摘要：顯示層控制層數(shù)據(jù)層統(tǒng)一交給或者處理處理流程客戶端發(fā)送到執(zhí)行讀取返回返回給在返回給在給客戶端問(wèn)題代碼雜亂即方式客戶端發(fā)送到然后執(zhí)行用于讀取控制器獲取到讀取的數(shù)據(jù)以后再次返回給生成文件給客戶端分為顯示層控制層模型層屬于提供的分布式組件服務(wù)分

顯示層,控制層,數(shù)據(jù)層,統(tǒng)一交給jsp或者javabean處理.

客戶端發(fā)送request 到 jsp jsp 執(zhí)行javabean javabean讀取databases

返回 databases 返回給javabean 在返回給jsp 在response 給客戶端

代碼雜亂
即 jsp + dao 方式

客戶端發(fā)送request 到servlet 然后servlet 執(zhí)行javabean javabean用于讀取databases 控制器,獲取到j(luò)avabean讀取的數(shù)據(jù)以后,再次返回給jsp,jso生成html文件,response 給客戶端
分為 顯示層 控制層 模型層

EJB 屬于SUN提供的分布式組件服務(wù) 分為會(huì)話bean 實(shí)體bean 消息驅(qū)動(dòng)bean

一個(gè)登錄程序
用戶提交登錄信息,發(fā)送給servlet servlet數(shù)據(jù)驗(yàn)證失敗將會(huì)返回給登錄頁(yè),同時(shí)servlet將會(huì)調(diào)用數(shù)據(jù)層操作dao,dao到數(shù)據(jù)庫(kù)databases進(jìn)行驗(yàn)證,結(jié)果返回給servlet 然后返回兩個(gè)結(jié)果,登錄成功,登錄失敗.

![](https://melovemingming-125387...
)

package com.ming.dbc;

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

public class DatabaseConnection {
    private static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
    private static final String DBURL = "jdbc:mysql://47.94.95.84:32786/test";
    private static final String DBUSER = "test";
    private static final String DBPASSWORD = "ABCcba20170607";
    private Connection connection = null;
    // 連接數(shù)據(jù)庫(kù)
    public DatabaseConnection() throws Exception{
        try{
            Class.forName(DBDRIVER);
            connection = DriverManager.getConnection(DBURL, DBUSER, DBPASSWORD);
        }catch (Exception e){
            throw e;
        }
    }
    // 獲得數(shù)據(jù)庫(kù)連接
    public Connection getConnection(){
        return this.connection;
    }
    // 數(shù)據(jù)庫(kù)關(guān)閉
    public void close() throws Exception{
        if(this.connection != null){
            try{
                this.connection.close();
            }catch (Exception e){
                throw  e;
            }
        }
    }
}

package com.ming.dao;

import com.ming.vo.User;

public interface IUserDAO {
    /**
     * 用戶登錄驗(yàn)證
     * @param user 傳入VO對(duì)象
     * @return 驗(yàn)證操作結(jié)果
     * @throws Exception 拋出錯(cuò)誤
     */
    public boolean findLogin(User user) throws Exception;
}

package com.ming.dao;

import com.ming.vo.User;

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

public class UserDAOImpl implements IUserDAO {
    // 數(shù)據(jù)庫(kù)連接對(duì)象
    private Connection connection = null;
    // 操作對(duì)象
    private PreparedStatement preparedStatement = null;
    // 數(shù)據(jù)庫(kù)連接
    public UserDAOImpl(Connection _connection){
        this.connection = _connection;
    }
    /**
     * 用戶登錄驗(yàn)證
     *
     * @param user 傳入VO對(duì)象
     * @return 驗(yàn)證操作結(jié)果
     * @throws Exception 拋出錯(cuò)誤
     */
    @Override
    public boolean findLogin(User user) throws Exception {
        boolean flag = false;
        try{
            String sql = "SELECT name FROM user WHERE userid = ? AND password = ?";
            // 獲得實(shí)例化對(duì)象
            this.preparedStatement = this.connection.prepareStatement(sql);
            // 設(shè)置id
            this.preparedStatement.setString(1, user.getUserid());
            this.preparedStatement.setString(2, user.getPassword());
            ResultSet resultset = this.preparedStatement.executeQuery();
            if(resultset.next()){
                user.setName(resultset.getString(1));
                flag = true;
            }
        }catch (Exception e){
            throw  e;
        }finally {
            if(this.preparedStatement != null){
                try{
                    this.preparedStatement.close();
                }catch (Exception e){
                    throw  e;
                }
            }
        }
        return flag;
    }
}

package com.ming.dao;

import com.ming.dbc.DatabaseConnection;
import com.ming.vo.User;

public class UserDAOProxy implements IUserDAO {
    private DatabaseConnection databaseConnection = null;
    private IUserDAO dao = null;
    public UserDAOProxy(){
        try{
            this.databaseConnection = new DatabaseConnection();
        }catch (Exception e){
            e.printStackTrace();
        }
        this.dao = new UserDAOImpl(this.databaseConnection.getConnection());
    }
    /**
     * 用戶登錄驗(yàn)證
     *
     * @param user 傳入VO對(duì)象
     * @return 驗(yàn)證操作結(jié)果
     * @throws Exception 拋出錯(cuò)誤
     */
    @Override
    public boolean findLogin(User user) throws Exception {
        boolean flag = false;
        try{
            flag = this.dao.findLogin(user);
        }catch (Exception e){
            throw  e;
        }finally {
            this.databaseConnection.close();
        }
        return flag;
    }
}

package com.ming.factory;

import com.ming.dao.IUserDAO;
import com.ming.dao.UserDAOProxy;

public class DAOFactory {
    public static IUserDAO getIuserDAOInstance(){
        return new UserDAOProxy();
    }
}

package com.ming.vo;

// 對(duì)user表進(jìn)行映射
public class User {
    private String userid;
    private String name;
    private String password;

    public String getUserid() {
        return userid;
    }

    public String getName() {
        return name;
    }

    public String getPassword() {
        return password;
    }

    public void setUserid(String userid) {
        this.userid = userid;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

<%@ page import="java.util.List" %>
<%@ page import="java.util.Iterator" %><%--
  Created by IntelliJ IDEA.
  User: ming
  Date: 19-3-16
  Time: 下午11:07
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    


用戶登錄程序
<%
    List info = (List)request.getAttribute("info");
    if(info != null){
        Iterator iterator = info.iterator();
        while(iterator.hasNext()){
            %>
                
<%=iterator.next()%>
            <%
        }
    }
%>

    用戶id 
    密碼 
    
    

  Archetype Created Web Application
    
        login
        com.ming.servlrt.LoginServlet
    
    
        login
        /loginServlet
    

表單提交到servlet,servlet調(diào)用dao進(jìn)行表單驗(yàn)證,然后dao連接數(shù)據(jù)庫(kù)進(jìn)行驗(yàn)證,驗(yàn)證結(jié)果返回給業(yè)務(wù)層,即servlet,在業(yè)務(wù)層servlet中獲取info等日志信息,然后服務(wù)器端跳轉(zhuǎn)到運(yùn)行結(jié)果頁(yè)面即view層.