From a4da5a53a23cbdf573dc1b0925e1702a6d948e18 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E8=AE=B8=E6=81=A9=E6=B0=91?= <3256972080@qq.com> Date: Tue, 23 May 2023 23:01:07 +0800 Subject: [PATCH] =?UTF-8?q?jdbc=E7=AC=AC=E4=B8=89=E6=AC=A1=E4=BD=9C?= =?UTF-8?q?=E4=B8=9A?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...11\346\254\241\344\275\234\344\270\232.md" | 204 ++++++++++++++++++ ...14\346\254\241\344\275\234\344\270\232.md" | 2 +- 2 files changed, 205 insertions(+), 1 deletion(-) create mode 100644 "30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\270\211\346\254\241\344\275\234\344\270\232.md" diff --git "a/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\270\211\346\254\241\344\275\234\344\270\232.md" "b/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\270\211\346\254\241\344\275\234\344\270\232.md" new file mode 100644 index 0000000..0828462 --- /dev/null +++ "b/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\270\211\346\254\241\344\275\234\344\270\232.md" @@ -0,0 +1,204 @@ +```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？ + + + +//工具类 +import java.sql.*; +public class DbJbdc { + private static final String url="jdbc:mysql:///student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + private static final String user="root"; + private static final String pass="root"; + public static Connection link() throws ClassNotFoundException, SQLException { + Class.forName("com.mysql.cj.jdbc.Driver"); + Connection conn = DriverManager.getConnection(url, user, pass); + return conn; + } + public static int currencyUpdate(String sql,String ...flop) throws SQLException, ClassNotFoundException { + Connection conn = link(); + PreparedStatement prs = conn.prepareStatement(sql); + for (int i = 0; i < flop.length; i++) { + prs.setString((i+1),flop[i]); + } + int i = prs.executeUpdate(); + return i; + } + public static int delete(String sql,String ...flop) throws SQLException, ClassNotFoundException { + int i = currencyUpdate(sql, flop); + return i; + } + public static int modify(String sql,String ...flop) throws SQLException, ClassNotFoundException { + int i = currencyUpdate(sql, flop); + return i; + } + public static int add(String sql,String ...flop) throws SQLException, ClassNotFoundException { + int i = currencyUpdate(sql, flop); + return i; + } + public static ResultSet Query(String sql,String ...flop) throws SQLException, ClassNotFoundException { + Connection conn = link(); + PreparedStatement prs = conn.prepareStatement(sql); + for (int i = 0; i < flop.length; i++) { + prs.setString((i+1),flop[i]); + } + ResultSet rs = prs.executeQuery(); + return rs; + } +} + + +查找 +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; +import java.sql.ResultSet; +import java.sql.SQLException; +@WebServlet("/seek") +public class Seek 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 { + String sql ="select * from student"; + ResultSet rs = DbJbdc.Query(sql); + while (rs.next()){ + int id = rs.getInt("id"); + String name = rs.getString("name"); + String sex = rs.getString("sex"); + resp.getWriter().write(id+" "+name+" "+sex+"
"); + } + } catch (SQLException e) { + e.printStackTrace(); + } catch (ClassNotFoundException e) { + e.printStackTrace(); + } + } + + @Override + protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + super.doPost(req, resp); + } +} + + +![/](tomcat\seek.png) + +//添加 +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; +import java.sql.SQLException; +@WebServlet("/add") +public class Add 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 { + String sql ="insert into student values (?,?,?)"; + int add = DbJbdc.add(sql, "0", "小海", "男"); + if (add>0){ + resp.getWriter().write("添加成功"); + }else { + resp.getWriter().write("添加失败"); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } + } + + @Override + protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + super.doPost(req, resp); + } +} + + + + +//删除 +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; +import java.sql.SQLException; +@WebServlet("/delete") +public class Delete 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 { + String sql ="delete from student where id=?"; + int add = DbJbdc.add(sql, "1"); + if (add>0){ + resp.getWriter().write("删除成功"); + }else { + resp.getWriter().write("删除失败"); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } + } + + @Override + protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + super.doPost(req, resp); + } +} + + +![](tomcat\delete.png) + +//修改 +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; +import java.sql.SQLException; +@WebServlet("/modify") +public class Modify 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 { + String sql ="update student set sex=? where id=?"; + int add = DbJbdc.add(sql, "女","2"); + if (add>0){ + resp.getWriter().write("修改成功"); + }else { + resp.getWriter().write("修改失败"); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } catch (ClassNotFoundException 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 diff --git "a/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\272\214\346\254\241\344\275\234\344\270\232.md" "b/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\272\214\346\254\241\344\275\234\344\270\232.md" index b16895f..a5873e1 100644 --- "a/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\272\214\346\254\241\344\275\234\344\270\232.md" +++ "b/30 \350\256\270\346\201\251\346\260\221/\347\254\254\344\272\214\346\254\241\344\275\234\344\270\232.md" @@ -94,5 +94,5 @@ class Test{ } DBUtil.close(null,null,res); } -} +} ``` \ No newline at end of file -- Gitee