Java URLConnection - 我什么时候需要使用connect（）方法？ [英] Java URLConnection - When do I need to use the connect() method?

问题描述

我有一个问题需要理解 URLConnection 类中 connect（）方法的含义。在下面的代码中，如果我使用 connect（）方法，如果我不使用它，我会得到相同的结果。

I have a problem to understand the meaning of the connect() method in the URLConnection class. In the following code, if I use the connect() method, I get the same result if I don't use it.

为什么（或何时）我需要使用它？

Why (or when) do I need to use it?

URL u = new URL("http://example.com");
HttpURLConnection conn = (HttpURLConnection) u.openConnection();

conn.connect();//with or without it I have the same result

InputStream in = conn.getInputStream();
int b;
while ((b = in.read()) != -1) {
 System.out.write(b);
}

推荐答案

您并不总是需要显式调用connect方法以启动连接。

You are not always required to explicitly call the connect method to initiate the connection.

依赖于连接的操作，例如 getInputStream ， getOutputStream 等将隐式执行连接。

Operations that depend on being connected, like getInputStream, getOutputStream, etc, will implicitly perform the connection, if necessary.

这是oracle doc link

Here's the oracle doc link

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