servlet连接数据库输出数据库中的数据

xml文件配置

<servlet> <!--名字随便取-->
    <servlet-name>TwoSaervlet</servlet-name>
    <!--是servelt的全类名  主要作用做反射-->
    <servlet-class>serverlet.TwoSaervlet</servlet-class>
</servlet>
<servlet-mapping><!--与上面名字一样-->
    <servlet-name>TwoSaervlet</servlet-name>
    <!--想烦你问servlet的路径 以/开头-->
    <url-pattern>/two</url-pattern>
</servlet-mapping>

 

 

/*jdbc 链接
1 加载驱动
2 创建连接对象
3 编写sql
4 执行sql
5 处理结果
6 关闭资源
* */
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        //1 加载驱动
        Connection conn=null;
        PreparedStatement pre = null;
        ResultSet rs = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            //2 创建连接对象
            String url = "jdbc:mysql://localhost:3306/javaweb";
            String name = "root";
            String password = "123456";
            conn = DriverManager.getConnection(url, name, password);
            //3 编写sql 写项目不能用*
            String sql = "select * from user";
            //4 执行sql
         pre = conn.prepareStatement(sql);
            // 5 获取结果 处理结果
            rs = pre.executeQuery();

            while(rs.next()){
                servletResponse.setContentType("text/html;;charset=utf-8");
                PrintWriter out = servletResponse.getWriter();
                out.write(rs.getString("id"));
                out.write(rs.getString("username"));
                out.write(rs.getString("password"));
                out.write(rs.getString("dept"));
                out.write(rs.getString("sex"));
            }



        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //6、关闭流资源
            if (rs != null){
                try {
                    rs.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if (pre != null){
                try {
                    pre.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if (conn != null){
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }

        }
        

    }