# 不太确定是不是听懂了最后讲的，通过with语句调用自定义异常的内容。不知道是不是应该像下面这样编写代码： class CustomException(Exception): def __init__(self, message): self.message = message super().__init__(self.message) def __enter__(self): return self def __exit__(self, exc_type, exc_value, traceback): if self.message: print('文件不能小于10个字符') with open('./b.txt','r') as f: content = f.read() try: if len(content) < 10: with CustomException(True): pass except CustomException as ce: print(ce) else: with open('./b.txt', 'r') as f: print(f.read())

class Filesize_Error(Exception): @property def filesize(self): return f"文件过小，存在异常" with open('demo2.txt',mode='r',encoding='UTF-8') as f: try: data=f.read() if len(data)<10: raise Filesize_Error except Filesize_Error as fe: print(fe.filesize) else: print(data)

class FileLessException(Exception): def __init__(self, byte): self.msg = "File is less than 10 bytes" self.bytes = byte @property def input(self): return f"读取到文件字节数是{self.bytes},"+self.msg if __name__ == '__main__': try: with open('test.txt', 'r') as f: contents = f.read() if len(contents) < 10: raise FileLessException(len(contents)) else: print(f"读取到内容：{contents}") except FileLessException as e: print('error:', e.input) finally: print('程序运行结束')

class MyException(Exception): def __init__(self, message) -> None: self.message = message @property def msg(self): return self.message try: with open('./a.txt') as f: if len(f.read()) < 10: raise MyException("文件过小") print(f.read()) except MyException as e: print(e.msg)

class SizeError(Exception): def __init__(self, filename): self.filename = filename @property def more_than_10(self): return f"{self.filename}不能小于10个字符" filename = 'a.txt' try: with open(filename) as f: if len(f.read()) < 10: raise SizeError(filename) except SizeError as se: print(se.more_than_10)

'''编写自定义异常类，如果读取的文件小于 10 个字符，抛出文件过小的自定义异常，如果读取的文件大于等于 10 个字符，则正常输出该文件内容。''' from os import path file_name = input('please input the file name and suffix:') file_path = path.abspath(file_name) class MyException(Exception): def __init__(self, bv): self.bv = bv def check(self): if self.bv: print('文件小于10个字符') try: with open(file_path, 'r') as f: content = f.read() if len(content) < 10: raise MyException(True) except MyException as me: me.check() else: with open(file_path, 'r') as f: print(f.read())

# %% class SmallError(Exception): def __init__(self, size): self.size = size @property def msg(self): return f"file size=={self.size}. too small!" # %% try: with open("f1.txt") as f: cnt = f.read() if len(cnt) < 10: raise SmallError(len(cnt)) except SmallError as se: print(se.msg) else: print(cnt) finally: print("done.")

class NumError(Exception): def __init__(self, filename, num): self.filename = filename self.num = num @property def msn(self): return f"文件{self.filename}中的字符数为:{self.num},小于 10 个字符限制" file = "userData.txt" with open(file, 'r') as f: file_read = f.read() # 获取文件中字符数量 file_len = len(file_read) try: if file_len >= 10: print(file_read) else: raise NumError(file, file_len) except NumError as e: print(e.msn)

class NameError(Exception): '''自定义异常类，如果读取的文件小于 10 个字符，抛出文件过小的自定义异常''' def __init__(self, message, filename): self.message = message self.name = filename @property def msg(self): return f"文件长度{self.message} 小于10个字符. {self.name}文件不允许使用 " fname = './a.txt' try: with open (fname, 'r') as f: # 读取文件大小 strF=f.read() flen = len(strF) if flen <= 10 : raise NameError(flen,fname) except NameError as ne: # 文件小于 10 个字符，抛出文件过小的自定义异常 print(ne.msg) else: # 读取的文件大于等于 10 个字符，正常输出该文件内容。 print(strF)

class FileLengthError(Exception): def __init__(self, message): self.message = message @property def msg(self): return f"当前文件是{self.message}字符数，小于10个字符" file = "./a.txt" # 内容是 Hello with open(file) as f: fconten = f.read() try: flen = len(fconten) if flen < 10: raise FileLengthError(flen) else: print(fconten) except FileLengthError as fe: print(fe.msg) #结果是：当前文件是6字符数，小于10个字符