From 986048006680a6ecc88ba9fd7e474f7d2cf677a4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E9=BB=84=E6=AD=A3=E7=84=95?= <1953038944@qq.com> Date: Thu, 25 May 2023 23:34:22 +0800 Subject: [PATCH] =?UTF-8?q?=E7=AC=AC=E5=9B=9B=E6=AC=A1=E4=BD=9C=E4=B8=9A?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...a-\346\225\260\346\215\256\345\272\223.md" | 238 ++++++++++++++++++ 1 file changed, 238 insertions(+) create mode 100644 "38 \351\273\204\346\255\243\347\204\225/20230524 \347\275\221\351\241\265-java-\346\225\260\346\215\256\345\272\223.md" diff --git "a/38 \351\273\204\346\255\243\347\204\225/20230524 \347\275\221\351\241\265-java-\346\225\260\346\215\256\345\272\223.md" "b/38 \351\273\204\346\255\243\347\204\225/20230524 \347\275\221\351\241\265-java-\346\225\260\346\215\256\345\272\223.md" new file mode 100644 index 0000000..2478f70 --- /dev/null +++ "b/38 \351\273\204\346\255\243\347\204\225/20230524 \347\275\221\351\241\265-java-\346\225\260\346\215\256\345\272\223.md" @@ -0,0 +1,238 @@ +```mysql +create database student_db character set utf8; +use student_db; +create table student( +stuid int, +stuname varchar(10), +stusex varchar(2) +); +insert into student values(1,"张三","男"); +insert into student values(2,"李四","女"); +insert into student values(3,"王五","男"); +``` + +```java +//工具类 +import java.sql.*; + +public class JDBCUtil { + private static final String url = "jdbc:mysql://localhost:3306/student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + private static final String username = "root"; + private static final String password = ""; + //注册驱动的方法 + //用静态代码块，注册驱动，{}表示代码块，static表示静态的，最先执行 + static { + try { + Class.forName("com.mysql.jdbc.Driver"); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } + } + //获取连接对象的方法 + public static Connection getConn() throws SQLException { + Connection conn = DriverManager.getConnection(url, username, password); + return conn; + } + + /** + * 通用的query + * @param sql 接收的SQL语句 + * @return 将查询的结果集返回给调用者 + */ + public static ResultSet query(String sql,String ...keys) throws SQLException { + Connection conn = getConn(); + PreparedStatement pst = conn.prepareStatement(sql); + for (int i = 0; i < keys.length; i++) { + pst.setString(i+1,keys[i]); + } + ResultSet rst = pst.executeQuery(); + return rst; + + } + + + + //通用的update + public static int update(String sql,String ...keys) throws SQLException { + Connection conn = getConn(); + PreparedStatement pst = conn.prepareStatement(sql); + for (int i = 0; i < keys.length; i++) { + pst.setString(i+1,keys[i]); + } + int i = pst.executeUpdate(); + return i; + + } + + //通用的释放资源的方法 + public static void close(Connection conn,PreparedStatement pst,ResultSet rst){ + try { + if (rst!=null){ + rst.close(); + } + if (pst!=null){ + rst.close(); + } + if (conn!=null){ + rst.close(); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } + } +} + +``` + +```java + + + + + + 增删改 + + + +

添加学生

+
+ 编号：
+ 姓名：
+ 性别：
+ +
+ +

修改学生信息

+
+ 编号：
+ 姓名：
+ 性别：
+ + +
+ +

删除学生信息

+
+ 编号：
+ + +
+ +

查询学生信息

+
+ 编号：
+ 姓名：
+ 性别：
+ +
+ + + + + +``` + +```java +//代码 +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("/student") +public class add extends HttpServlet { + @Override + protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + + } + + @Override + protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + req.setCharacterEncoding("utf-8");//设置字符集，防止乱码 + //添加学生 + String stuid = req.getParameter("stuid"); + String stuname = req.getParameter("stuname"); + String stusex = req.getParameter("stusex"); + if (stuid!=null) { + //sql语句 + String sql = "insert into student values(?,?,?)"; + resp.setContentType("text/html;charset=utf-8"); + try { + int i = JDBCUtil.update(sql, stuid, stuname, stusex); + if (i > 0) { + resp.getWriter().write("添加成功！"); + } else { + resp.getWriter().write("添加失败！"); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } + } + String stuid1 = req.getParameter("stuid1"); + String stuname1 = req.getParameter("stuname1"); + + + //修改学生信息 + if (stuid1!=null) { + String sql1 = "update student set stuname=? where stuid=? "; + resp.setContentType("text/html;charset=utf-8"); + try { + int i = JDBCUtil.update(sql1, stuname1, stuid1); + if (i > 0) { + resp.getWriter().write("修改成功！"); + } else { + resp.getWriter().write("修改失败!"); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } + } + + //删除学生 + String stuid2 = req.getParameter("stuid2"); + + if (stuid2!=null){ + String sql2 = "delete from student where stuid=?"; + resp.setContentType("text/html;charset=utf-8"); + try { + int i = JDBCUtil.update(sql2,stuid2); + if (i>0){ + resp.getWriter().write("删除成功！"); + }else { + resp.getWriter().write("删除失败!"); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } + + } + //查询学生信息 + String stuid3 = req.getParameter("stuid3"); + + if (stuid3!=null){ + resp.setContentType("text/html;charset=utf-8"); + resp.setContentType("text/html;charset=utf-8"); + String sql3 = "select * from student where stuid=?"; + + try { + ResultSet rs = JDBCUtil.query(sql3, stuid3); + while (rs.next()){ + int sid = rs.getInt("stuid"); + String sname = rs.getString("stuname"); + String ssex = rs.getString("stusex"); + resp.getWriter().write(sid+" "+sname+" "+ssex); + } + } catch (SQLException e) { + throw new RuntimeException(e); + } + + } + + } +} + +``` + -- Gitee