如何使用HttpUrlConnection發送POST請求中的requestparameter

Question

我需要向URL發送POST請求併發送一些請求參數。我爲此使用HttpURLConnectionAPI。但我的問題是我沒有得到servlet中的任何請求參數。雖然我看到參數存在於請求主體中，但是當我使用request.getReader打印請求主體時。以下是客戶端代碼。任何機構可以指定這是否是在POST請求中發送請求參數的正確方法？

String urlstr = "http://serverAddress/webappname/TestServlet"; 

String params = "&paramname=paramvalue"; 

URL url = new URL(urlstr); 

HttpURLConnection urlconn = (HttpURLConnection) url.openConnection(); 

urlconn.setDoInput(true); 

urlconn.setDoOutput(true); 

urlconn.setRequestMethod("POST"); 

urlconn.setRequestProperty("Content-Type", "text/xml"); 

urlconn.setRequestProperty("Content-Length", String.valueOf(params.getBytes().length)); 

urlconn.setRequestProperty("Content-Language", "en-US"); 

OutputStream os = urlconn.getOutputStream(); 

BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8")); 

writer.write(params); 

writer.close(); 

os.close(); 

Answer 1

像@Kal說，擺脫了領先&，並且不與理會的BufferedWriter。這適用於我：

byte[] bytes = parameters.getBytes("UTF-8"); 
httpUrlConnection.setRequestProperty("Content-Length", String.valueOf(bytes.length)); 
httpUrlConnection.setRequestMethod("POST"); 
httpUrlConnection.setDoOutput(true); 
httpUrlConnection.connect(); 
outputStream = httpUrlConnection.getOutputStream(); 
outputStream.write(bytes); 

Answer 2

要更清潔，您可以編碼以發送值。

String data = URLEncoder.encode("key1", "UTF-8") + "=" + URLEncoder.encode("value1", "UTF-8"); 
data += "&" + URLEncoder.encode("key2", "UTF-8") + "=" + URLEncoder.encode("value2", "UTF-8"); 

URL url = new URL("http://yourserver.com/whatever"); 
URLConnection conn = url.openConnection(); 
conn.setDoOutput(true); 
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream()); 
wr.write(data);