动手动脑——登录界面

1． 关于网站系统开发的技术：

（1）技术内容：

HTML语法、CSS语法、JavaScript语法

（2）后台编程：

数据库：SQLServer设计、MySQL设计、Access设计、Oracle设计

另外，Java语言（Java database Connectivity（JjavawebDbc）技术、Servlet技术、jsp(Java Server Pages)技术，JavaBean(Application)应用组件技术）、面向对象分析设计思想、设计模式和框架结构、XML语言、网页脚本语言、开发工具（数据库、web服务器、集成开发环境（IDE））。

2. 源程序代码：

 （1）创建一个接口

package com.jaovo.msg.dao;

import java.util.List;

import com.jaovo.msg.model.User;


public interface IUserDao {
    public void add(User user);
    public void delete(int id);
    public void update(User user);
    public User load(int id);
    public User load(String username);
    public List<User> load();
    
}

（2）创建一个类实现IUserDao接口

package com.jaovo.msg.dao;

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


import com.jaovo.msg.Util.DBUtil;
import com.jaovo.msg.Util.UserException;
import com.jaovo.msg.model.User;

import sun.net.www.content.text.plain;

public class UserDaoImpl implements IUserDao {

    @Override
    public void add(User user) {
        //获得链接对象
        Connection connection = DBUtil.getConnection();
        //准备sql语句
        String sql = "select count(*) from t_user where username = ?";
        //创建语句传输对象
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        try {
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, user.getUsername());
            //接收结果集
            resultSet = preparedStatement.executeQuery();
            //遍历结果集
            while(resultSet.next()) {
                if (resultSet.getInt(1) > 0) {
                    throw new UserException("用户已存在") ;
                }
            }
            
            sql = "insert into t_user(username,password) value (?,?)";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, user.getUsername());
            preparedStatement.setString(2, user.getPassword());
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            //关闭资源
            DBUtil.close(resultSet);
            DBUtil.close(preparedStatement);
            DBUtil.close(connection);
        }
        
    }

    @Override
    public void delete(int id) {
        Connection connection = DBUtil.getConnection();
        String sql = "delete from t_user where id = ?";
        PreparedStatement preparedStatement = null;
        
        try {
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, id);
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            DBUtil.close(preparedStatement);
            DBUtil.close(connection);
        }
        
    }

    @Override
    public void update(User user) {
        Connection connection = DBUtil.getConnection();
        //准备sql语句
        String sql = "update t_user set password = ? , where id = ?";
        //创建语句传输对象
        PreparedStatement preparedStatement = null;
        try {
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, user.getPassword());
            preparedStatement.setInt(2, user.getId());
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            DBUtil.close(preparedStatement);
            DBUtil.close(connection);
        }
    }

    @Override
    public User load(int id) {
        Connection connection = DBUtil.getConnection();
        //准备sql语句
        String sql = "select * from t_user  where id = ?";
        //创建语句传输对象
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        User user = null;
        try {
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, id);
            resultSet = preparedStatement.executeQuery();
            while(resultSet.next()) {
                user = new User();
                user.setId(id);
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            DBUtil.close(resultSet);
            DBUtil.close(preparedStatement);
            DBUtil.close(connection);
        }
        return  user;
    }

    @Override
    public User load(String username) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public List<User> load() {
        Connection connection = DBUtil.getConnection();
        //准备sql语句
        String sql = "select * from t_user ";
        //创建语句传输对象
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        //集合中只能放入user对象
        List<User> users = new ArrayList<User>();
        User user = null;
        try {
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while(resultSet.next()) {
                user = new User();
                user.setId(resultSet.getInt("id"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                users.add(user);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            DBUtil.close(resultSet);
            DBUtil.close(preparedStatement);
            DBUtil.close(connection);
        }
        return  users;
    }

}

（3）创建一个com.jaovo.msg.model包，写一个User类

package com.jaovo.msg.model;

public class User{
    
    private int id;
    private String  username;
    private String  password;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
}

（4）创建一个com.jaovo.msg.Util包：

添加DBUtil类：

package com.jaovo.msg.Util;
//
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBUtil {
    
    public  static  Connection getConnection() {
        try {
            //1 加载驱动
            Class.forName("com.mysql.jdbc.Driver").newInstance();
        } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String user = "root";
        String password = "123456";
        String url = "jdbc:mysql://localhost:3306/jaovo_msg";
        Connection connection = null;
        try {
            //2 创建链接对象connection
             connection = DriverManager.getConnection(url,user,password);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return connection;
    }
    
    //关闭资源的方法
    public static void close(Connection connection ) {
        try {
            if (connection != null) {
                connection.close();
            }
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void close(PreparedStatement preparedStatement ) {
        try {
            if (preparedStatement != null) {
                preparedStatement.close();
            }
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void close(ResultSet resultSet ) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    
}

