1 创建项目

1.1 创建一个空项目

1.2 新增模块

1.3 让模块支持webapp标准

2 编辑程序

2.1 编写StudentServlet类

package cc.linuxcc.servlet;

import jakarta.servlet.*;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;

public class StudentServlet implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    @Override
    public void service(ServletRequest request, ServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        // JDBC
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            // 注册驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 获取连接
            String url = "jdbc:mysql://localhost:3306/linuxcc";
            String user = "root";
            String password = "root";
            conn = DriverManager.getConnection(url, user, password);

            // 获取预编译的数据库操作对象
            String sql = "select username,password from user";
            ps = conn.prepareStatement(sql);
            // 执行SQL
            rs = ps.executeQuery();
            while (rs.next()) {
                String username = rs.getString("username");
                String passwd = rs.getString("password");

                // 输出
                out.print(username + ": " + passwd);
            }
            // 处理结果集


        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            // 释放资源
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }

            if (ps != null) {
                try {
                    ps.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }

            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }

    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

2.2 添加Servlet映射

    <servlet>
        <servlet-name>StudentServlet</servlet-name>
        <servlet-class>cc.linuxcc.servlet.StudentServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>StudentServlet</servlet-name>
        <url-pattern>/get/student/</url-pattern>
    </servlet-mapping>