Java连接mysql及增删改查操作

public class DButil {public static final String Driver = "com.mysql.jdbc.Driver";public static final String Username = "root";public static final String Password = "root";public static final String Url = "jdbc:mysql://localhost:3306/login";Connection conn = null;int result;int i;//加载数据库public void initDB() {try {Class.forName(Driver);System.out.println("加载成功");} catch (Exception e) {}}//连接数据库public Connection connectionDB() {try {conn=DriverManager.getConnection(Url,Username,Password);System.out.println("连接成功");} catch (Exception e) {}return conn;}//关闭数据库public void closeDB() {try {conn.close();} catch (Exception e) {}}//查询public int selectDB(String username,String password) {try {String sql = "Select * from login where username = '" + username + "' and password = '"+ password +"'";Statement stmt=conn.createStatement();ResultSet rs = stmt.executeQuery(sql);if(rs.next())result=1;else {result=0;}} catch (Exception e) {}return result;}//插入public int insertDB(String username,String password) {try {String sql = "insert into login(username,password) values('" + username + "','" + password + "')";PreparedStatement pstmt = conn.prepareStatement(sql);i=pstmt.executeUpdate();}catch (Exception e) {}return i;}} public class DButil {public static final String