JavaWeb学习笔记（三）：使用druid连接池简易登录实例

电玩女神 2022-09-11 07:29 21阅读 0赞

*  druid是一个非常常用的数据库连接池，可以和jdbc template一起来使用
 *  下面我们就模拟一个登录的场景

# 数据库建设 #

*  创建一个login数据库，并且创建一个user表包含id，username，password三个字段。
 *  并且默认一个数据，做好数据准备工作  
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# 项目搭建 #

*  在IDEA中创建一个login模块，并在src目录中创建我们要用到的包  
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 *  在包domain存放我们的用户类User对应数据库user表，设置成员变量一一对应user数据库表

package cn.wang.domain;
    
    public class User { 
        private int id;
        private String username;
        private String password;
    
        @Override
        public String toString() { 
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", password='" + 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;
        }
    }

*  数据库连接池配置，在web文件夹下新建WEB-INF文件夹，把需要的jar包放到lib文件夹下，并加载到模块中  
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 *  在src文件夹下存放druid配置文件 druid.properties文件，配置数据库信息

driverClassName=com.mysql.jdbc.Driver
    url=jdbc:mysql:///login
    username=root
    password=
    initialSize=5
    maxActive=10
    maxWait=3000

*  在util包中新建JDBCUtils数据库连接工具类

package cn.wang.util;
    
    import com.alibaba.druid.pool.DruidDataSourceFactory;
    
    import javax.sql.DataSource;
    import java.io.IOException;
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.SQLException;
    import java.util.Properties;
    
    /** * Durid连接池使用 */
    public class JDBCUtils { 
        private static DataSource ds;
    
        static { 
            try { 
                Properties pro = new Properties();
                InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
                pro.load(is);
                 ds = DruidDataSourceFactory.createDataSource(pro);
            } catch (IOException e) { 
                e.printStackTrace();
            } catch (Exception e) { 
                e.printStackTrace();
            }
        }
    
        /** * 获取连接池对象 */
        public static DataSource getDataSource() { 
            return ds;
        }
    
        /** * 获取连接对象 */
        public static Connection getConnection() throws SQLException { 
            return ds.getConnection();
        }
    
    }

*  在包dao中新建UserDao对数据库进行操作，返回User对象

package cn.wang.dao;
    
    import cn.wang.domain.User;
    import cn.wang.util.JDBCUtils;
    import org.springframework.dao.DataAccessException;
    import org.springframework.jdbc.core.BeanPropertyRowMapper;
    import org.springframework.jdbc.core.JdbcTemplate;
    
    public class UserDao { 
        private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
    
        public User login(User loginUser) { 
            try { 
                String sql = "select * from user where username = ? and password = ?";
                User user = template.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class), loginUser.getUsername(), loginUser.getPassword());
    
                return user;
            } catch (DataAccessException e) { 
                e.printStackTrace();
                return null;
            }
        }
    }

*  创建Test测试数据连接是否正确，在包test中创建UserDaoTest，并且进行执行，执行成功则我们的连接正常

package cn.wang.test;
    
    import cn.wang.dao.UserDao;
    import cn.wang.domain.User;
    import org.junit.Test;
    
    
    
    public class UserDaoTest { 
        @Test
        public void testLogin() { 
            User loginuser = new User();
            loginuser.setUsername("admin");
            loginuser.setPassword("123456");
    
    
            UserDao dao = new UserDao();
            User user = dao.login(loginuser);
    
            System.out.println(user);
        }
    }

*  上面我们的内部处理已经完成，后面我们只需要将，web提交的数据进行上面流程并且进行登录判断，在新建servlet进行数据接受并调用上述的过程
 *  在web目录下新建login.html文件，用于数据提交

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <form action="/loginServlet" method="post">
            用户名:<input type="text" name="username"> <br>
            密码:<input type="password" name="password"><br>
    
            <input type="submit" value="登录">
    
        </form>
    </body>
    </html>

*  在servlet包中创建LoginServlet用于接受表单数据

package cn.wang.web.servlet;
    
    import cn.wang.dao.UserDao;
    import cn.wang.domain.User;
    
    
    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 java.io.IOException;
    
    @WebServlet("/loginServlet")
    public class LoginServlet extends HttpServlet { 
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            this.doGet(request, response);
    
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            request.setCharacterEncoding("utf-8");
            System.out.println("doget");
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            User loginUser = new User();
            loginUser.setUsername(username);
            loginUser.setPassword(password);
            UserDao dao = new UserDao();
            User user = dao.login(loginUser);
            if (user == null) { 
                request.getRequestDispatcher("/failServlet").forward(request, response);
            } else { 
                request.setAttribute("user", user);
                request.getRequestDispatcher("/successServlet").forward(request, response);
            }
        }
    }

*  接收到表单的数据，执行dao中的逻辑，并在servlet中进行结果判断，有结果转到成功servlet处理，失败则转到另一个进行处理
 *  失败

package cn.wang.web.servlet;
    
    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 java.io.IOException;
    
    @WebServlet("/failServlet")
    public class FailServlet extends HttpServlet { 
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("登录失败，用户名或密码错误");
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            this.doPost(request, response);
        }
    }

*  成功

package cn.wang.web.servlet;
    
    import cn.wang.domain.User;
    
    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 java.io.IOException;
    
    @WebServlet("/successServlet")
    public class SuccessServlet extends HttpServlet { 
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            User user = (User) request.getAttribute("user");
            if (user != null) { 
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("登陆成功！"+user.getUsername()+",欢迎你");
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            this.doPost(request,response);
        }
    }

![在这里插入图片描述][e9f5c898c4b6439cbaaea0587a3852ba.png]  
![在这里插入图片描述][a64faea8162949839140a7be1411a42d.png]  
![在这里插入图片描述][6e5bd85a79a643d7aefda62d3c1b5720.png]  
[代码地址][Link 1]

[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5rih55uu5oiQ5Lmm_size_14_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/123232200c9a45c58a1ba4a30046cd44.png
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[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5rih55uu5oiQ5Lmm_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/0352e731a04d440086f132477accaadc.png
[e9f5c898c4b6439cbaaea0587a3852ba.png]: /images/20220828/b4f35e3bf1664763bda2273b6c53f7a0.png
[a64faea8162949839140a7be1411a42d.png]: /images/20220828/9311b6dcc0c64d7a9bdafe46442d35ca.png
[6e5bd85a79a643d7aefda62d3c1b5720.png]: /images/20220828/8fd05baafac44229abfbe8c0819e375a.png
[Link 1]: https://github.com/superkingM/cainiaojava/tree/main/login