Python怎样实现文档比对？difflib库技巧

import difflib

def compare_files(file1, file2):
    """
    对比两个文本文件，并返回差异结果。
    """
    try:
        with open(file1, 'r', encoding='utf-8') as f1, open(file2, 'r', encoding='utf-8') as f2:
            text1 = f1.readlines()
            text2 = f2.readlines()
    except FileNotFoundError:
        return "文件未找到"
    except Exception as e:
        return f"读取文件出错: {e}"

    d = difflib.Differ()
    diff = d.compare(text1, text2)
    return list(diff)

# 示例用法
file1 = "file1.txt"
file2 = "file2.txt"
diff_result = compare_files(file1, file2)

if isinstance(diff_result, list):
    for line in diff_result:
        print(line, end='')
else:
    print(diff_result)

import difflib

def generate_html_diff(file1, file2, output_file="diff.html"):
    """
    生成两个文本文件的HTML差异报告。
    """
    try:
        with open(file1, 'r', encoding='utf-8') as f1, open(file2, 'r', encoding='utf-8') as f2:
            text1 = f1.readlines()
            text2 = f2.readlines()
    except FileNotFoundError:
        return "文件未找到"
    except Exception as e:
        return f"读取文件出错: {e}"

    d = difflib.HtmlDiff()
    html_diff = d.make_file(text1, text2, file1, file2)

    try:
        with open(output_file, 'w', encoding='utf-8') as f:
            f.write(html_diff)
        return f"HTML差异报告已生成: {output_file}"
    except Exception as e:
        return f"写入HTML文件出错: {e}"

# 示例用法
file1 = "file1.txt"
file2 = "file2.txt"
result = generate_html_diff(file1, file2)
print(result)

import difflib
import time

def compare_large_files(file1, file2):
    """
    对比大型文本文件，并使用SequenceMatcher优化性能。
    """
    try:
        with open(file1, 'r', encoding='utf-8') as f1, open(file2, 'r', encoding='utf-8') as f2:
            text1 = f1.read()
            text2 = f2.read()
    except FileNotFoundError:
        return "文件未找到"
    except Exception as e:
        return f"读取文件出错: {e}"

    s = difflib.SequenceMatcher(None, text1, text2)
    diff = []
    for tag, i1, i2, j1, j2 in s.get_opcodes():
        if tag != 'equal':
            diff.append((tag, text1[i1:i2], text2[j1:j2]))
    return diff

# 示例用法
file1 = "large_file1.txt"
file2 = "large_file2.txt"

start_time = time.time()
diff_result = compare_large_files(file1, file2)
end_time = time.time()

print(f"比较耗时: {end_time - start_time:.2f} 秒")

# 打印差异结果 (只打印前10个差异)
for i, (tag, t1, t2) in enumerate(diff_result[:10]):
    print(f"差异 {i+1}:")
    print(f"  类型: {tag}")
    print(f"  文件1: {t1[:50]}...") # 只显示前50个字符
    print(f"  文件2: {t2[:50]}...") # 只显示前50个字符
    print("-" * 20)