用Vigenere密码算法加解密文本文件中的文本信息，设密钥长度为7，密钥在程序执行时动态输入，加密得到的密文放在另一个文本文件中，设计的程序要有界面。

好的，我可以为您提供一个Python程序实现您的要求。以下是代码：

from tkinter import *
from tkinter import filedialog

ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

def vigenere_cipher(plaintext, key):
    ciphertext = ""
    key_index = 0
    for letter in plaintext:
        if letter.isalpha():
            shift = ALPHABET.index(key[key_index].upper())
            cipher_letter = ALPHABET[(ALPHABET.index(letter.upper()) + shift) % 26]
            if letter.islower():
                cipher_letter = cipher_letter.lower()
            ciphertext += cipher_letter
            key_index = (key_index + 1) % len(key)
        else:
            ciphertext += letter
    return ciphertext

def vigenere_decipher(ciphertext, key):
    plaintext = ""
    key_index = 0
    for letter in ciphertext:
        if letter.isalpha():
            shift = ALPHABET.index(key[key_index].upper())
            plain_letter = ALPHABET[(ALPHABET.index(letter.upper()) - shift) % 26]
            if letter.islower():
                plain_letter = plain_letter.lower()
            plaintext += plain_letter
            key_index = (key_index + 1) % len(key)
        else:
            plaintext += letter
    return plaintext

def browse_file():
    file_path = filedialog.askopenfilename()
    file_path_entry.delete(0, END)
    file_path_entry.insert(0, file_path)

def browse_save_file():
    file_path = filedialog.asksaveasfilename(defaultextension=".txt")
    save_file_path_entry.delete(0, END)
    save_file_path_entry.insert(0, file_path)

def encrypt_file():
    file_path = file_path_entry.get()
    save_file_path = save_file_path_entry.get()
    key = key_entry.get()
    if file_path and save_file_path and key:
        with open(file_path, "r") as file:
            plaintext = file.read()
            ciphertext = vigenere_cipher(plaintext, key)
            with open(save_file_path, "w") as save_file:
                save_file.write(ciphertext)
        result_label.config(text="Encryption completed.")
    else:
        result_label.config(text="Please fill in all fields.")

def decrypt_file():
    file_path = file_path_entry.get()
    save_file_path = save_file_path_entry.get()
    key = key_entry.get()
    if file_path and save_file_path and key:
        with open(file_path, "r") as file:
            ciphertext = file.read()
            plaintext = vigenere_decipher(ciphertext, key)
            with open(save_file_path, "w") as save_file:
                save_file.write(plaintext)
        result_label.config(text="Decryption completed.")
    else:
        result_label.config(text="Please fill in all fields.")

root = Tk()
root.title("Vigenere Cipher")

file_path_label = Label(root, text="Select File:")
file_path_label.grid(row=0, column=0, padx=5, pady=5, sticky=W)

file_path_entry = Entry(root, width=50)
file_path_entry.grid(row=0, column=1, padx=5, pady=5)

browse_button = Button(root, text="Browse", command=browse_file)
browse_button.grid(row=0, column=2, padx=5, pady=5)

save_file_path_label = Label(root, text="Save File As:")
save_file_path_label.grid(row=1, column=0, padx=5, pady=5, sticky=W)

save_file_path_entry = Entry(root, width=50)
save_file_path_entry.grid(row=1, column=1, padx=5, pady=5)

browse_save_button = Button(root, text="Browse", command=browse_save_file)
browse_save_button.grid(row=1, column=2, padx=5, pady=5)

key_label = Label(root, text="Enter Key:")
key_label.grid(row=2, column=0, padx=5, pady=5, sticky=W)

key_entry = Entry(root, width=50)
key_entry.grid(row=2, column=1, padx=5, pady=5)

encrypt_button = Button(root, text="Encrypt", command=encrypt_file)
encrypt_button.grid(row=3, column=0, padx=5, pady=5)

decrypt_button = Button(root, text="Decrypt", command=decrypt_file)
decrypt_button.grid(row=3, column=1, padx=5, pady=5)

result_label = Label(root, text="")
result_label.grid(row=4, column=0, columnspan=2, padx=5, pady=5)

root.mainloop()

通过运行该程序，您将获得一个简单的GUI界面，您可以在其中选择要加密/解密的文件，选择保存位置，动态输入密钥并执行操作。请注意，这个程序假定文件中的文本只包含英文字符（大写/小写）和标点符号。如果您的文件中有其他字符，请先处理它们，否则程序可能会出错。