比方说，某个用来在文件中查找特定单词的程序也许会扩展为在web页面中通过URL获取InputStream的操作。

For example, a program that looks for specific words in a file might be extended to work with Web pages by using the URL class to obtain an InputStream.

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例如，可以将nsswitch . conf文件配置为在文件中查找主机信息、查询DNS或使用NIS系统查找该信息。

For example, you can configure the nsswitch.conf file to look up host information in files, query the DNS, or use the NIS system to look up the information.

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借助hash索引，可以通过为记录生成一个hash值，然后根据这个hash值在文件中查找该记录，从而在固定的时间内在给定的文件中找到一条记录。

With a hash index you can find a record in a given file in constant time by generating a hash value for the record and then looking up the record in the file based on that hash value.

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