添加UserException类

package com.jaovo.msg.Util;

public class UserException extends RuntimeException{

    public UserException() {
        super();
        // TODO Auto-generated constructor stub
    }

    public UserException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
        // TODO Auto-generated constructor stub
    }

    public UserException(String message, Throwable cause) {
        super(message, cause);
        // TODO Auto-generated constructor stub
    }

    public UserException(String message) {
        super(message);
        // TODO Auto-generated constructor stub
    }

    public UserException(Throwable cause) {
        super(cause);
        // TODO Auto-generated constructor stub
    }
    
}

（5）创建一个SQL文件夹，放入init.sql

-- mysal -u root -p root;
-- show databases;
-- drop database jaovo_shop;

create database jaovo_msg;
use jaovo_msg;
GRANT ALL ON jaovo_msg.* to "jaovo"@"localhost" IDENTIFIED BY "root";
create table t_user(
     id int(10) primary key auto_increment,
     username varchar(255),
     password varchar(255),
     nickname varchar(255),
     type int(2),
     status int(2)
);

create table t_message(
   id          int(10) primary key auto_increment,                
   title                varchar(254),
   content              text,
   post_date             datetime,
   user_id               int(10),
   CONSTRAINT FOREIGN KEY(user_id) REFERENCES t_user(id)
);

create table t_comment(
   id        int(10) primary key auto_increment,  
   content       text,
   post_date     datetime,
   user_id       int(10),
   msg_id        int(10),
   CONSTRAINT FOREIGN KEY(user_id) REFERENCES t_user(id),
   CONSTRAINT FOREIGN KEY(msg_id) REFERENCES t_message(id)
);

（6）在WebContent---->META-INF---->创建user文件夹----->分别创建三个jsp文件

add.jsp：

<%@page import="com.jaovo.msg.Util.UserException"%>
<%@page import="com.jaovo.msg.dao.UserDaoImpl"%>
<%@page import="com.jaovo.msg.model.User"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<%
    //接收客户端传递过来的参数
    String username = request.getParameter("username");
    String password = request.getParameter("password");
    if(username == null || "".equals(username.trim())){
        request.setAttribute("error", "用户名不能为空");
    
%>
    <jsp:forward page="addInput.jsp"></jsp:forward>
<%
    }
    User user = new User();
    user.setUsername(username);
    user.setPassword(password);
    UserDaoImpl userDao = new UserDaoImpl();
    try{
        
    userDao.add(user);
    //重定向
    response.sendRedirect("list.jsp");
%>

    
    
<%
    }catch(UserException e){
%>
    <h2 style="color:red ; font-size:50px">发生错误 : <%=e.getMessage() %></h2>
    <%
    }
    %>
</html>

addInput.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <title>用户添加页面</title>
</head>
<body>
    <%=request.getAttribute("error") %>
    <form action="add.jsp" method="get">
        <table align="center" border="1" width="500">
            <tr>
                <td>用户名称 : </td>
                <td>
                    <input type="text" name="username" />
                </td>
            </tr>
                <tr>
                <td>用户密码:</td>
                <td>
                    <input type="password" name="password" />
                </td>
            </tr>
            <tr align="center">
                <td colspan="2">
                    <input type="submit" value="提交" />
                    <input type="reset" value="重置" />
                </td>
            </tr>
        </table>
    </form>
</body>
</html>

list.jsp：

<%@page import="com.jaovo.msg.model.User"%>
<%@page import="java.util.List"%>
<%@page import="com.jaovo.msg.dao.UserDaoImpl"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户展示界面</title>
</head>
<%
    UserDaoImpl userDao = new UserDaoImpl();
    List<User> users = userDao.load();
%>
<body>
    <table align="center" border="1" width="500">
        <tr>
            <td>用户编号</td>
            <td>用户名称</td>
            <td>用户密码</td>
        </tr>
        <%
            for( User user : users ){
        %>
        <tr>
            <td> <%=user.getId() %></td>
            <td> <%=user.getUsername() %></td>
            <td> <%=user.getPassword() %></td>
            <td> <a href="delete.jsp ? id="<%=user.getId() %>" >删除</a></td>
            
        </tr>
        <%
            }
        %>
    </table>
</body>
</html>

（7）其中，在WebContent---->WEB-INF---->lib文件夹中加载两个包：

jstl-1.2.jar
mysql-connector-java-5.1.38-bin.jar

3.运行结果截图：

 

创建后显示当前用户列表

 

 

若输入同名用户，则会显示已存在。不可创建

4.关于软件工程概论课程的希望、目标以及未来规划：

（1）希望及目标：

通过本课程了解软件工程的历史背景、现目前发展以及未来职业方向，培养学习软件工程专业的兴趣。

（2）未来规划：

通过专业学习，提升专业技能，立志成为一个不拖后腿的程序媛。