实习第一天-----配置环境idea+mysql+jdk以及简单的jdbc项目书写

第一周实习是基于ssm的用户管理系统的编写。

第一天是有关安装环境

第二天搭建ssm项目

 

1.JDBC是什么?（复习）

1）加载驱动；2）创建连接；3）写sql;4)statement对象；5）执行sql得到的结果；6）处理结果集；7）关闭资源
 

2.环境配置 jdk1.8+mysql+idea

1)win+r打开cmd,输入Java -version查看Java版本

如果版本不一样更新一下版本

2)mysql安装，网上教程很多，此处因为有老师发的免安装，我们可直接采用老师的；

安装SQLyog连接数据库

3）idea，**版

3.创建Java-webapp项目

1）创建文件结构如下：

2）打开SQLyog,配置如下

3）创建数据库：

4）注意此处需要导入包，不然不能正常运行

4具体实现代码如下

1）bean.User//实体类 与数据库对接 构造方法 属性 getset tostring

public class User {

public User() {

    }

    public User(int id,String username,String password){
        this.id = id;
        this.username = username;
        this.password = password;
    }
    private int id;
    private String username;
    private String password;

    //不能直接对私有对象进行操作
    //法1 get set
    //法2 构造方法
    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;
    }
    @Override
    public String toString(){
        return "User(" +
                "id="+id+
                ", username='"+username+'\''+
                ", password='"+password+'\''+
                '}';
    }

}

2)dao-userDao  //持久层 对数据库操作 crud

public class UserDao {//数据库的增删改查

    //查询所有的用户
    public List<User> findAll() throws SQLException, ClassNotFoundException {

        List<User> userList = new ArrayList<>();//新建集合
        Connection connection = DBUtil.getConnection();
        System.out.println("获得连接成功");
        //查询
        String sql = "select * from tb_user";

        PreparedStatement statement = connection.prepareStatement(sql);
        ResultSet resultSet = statement.executeQuery();
        while(resultSet.next()){
            User user = new User();
            int id = resultSet.getInt(1);
            String username = resultSet.getString(2);
            String password = resultSet.getString(3);
            user.setId(id);
            user.setUsername(username);
            user.setPassword(password);
            //System.out.println(id+"---"+username+"---"+password);
            userList.add(user);//将数据传入
            //System.out.println(user);

        }

       DBUtil.close(resultSet,statement,connection);
       return userList;
    }
    //根据id删除
    public void deleteById(int id) throws SQLException, ClassNotFoundException {

        //连接数据库
        Connection connection = DBUtil.getConnection();
        System.out.println("");
        String sql = "delete from tb_user where id=?";
        PreparedStatement statement =connection.prepareStatement(sql);
        statement.setInt(1,id);
        statement.executeUpdate();
        DBUtil.close(null,statement,connection);
    }

    public int login(String username,String password) throws SQLException, ClassNotFoundException {

        Connection connection = DBUtil.getConnection();
        Statement state =null;
        ResultSet rs = null;
        int flag=0;
        try
        {
            String sql = "select * from user where username = '"+username+"'";

            state = connection.createStatement();
            rs=state.executeQuery(sql);
            if(rs.next())
            {
                if(rs.getString("password").equals(password))
                {
                    flag=1;
                }
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
            DBUtil.close(rs, state, connection);
        return flag;
    }

    public User findUserByName(String username) throws SQLException, ClassNotFoundException {
        Connection connection = DBUtil.getConnection();
        System.out.println("获得连接成功");


            //Connection connection = DBUtil.getConnection();
            System.out.println("获得连接成功");
            String sql = "select * from tb_user where username=?";
            PreparedStatement statement  =connection.prepareStatement(sql);
            statement.setString(1,username);
            ResultSet resultSet = statement.executeQuery();
            User user=null;
            while(resultSet.next()){
                user=new User();
                int id=resultSet.getInt(1);
                String username1 = resultSet.getString(2);
                String password = resultSet.getString(3);
                user.setId(id);
                user.setUsername(username);
                user.setPassword(resultSet.getString(password));
            }
        DBUtil.close(resultSet,statement,connection);
        return user;

        }

3）service-UserService //业务层 处理i请求

public class UserService {

    public boolean login(String username,String password)  {
        UserDao userDao = new UserDao();
        User user = null;
        try{
            user = userDao.findUserByName(username);
        }catch(SQLException throwables){
            throwables.printStackTrace();
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }
        if(user!=null&&user.getPassword().equals(password)){
            return true;
        }else{
            return false;
        }

    }
}

4）a..servlet-LoginServlet  //控制层 不能直接调用dao 只能调用service

public class LoginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String username = req.getParameter("username");
        String password = req.getParameter("password");
        UserService userService = new UserService();

