Java - 通过POST方法轻松发送HTTP参数 [英] Java - sending HTTP parameters via POST method easily

问题描述

我成功使用此代码通过 GET 方法

I am successfully using this code to send HTTP requests with some parameters via GET method

void sendRequest(String request)
{
    // i.e.: request = "http://example.com/index.php?param1=a&param2=b&param3=c";
    URL url = new URL(request); 
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();           
    connection.setDoOutput(true); 
    connection.setInstanceFollowRedirects(false); 
    connection.setRequestMethod("GET"); 
    connection.setRequestProperty("Content-Type", "text/plain"); 
    connection.setRequestProperty("charset", "utf-8");
    connection.connect();
}

现在我可能需要发送参数（即param1，param2，param3）通过 POST 方法，因为它们非常长。
我想在该方法中添加一个额外的参数（即字符串httpMethod）。

Now I may need to send the parameters (i.e. param1, param2, param3) via POST method because they are very long. I was thinking to add an extra parameter to that method (i.e. String httpMethod).

如何能够尽可能少地更改上面的代码才能够通过 GET 或 POST 发送参数？

How can I change the code above as little as possible to be able to send paramters either via GET or POST?

我希望改变

connection.setRequestMethod("GET");

到

connection.setRequestMethod("POST");

可以做到这一点，但参数仍然是通过GET方法发送的。

would have done the trick, but the parameters are still sent via GET method.

有 HttpURLConnection 有任何方法可以提供帮助吗？
是否有任何有用的Java构造？

Has HttpURLConnection got any method that would help? Is there any helpful Java construct?

非常感谢任何帮助。

推荐答案

在GET请求中，参数作为URL的一部分发送。

In a GET request, the parameters are sent as part of the URL.

在POST请求中，参数作为a请求的主体，在标题之后。

In a POST request, the parameters are sent as a body of the request, after the headers.

要使用HttpURLConnection执行POST，您需要在打开连接后将参数写入连接。

To do a POST with HttpURLConnection, you need to write the parameters to the connection after you have opened the connection.

此代码可以帮助您入门：

This code should get you started:

String urlParameters  = "param1=a&param2=b&param3=c";
byte[] postData       = urlParameters.getBytes( StandardCharsets.UTF_8 );
int    postDataLength = postData.length;
String request        = "http://example.com/index.php";
URL    url            = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnection();           
conn.setDoOutput( true );
conn.setInstanceFollowRedirects( false );
conn.setRequestMethod( "POST" );
conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded"); 
conn.setRequestProperty( "charset", "utf-8");
conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
conn.setUseCaches( false );
try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
   wr.write( postData );
}

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