diff --git "a/14 \346\235\216\344\277\212\345\205\264/20230523 JDBC\347\275\221\351\241\265\350\277\236\346\216\245.md" "b/14 \346\235\216\344\277\212\345\205\264/20230523 JDBC\347\275\221\351\241\265\350\277\236\346\216\245.md" new file mode 100644 index 0000000000000000000000000000000000000000..f525a1c65ce2dd135e50cdb41165ba202f55f581 --- /dev/null +++ "b/14 \346\235\216\344\277\212\345\205\264/20230523 JDBC\347\275\221\351\241\265\350\277\236\346\216\245.md" @@ -0,0 +1,148 @@ +## Web连接数据库 + +## 查询 + +```java +import com.mysql.jdbc.util.ResultSetUtil; + +import java.sql.*; +import java.util.concurrent.locks.Condition; + +public class Day01 { + private static String url="jdbc:mysql:///student_db?useSSL=false&characterEncoding=utf8"; + private static String user="root"; + private static String password="root"; + static { + try { + Class.forName("com.mysql.jdbc.Driver"); + } catch (ClassNotFoundException e) { + e.printStackTrace(); + System.out.println("驱动包异常"); + } + } + public static Connection getconn(){ + Connection conn = null; + try { + conn = DriverManager.getConnection(url, user, password); + } catch (SQLException e) { + e.printStackTrace(); + } + return conn; + } + public static ResultSet query(String sql, String ...key){ + ResultSet rs = null; + try { + Connection ge = getconn(); + PreparedStatement prt = ge.prepareStatement(sql); + for (int i = 0; i < key.length; i++) { + prt.setString((i+1),key[i]); + } + rs = prt.executeQuery(); + } catch (SQLException e) { + e.printStackTrace(); + } + return rs; + } +} + +``` + +### 查询测试类 + +```java +@WebServlet("/stu") +public class SelectTest extends HttpServlet { + @Override + protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { + resp.setContentType("text/html;charset=utf-8"); + resp.setCharacterEncoding("utf-8"); + PrintWriter wr = resp.getWriter(); + String sql="select * from studen"; + ResultSet que =Select.query(sql); + wr.write("
| 编号 | 姓名 | 性别 |
|---|---|---|
| "+id+" | "+name+" | "+sex+" |