如何替换文本文件中的字符串并将其保存到新文件中？

def replace_text(source_file, target_file, old_str, new_str):
    try:
        # 读取源文件内容
        with open(source_file, 'r') as file:
            content = file.read()

        # 替换字符串
        replaced_content = content.replace(old_str, new_str)

        # 创建新文件并写入替换后的内容
        with open(target_file, 'w') as file:
            file.write(replaced_content)

        print("字符串替换成功！")
    except Exception as e:
        print("字符串替换失败：", str(e))

# 使用示例
source_file = "source.txt"
target_file = "target.txt"
old_str = "old_string"
new_str = "new_string"

replace_text(source_file, target_file, old_str, new_str)