Java URLConnection - 我什么时候需要使用 connect() 方法？
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Java URLConnection - When do I need to use the connect() method?
提问by kappa
I have a problem to understand the meaning of the connect()method in the URLConnectionclass. In the following code, if I use the connect()method, I get the same result if I don't use it.
我在理解类中connect()方法的含义时遇到了问题URLConnection。在下面的代码中，如果我使用该connect()方法，如果我不使用它，我会得到相同的结果。
Why (or when) do I need to use it?
为什么（或何时）我需要使用它？
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);
}
回答by swagat
You are not always required to explicitly call the connect method to initiate the connection.
您并不总是需要显式调用 connect 方法来启动连接。
Operations that depend on being connected, like getInputStream, getOutputStream, etc, will implicitly perform the connection, if necessary.
如有必要，依赖于连接的操作（如getInputStream、getOutputStream等）将隐式执行连接。
Here's the oracle doc link
这是 oracle 文档链接
回答by Amanda
HttpURLConnection conn = (HttpURLConnection) u.openConnection();
only creates an Object
只创建一个对象
connect()method is invoked by conn.getInputStream();
connect()方法被调用 conn.getInputStream();
