2020.07.02 發送 POST 請求出現異常！java.io.IOException: Server returned HTTP response code: 400 for URL:

url能正常打開，報錯Server returned HTTP response code: 400 for URL:

解決代碼如下：

/**
	 * 發送 WebService 請求
	 * @param content 請求內容
	 * @param wsdlUrl 請求地址
	 * @param soapAction 請求方法
	 * @return
	 */
	public static String postToWebservice(String content, String wsdlUrl, String soapAction){
		OutputStreamWriter out = null;
		BufferedReader in = null;
		String result = "";
		try {
			URL realUrl = new URL(wsdlUrl);
			// 打開和URL之間的連接
			HttpURLConnection  conn = (HttpURLConnection) realUrl.openConnection();
			// 設置通用的請求屬性
			conn.setRequestProperty("accept", "*/*");
			conn.setRequestProperty("connection", "Keep-Alive");
			conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
			conn.setRequestProperty("Content-Type", "text/xml; charset=utf-8");
			conn.setRequestProperty("SOAPAction", soapAction);
			// 發送POST請求必須設置如下兩行
			conn.setDoOutput(true);
			conn.setDoInput(true);
			// 獲取URLConnection對象對應的輸出流
			// out = new PrintWriter(conn.getOutputStream());
			out = new OutputStreamWriter(conn.getOutputStream(), "utf-8"); // 8859_1
			out.write(content); // post的關鍵所在
			// 發送請求參數
			// out.print(param);
			// flush輸出流的緩衝
			out.flush();
			// 定義BufferedReader輸入流來讀取URL的響應
			int code = conn.getResponseCode();
			if(code == 200) {
				in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
			}else{
				in = new BufferedReader(new InputStreamReader(conn.getErrorStream()));
			}
			String line;
			while ((line = in.readLine()) != null) {
				result += line;
			}
		}catch (MalformedURLException e) {
			LogFactory.info("exception MalformedURLException: "+e.getMessage(), TAG);
			e.printStackTrace();
		} catch (ProtocolException e) {
			LogFactory.info("exception ProtocolException: "+e.getMessage(), TAG);
			e.printStackTrace();
		} catch (IOException e) {
			LogFactory.info("exception IOException: "+e.getMessage(), TAG);
			e.printStackTrace();
		}
		// 使用finally塊來關閉輸出流、輸入流
		finally {
			try {
				if (out != null) {
					out.close();
				}
				if (in != null) {
					in.close();
				}
			} catch (IOException ex) {
				ex.printStackTrace();
			}
		}
		return result;

	}