优化这段代码import tkinter import pymysql def logincheck(root,inputuser,inputpwd): userval = inputuser.get() pwdval = inputpwd.get() db = pymysql.connect(host="127.0.0.1",port=3306,user='root',passwd='12345678',db='AICarNumber') cursor = db.cursor() sqlstr = "select * from user where username='"+userval+"'and pwd='"+pwdval+"'" cursor.execute(sqlstr) results = cursor.fetchall() if (len(results) >0): print("验证通过!") root.quit() root.destroy() else: print("验证失败!") db.close() def reset(): name = username.set('') pwd = passwd.set('') print(name,pwd) tkinter.showinfo('成功','重置成功') username = '' passwd = '' def login(): print("login...") root = tkinter.Tk() root.title("登录界面") root.geometry("250x70") username = tkinter.StringVar() passwd = tkinter.StringVar() tkinter.Label(root,text="用户名:").grid(row=0) tkinter.Label(root,text="密码").grid(row=1) tkinter.Entry(root,textvariable=username).grid(row=0,column=1) tkinter.Entry(root,textvariable=passwd,show='$').grid(row=1,column=1) tkinter.Button(root,text="登录",command=(lambda tk=root,x=username,y=passwd:logincheck(tk,x,y)))\ .grid(row=0,column=2,rowspan=2) resetNome_login = tkinter.Button(root, text='退出', command=reset) resetNome_login.grid(row=2,column=2) root.mainloop() if __name__ =='__main__': login()

这段代码可以进行如下优化： 1. 使用with语句来自动关闭数据库连接，避免忘记关闭而导致的资源泄露。 2. 使用参数化查询来避免SQL注入攻击，将用户输入的值作为参数传递给查询语句。 3. 将重置函数reset()中的全局变量username和passwd改为局部变量，避免与输入框的变量名重复。 4. 将重置函数reset()重命名为clear()，更符合其实际功能。 5. 优化代码结构，将登录窗口的创建和显示分离成两个函数，使代码更加清晰易懂。 下面是优化后的代码： ``` import tkinter import pymysql def clear(username_entry, passwd_entry): username_entry.delete(0, tkinter.END) passwd_entry.delete(0, tkinter.END) tkinter.messagebox.showinfo('成功','重置成功') def logincheck(root, username_entry, passwd_entry): userval = username_entry.get() pwdval = passwd_entry.get() with pymysql.connect(host="127.0.0.1", port=3306, user='root', passwd='12345678', db='AICarNumber') as cursor: sqlstr = "select * from user where username=%s and pwd=%s" cursor.execute(sqlstr, (userval, pwdval)) results = cursor.fetchall() if len(results) > 0: print("验证通过!") root.quit() root.destroy() else: print("验证失败!") def create_login_window(): root = tkinter.Tk() root.title("登录界面") root.geometry("250x70") username_entry = tkinter.Entry(root) passwd_entry = tkinter.Entry(root, show='$') username_entry.grid(row=0,column=1) passwd_entry.grid(row=1,column=1) tkinter.Label(root,text="用户名:").grid(row=0) tkinter.Label(root,text="密码").grid(row=1) tkinter.Button(root,text="登录",command=(lambda tk=root,x=username_entry,y=passwd_entry:logincheck(tk,x,y))).grid(row=0,column=2,rowspan=2) tkinter.Button(root, text='重置', command=(lambda x=username_entry, y=passwd_entry: clear(x,y))).grid(row=2,column=1) tkinter.Button(root, text='退出', command=root.quit).grid(row=2,column=2) return root def show_login_window(): login_window = create_login_window() login_window.mainloop() if __name__ =='__main__': show_login_window() ```