I am not using a maven project here, I am using a general web project, so I need to download and add the framework packages I need to use. In the project, I must pay attention to the configuration of the environment. I am using jre1.7

1 Create a new project

2 Establish the MVC management package and import the corresponding rack package servlet

3 Create the entity class teacher.java corresponding to the database

public class Teacher {
            private  int  tid;
            private  String tname;
            private  String tpsw;
            public int getTid() {
                return tid;
            }
            public void setTid(int tid) {
                this.tid = tid;
            }
            public String getTname() {
                return tname;
            }
            public void setTname(String tname) {
                this.tname = tname;
            }
            public String getTpsw() {
                return tpsw;
            }
            public void setTpsw(String tpsw) {
                this.tpsw = tpsw;
            }
            public Teacher(String tname, String tpsw) {
                super();
                this.tname = tname;
                this.tpsw = tpsw;
            }
            public Teacher(int tid, String tname, String tpsw) {
                super();
                this.tid = tid;
                this.tname = tname;
                this.tpsw = tpsw;
            }
            public Teacher() {
                super();
            }
}

4 Write a new login.jsp file in WebContent Login box

1

2

5 Configure the web.xml file corresponding to the form request login

web .xml file

Note: When configuring, must be before, otherwise an error will be reported

<!-- 提交登錄請求 -->
  <servlet>
    <servlet-name>login</servlet-name>
    <servlet-class>com.zr.controller.LoginController</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>login</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>

6 Write the corresponding request entity class LoginController.java: Inherit HttpServlet and rewrite the doget(), dopost() methods, according to the different method requests Call the doget or dopost method

LoginController.java

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.zr.model.Teacher;
import com.zr.service.valiDateService;
import com.zr.serviceIm.valiDateServiceImpl;
public class LoginController   extends  HttpServlet{
protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
         throws ServletException, IOException {
                super.doPost(req, resp);
            }
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
          throws ServletException, IOException {
           //獲取前臺form表單的input輸入框
           String tname=req.getParameter("tname");
           String tpsw=req.getParameter("tpsw");
           Teacher tc=new Teacher();
           tc.setTname(tname);
           tc.setTpsw(tpsw);
           valiDateService vds=new valiDateServiceImpl();
          Teacher t=    vds.valiDateTeacher(tc);
        HttpSession  session=req.getSession();
        session.setAttribute("teacher", t);
        if (t!=null) {
            //返回的不是空值,重定向到登錄成功界面
            req.getRequestDispatcher("main.jsp").forward(req, resp);
        } else {
            //返回空值,請求轉(zhuǎn)發(fā)到登錄界面
            resp.sendRedirect("login.jsp");
        }      
            }
}

7 Write from the background dao layer to the control layer

public interface TeacherDao {
    
    /**
     * 驗證老師是否存在
     * @param tc
     * @return
     */
    public Teacher validateTeacher(Teacher tc);
}

8.1 Write the encapsulation class to establish the connection with the database JDBCUtil.java

package JDBCUtil;


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

    public class JDBCUtil {
         //1.數(shù)據(jù)庫地址  (根據(jù)不同的數(shù)據(jù)標準是不一樣)
          private  final  static String DBURL = "jdbc:mysql://localhost:3306/student_crm?useUnicode=true&characterEncoding=UTF8";
          //2.設(shè)置用戶和密碼
          private  final  static String  USERNAME = "root";
          private  final  static String  PASSWORD = "root";
          //3.設(shè)置驅(qū)動名稱 (根據(jù)不同的數(shù)據(jù)標準是不一樣)
          private  final  static String  DBDRIVER = "com.mysql.jdbc.Driver";
          /**
           * 獲取數(shù)據(jù)庫連接
           * @return  返回數(shù)據(jù)庫連接
           */
          public  static  Connection  getConnection(){
              Connection  con = null;
              try {
                Class.forName(DBDRIVER);
                con  =  DriverManager.getConnection(DBURL, USERNAME, PASSWORD);
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
              return  con;    
          }
//關(guān)閉連接 
          public static void  closeJDBC(Statement st,Connection  con) throws SQLException{
                if(st!=null){
                    st.close();
                }
                if(con!=null){
                    con.close();
                }
          }

}

8.2 Implementation of the dao layer

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.zr.dao.TeacherDao;
import com.zr.model.Teacher;
import JDBCUtil.JDBCUtil;
public class TeacherDaoImpl implements TeacherDao{
    /**
     * 輸入老師的對象,返回老師對象
     * @param args
     */
    public Teacher validateTeacher(Teacher tc) {
        Teacher teacher=new Teacher();
        //sql語句
        StringBuffer sql=new StringBuffer("select * from teacher where tname=? and tpsw=?");
        //獲取數(shù)據(jù)庫連接
        Connection con=JDBCUtil.getConnection();
        try {
            PreparedStatement  pst=con.prepareStatement(sql.toString());
            pst.setString(1, tc.getTname());
            pst.setString(2, tc.getTpsw());
            //返回一個結(jié)果集
            ResultSet rs=pst.executeQuery();
            if (rs.next()) {
            //把結(jié)果集里面的數(shù)據(jù)放入對應(yīng)的teacher對象
                teacher=new Teacher(rs.getInt("tid"),rs.getString("tname"),rs.getString("tpsw"));
            } 
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return teacher;
    }
}

9 Service Layer

public interface valiDateService {
/**
 * @param tc
 * @return 老師對象
 * 根據(jù)用戶輸入值驗證老師是否存在
 */
    public Teacher valiDateTeacher(Teacher tc);

}

10 Service layer implements ServiceImpl.java

import com.zr.dao.TeacherDao;
import com.zr.daoIm.TeacherDaoImpl;
import com.zr.model.Teacher;
import com.zr.service.valiDateService;
public class valiDateServiceImpl implements valiDateService{
    public Teacher valiDateTeacher(Teacher tc) {
        //父類的引用指向子類的對象,父類可以直接調(diào)用子類的方法
        TeacherDao teacherDao=new TeacherDaoImpl();
        //調(diào)用dao層的方法驗證存在
        Teacher teacher=teacherDao.validateTeacher(tc);
        return teacher;
    }
}

11 com.zr.controller layer

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.zr.model.Teacher;
import com.zr.service.valiDateService;
import com.zr.serviceIm.valiDateServiceImpl;
public class LoginController extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 獲取前臺form表單的input輸入框
        String tname = req.getParameter("tname");
        String tpsw = req.getParameter("tpsw");
        // 將前臺對象放入tc對象,作為輸入?yún)?shù)
        Teacher tc = new Teacher();
        tc.setTname(tname);
        tc.setTpsw(tpsw);
        // 調(diào)用Service層的方法傳入tc對象,并用t接收返回結(jié)果
        valiDateService vds = new valiDateServiceImpl();
        Teacher t = vds.valiDateTeacher(tc);
        // 獲取JSP作用域session,將老師t對象放入session
        HttpSession session = req.getSession();
        int a = t.getTid();//最好根據(jù)返回的老師的id進行判斷
        if (a != 0) {
            // 返回的有id,重定向到登錄成功界面
            req.getRequestDispatcher("main.jsp").forward(req, resp);
            session.setAttribute("teacher", t);
        } else {
            // 返回空值,請求轉(zhuǎn)發(fā)到登錄界面
            req.getRequestDispatcher("login.jsp").forward(req, resp);
        }
    }
}