用Servlet--jsp--jdbc模拟用户注册

环境配置：
在进行项目之前首先呢需要配置我们所需要的各种环境（jdk,Mysql,Tomcat,Maven,jdbc）;
下面是我们Tomcat相关配置，如图：

Tomcat.png

Mysql相关表，为了方便我们只设置了用户姓名和密码

create table user(
    username varchar(20) not null,
    `password` varchar(20) not null
);

Login.jsp
将表单的数据提交给hello-servlet

<%@ page contentType="text/html;charset=UTF-8" language="java" %>



    姓名：

    密码：

    提交：

User.java 用户类

   private String username;
    private String password;

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

    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{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

JDBCUtil.java
为了项目开发方便，提前将JDBC封装成一个jdbc工具类：

public class JDBCUtil {
    private Connection conn = null;
    private PreparedStatement ps = null;
    private static String username = "root";
    private static String password = "root123";
    private static String driver = "com.mysql.jdbc.Driver";
    private static String url = "jdbc:mysql:///jdbc";
    public JDBCUtil() {
    }

    static {
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    public  Connection getConnection(){
        Connection conn = null;
        try {
            conn = DriverManager.getConnection(url,username,password);

        } catch (SQLException e) {
             e.printStackTrace();
        }
        return conn;
    }
    public PreparedStatement ps(String sql){
        PreparedStatement ps = null;
        Connection conn = getConnection();
        try {
            ps = conn.prepareStatement(sql);
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return ps;
    }
    public  void Close(){
        if (ps != null) {
            try {
                ps.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
    private void Close(ResultSet rs){
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        Close();
    }
}

HelloServlet.java
在用户进行表单输入之后，将表单数据传给Servlet进行处理：

//添加注解
@WebServlet(name = "helloServlet", value = "/hello-servlet")
public class HelloServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        UserDao dao = new UserDao();
        User user = null;
        int result = 0;
        PrintWriter out = null;
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        user = new User(username, password);
        result = dao.add(user);
        out = response.getWriter();
        if (result !=0){
            out.print("注册成功");
        }else {
            out.print("注册失败");
        }
    }
}

UserDao.java
拿到表单数据之后用UserDao类进行对数据库的添加操作：

public class UserDao {
    private JDBCUtil jdbcUtil = new JDBCUtil();
    public int add(User user) {
        String sql = "insert into user values(?,?)";
        PreparedStatement ps = jdbcUtil.ps(sql);
        int result = 0;
        try {
            ps.setString(1, user.getUsername());
            ps.setString(2, user.getPassword());
            result = ps.executeUpdate();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return result;
    }
}

启动Tomcat，访问Login.jsp，在表单中输入姓名：张三 ，密码：123；

Snipaste_2021-09-15_21-51-53.png

此时界面上输出了注册成功：

Snipaste_2021-09-15_21-54-26.png

我们进入到数据库查看结果：

Snipaste_2021-09-15_21-56-23.png

注册成功！