我正在创建在Java HttpServer类上运行的服务器，一切正常，但是我注意到对exchange.getRemoteAddress().getAddress().getCanonicalHostName()的调用大约需要4000毫秒，但是即使删除getRemoteAddress（），读取请求正文也很快。有谁知道为什么HttpExchange.getRemoteAddress（）需要这么长时间？
从服务器登录：
[pool-1-thread-1 | 13:25:54] Received request from 192.168.0.104 / Obtaining remote address took 4538 ms
[pool-1-thread-1 | 13:25:54] Downloading request body from 192.168.0.104 took 0 ms
[pool-1-thread-1 | 13:25:54] Generating response body from 192.168.0.104 took 6 ms
[pool-1-thread-1 | 13:25:54] Processing lock request from 192.168.0.104
将exchange.getRemoteAddress().getAddress().getCanonicalHostName()替换为硬编码字符串（“测试”）时记录：
[pool-1-thread-1 | 13:28:00] Received request from test / Obtaining remote address took 0 ms
[pool-1-thread-1 | 13:28:00] Downloading request body from test took 1 ms
[pool-1-thread-1 | 13:28:00] Generating response body from test took 7 ms
[pool-1-thread-1 | 13:28:00] Processing lock request from test
编辑：
我的失败，没有正确阅读getCanonicalHostName()文档。它清楚地说
获取此IP地址的标准域名。最大努力 方法，这意味着我们可能无法返回FQDN，具体取决于 基础系统配置。
替换为getHostAddress()
答案 0 :(得分：1)
这是因为查找给定IP地址的主机名通常会涉及reverse DNS lookup，即网络查询（或一系列查询），这是一项昂贵的操作，并且比使用硬编码的字符串值要慢得多