java之网上淘书吧系统的demo学习与演示

package beans; import java.io.PrintStream; import java.sql.*; public class connDB { private static Connection conn = null; private static Statement stmt = null; private static ResultSet rs = null; private static final String driverClass = "com.microsoft.sqlserver.jdbc.SQLServerDriver"; private static final String URL = "jdbc:sqlserver://localhost:1433;DatabaseName=db_bookmanage"; private static final String user = "sa"; private static final String pwd = "111"; public connDB() { try { Class.forName(driverClass); conn = DriverManager.getConnection(URL,user,pwd); } catch (Exception e) { e.printStackTrace(); } } public ResultSet executeQuery(String sql) { try { stmt = conn.createStatement(1004, 1007); rs = stmt.executeQuery(sql); } catch(SQLException ex) { System.err.println(ex.getMessage()); } return rs; } public int executeUpdate(String sql) { int result = 0; try { stmt = conn.createStatement(1004, 1007); result = stmt.executeUpdate(sql); } catch(SQLException ex) { result = 0; } return result; } public int executeUpdate_id(String sql) { int result = 0; try { stmt = conn.createStatement(1004, 1007); result = stmt.executeUpdate(sql); String ID = "select @@IDENTITY as id"; rs = stmt.executeQuery(ID); if(rs.next()) { int autoID = rs.getInt("id"); result = autoID; } } catch(SQLException ex) { result = 0; } return result; } public void close() { try { if(rs != null) rs.close(); if(stmt != null) stmt.close(); if(conn != null) conn.close(); } catch(Exception e) { e.printStackTrace(System.err); } } }