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"
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+++ "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
+
+
+修改学生信息
+
+
+删除学生信息
+
+
+查询学生信息
+
+
+
+
+
+
+```
+
+```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);
+ }
+
+ }
+
+ }
+}
+
+```
+