
         
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
     
    public static void close (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();
            }
        }
    }
 
    public static void main(String[] args) throws SQLException {
        Connection conn = getConn();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql ="select * from user";
        pstmt = conn.prepareStatement(sql);
        rs = pstmt.executeQuery();
        if(rs.next()){
            System.out.println("123");
        }else{
            System.out.println("456");
        }
    }
}

来源：https://www.cnblogs.com/520520520zl/p/12151737.html