From bba36badbf341e8c1f75a3106e9cbb8b30d9a793 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?5=E5=8F=B7=E6=9E=97=E4=BC=9F=E5=BD=AC?= <2401916501@qq.com> Date: Wed, 24 May 2023 00:16:47 +0800 Subject: [PATCH] =?UTF-8?q?=E4=BD=9C=E4=B8=9A?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../20230523 \344\275\234\344\270\232.md" | 159 ++++++++++++++++++ 1 file changed, 159 insertions(+) create mode 100644 "05 \346\236\227\344\274\237\345\275\254/20230523 \344\275\234\344\270\232.md" diff --git "a/05 \346\236\227\344\274\237\345\275\254/20230523 \344\275\234\344\270\232.md" "b/05 \346\236\227\344\274\237\345\275\254/20230523 \344\275\234\344\270\232.md" new file mode 100644 index 0000000..db21f6b --- /dev/null +++ "b/05 \346\236\227\344\274\237\345\275\254/20230523 \344\275\234\344\270\232.md" @@ -0,0 +1,159 @@ + + +```java +// # 作业， +//* 1 数据库相关的操作，使用封装的工具类 +// * 2 编写四个servlet，使用注解指定相关的访问路径，分别对应查询，修改，删除，添加的操作 +//* 3 从浏览器中，访问这中个路径，显示响应的信息，查询显示结果，其它的显示成功或是失败 +// * 4 预习题：如何通过浏览器传送请求参数给servlet，servlet如何接收这些参数，并使用这些参数，去影响数据库的操作？ +//查询 +import jakarta.servlet.ServletException; +import jakarta.servlet.annotation.WebServlet; +import jakarta.servlet.http.HttpServlet; +import jakarta.servlet.http.HttpServletRequest; +import jakarta.servlet.http.HttpServletResponse; +import java.io.IOException; +import java.io.PrintWriter; +import java.sql.*; + +@WebServlet("/text") +public class text extends HttpServlet { + @Override + protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + resp.setContentType("text/html;charset=utf-8"); + resp.setCharacterEncoding("utf-8"); + + try { + Class.forName("com.mysql.jdbc.Driver"); + String url = "jdbc:mysql://localhost:3306/text?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + PreparedStatement pst = conn.prepareStatement("select * from student"); + ResultSet re = pst.executeQuery(); + PrintWriter writer = resp.getWriter(); + writer.write(""); + writer.write(""); + while (re.next()) { + int id = re.getInt(1); + String name = re.getString(2); + String sex = re.getString(3); + writer.write(""); + writer.write(""); + writer.write(""); + } + re.close(); + pst.close(); + conn.close(); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } catch (SQLException e) { + throw new RuntimeException(e); + } + + } + + @Override + protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + super.doPost(req, resp); + } +} +``` + + + +```java +//修改 +import jakarta.servlet.ServletException; +import jakarta.servlet.annotation.WebServlet; +import jakarta.servlet.http.HttpServlet; +import jakarta.servlet.http.HttpServletRequest; +import jakarta.servlet.http.HttpServletResponse; +import java.io.IOException; +import java.sql.*; + +@WebServlet("/text") +public class text extends HttpServlet { + @Override + protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + resp.setContentType("text/html;charset=utf-8"); + resp.setCharacterEncoding("utf-8"); +try { + Class.forName("com.mysql.jdbc.Driver"); + String url = "jdbc:mysql://localhost:3306/text?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + PreparedStatement pst = conn.prepareStatement("update student set name = 'a' where name = 'b'"); + int i = pst.executeUpdate(); + if (i>0){ + resp.getWriter().write("修改了"+i+"行"); + }else { + System.out.println("修改失败"); + } + pst.close(); + conn.close(); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } catch (SQLException e) { + throw new RuntimeException(e); + } + +} + +@Override +protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + super.doPost(req, resp); +} + +} +``` + + +```java + +//删除 +import jakarta.servlet.ServletException; +import jakarta.servlet.annotation.WebServlet; +import jakarta.servlet.http.HttpServlet; +import jakarta.servlet.http.HttpServletRequest; +import jakarta.servlet.http.HttpServletResponse; +import java.io.IOException; +import java.sql.*; + +@WebServlet("/text") +public class text extends HttpServlet { + @Override + protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + resp.setContentType("text/html;charset=utf-8"); + resp.setCharacterEncoding("utf-8"); + + try { + Class.forName("com.mysql.jdbc.Driver"); + String url = "jdbc:mysql://localhost:3306/text?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + PreparedStatement pst = conn.prepareStatement("delete from student where id = 1"); + int i = pst.executeUpdate(); + if (i>0){ + resp.getWriter().write("删除了"+i+"行"); + }else { + System.out.println("删除失败"); + } + pst.close(); + conn.close(); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } catch (SQLException e) { + throw new RuntimeException(e); + } + + } + + @Override + protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + super.doPost(req, resp); + } +} +``` \ No newline at end of file -- Gitee
ID姓名性别
"+id+""+name+""+sex+"