        Boolean flag = userService.login(username,password);

        if(flag){
            resp.getWriter().write("ok");
            //req.getRequestDispatcher("/index.jsp").forward(req,resp);
        }else {
            resp.getWriter().write("failure");

        }

    }
}

4）b..UserServlet

public class UserServlet extends HttpServlet {
    protected void service(HttpServletRequest req,HttpServletResponse resp)throws ServletException,IOException
    {
        req.setCharacterEncoding("utf-8");//设置字符集
        String method = req.getParameter("method");//获取jsp界面的method参数来判断执行什么方法
        if(method.equals("login"))
        {
            try {
                login(req,resp);//登录方法
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }
    protected void login(HttpServletRequest req,HttpServletResponse resp) throws ServletException, IOException, SQLException, ClassNotFoundException {
        req.setCharacterEncoding("utf-8");
        String username = req.getParameter("username1");
        String password = req.getParameter("password1");//获取用户名密码
        UserDao userdao = new UserDao();
        int flag = userdao.login(username, password);//执行Userdao里面的login方法判断登录的用户名密码是否正确
        if(flag==1)
        {
            System.out.println("登录成功！");
            resp.sendRedirect(req.getContextPath()+"/loginsuccessful.jsp");//登录成功跳转到主界面
        }
        else
        {
            System.out.println("登录失败！");
            resp.sendRedirect(req.getContextPath()+"/login.jsp");
        }
    }
}

5) util-DBUtil    //数据库的连接与关闭

public class DBUtil {
    //连接数据库
    public static Connection getConnection() throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/whlg","root","123456");
        return connection;
    }

    //关闭数据库
    public static void close(ResultSet resultSet, Statement statement, Connection connection) throws SQLException {
        if(resultSet!=null){
            resultSet.close();
        }
        if(statement!=null){
            statement.close();
        }
        if(connection!=null){
            connection.close();
        }

    }

}

6）web.xml

<servlet>
    <servlet-name>hello</servlet-name>
    <servlet-class>com.servlet.UserServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>hello</servlet-name>
    <url-pattern>/hello</url-pattern>
</servlet-mapping>

<servlet>
    <servlet-name>loginServlet</servlet-name>
    <servlet-class>com.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>loginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
</servlet-mapping>

7)index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>登陆界面</title>
  </head>
  <body>
  <!-- -->
    <h1 style="color:#13b353">登录</h1>
    <from  action="/login" method="post">
      name:<input name="username" type ="text">
      password:<input name="password" type ="password">
      <input type="submit" value="login">
    </from>
  </body>
</html>

8）login.isp

<%@ 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>Insert title here</title>

</head>

<body>

<form action="${pageContext.request.contextPath}/servlet/Userservlet?method=login" method="post">

    <h1>登录 界面</h1>

    <div>

        <input type="text" placeholder="登录名" required="" id="username" name="username1"/>

    </div>

    <div>

        <input type="password" placeholder="密码" required="" id="password" name="password1" />

    </div>

    <div>

        <input type="submit" value="登 录" />

    </div>

</form>

</body>

</html>

9）logincheck.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
    request.setCharacterEncoding("UTF-8");
    UserDao userDao = new UserDao();
    //取数值

    String username1 = (String) request.getParameter("username");
    String password1 = (String) request.getParameter("password");
   // String sql= "select username from tb_user where username="+"'"+username1+"'";//定义一个查询语句
    //String sql1="select password from tb_user where password="+"'"+password1+"'";
     String sql= "select username from tb_user where username=?";//定义一个查询语句
    String sql1="select password from tb_user where password=?";
    Connection connection = DBUtil.getConnection();
    PreparedStatement statement = connection.prepareStatement(sql);
    PreparedStatement statement2 = connection.prepareStatement(sql1);
    ResultSet resultSet = statement.executeQuery();
    ResultSet resultSet1 = statement2.executeQuery();

    if(resultSet.next()&&resultSet1.next()){
        if(password1.equals(resultSet.getObject("password"))){
            System.out.println(" 查询成功！");
            response.sendRedirect("loginsuccessful.jsp");
        }

    }
    else{
        //out.print("<script language='javaScript'>alert('用户名或密码错误');</script>");
        System.out.println("用户名或密码错误");
        response.setHeader("refresh","url=login.jsp");
    }

%>

</body>
</html>

10）loginsuccessful.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>

    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    <title>Insert title here</title>

</head>

<body>

这是主页，你已成功登录！

</body>

</html>

 因为今天之前很久没有接触过Java代码了，所以还是很生疏，有了老师的复习讲解与具体实现，自己也慢慢的熟悉了起来。