1

我正在尝试触发一个 http post 请求，我的问题是我得到了一个 NullpointerException，我想我知道在哪里，但我不知道为什么。

代码是

HttpURLConnection connection = null;
    try {
      URL url = new URL(targetURL);

      connection = (HttpURLConnection)url.openConnection();
      connection.setRequestMethod("POST");
      connection.setRequestProperty("Content-Type",
           "application/x-www-form-urlencoded");
      connection.setRequestProperty("Content-Length", "" +
               Integer.toString(urlParameters.getBytes().length));
      connection.setRequestProperty("Content-Language", "en-US");
      connection.setUseCaches (false);
      connection.setDoInput(true);
      connection.setDoOutput(true);

      // Send request
      DataOutputStream wr = new DataOutputStream (connection.getOutputStream());
      wr.writeBytes (urlParameters);
      wr.flush();
      wr.close();

      // Get Response
      InputStream is = connection.getInputStream();
      BufferedReader rd = new BufferedReader(new InputStreamReader(is));
      String line;
      StringBuffer response = new StringBuffer();
      while((line = rd.readLine()) != null) {
        response.append(line);
        response.append('\r');
      }
      rd.close();
      log.info("Http request response '{}': ",response.toString());

    } catch (Exception e) {
      log.error("Error while sending http post request.");
      e.printStackTrace();


    } finally {

      if(connection != null) {
        connection.disconnect();
      }
    }

我的错误输出是：

java.lang.NullPointerException
    at sun.net.www.ParseUtil.toURI(ParseUtil.java:261)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:905)
    at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:836)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1014)

在线：DataOutputStream wr = new DataOutputStream (connection.getOutputStream());

似乎问题是要建立一个 Http URL 连接，但我的目标 URL（我要发送请求的 URL）是正确的： Target url: 'http:localhost:8080/project/externalData' （它是我的 url (Spring) RequestMethod 在我的 url 模式中。而且我的参数字符串似乎是正确的 PARAMS：'salutation=Mister&givenname=Matt&familyname=Jones'。或者使用 DataOutputStream 是否正确？

感谢任何帮助:)

4

1 回答 1

2

我已经检查了您的代码，它工作正常。我猜 URL 有问题，要么是错误的，要么是 URL 有一些无法解析的字符。




import java.io.BufferedReader;




导入 java.io.DataOutputStream；
导入 java.io.InputStream；
导入 java.io.InputStreamReader；
导入 java.net.HttpURLConnection；
导入 java.net.URL；



公共类片段{



公共静态无效主要（字符串参数[]）{
    HttpURLConnection 连接 = 空；


 String targetURL="http://localhost:7001/smartquote_nodocuments/session";
 String urlParameters="timezoneOffset=-330&daylightSaving=false";
    try {

    URL url = new URL(targetURL);

      connection = (HttpURLConnection)url.openConnection();
      connection.setRequestMethod("POST");
      connection.setRequestProperty("Content-Type",
           "application/x-www-form-urlencoded");

    connection.setRequestProperty("Content-Length", "" +
               Integer.toString(urlParameters.getBytes().length));
      connection.setRequestProperty("Content-Language", "en-US");
      connection.setUseCaches (false);
      connection.setDoInput(true);
      connection.setDoOutput(true);

      // Send request
      DataOutputStream wr = new DataOutputStream (connection.getOutputStream());
      wr.writeBytes (urlParameters);
      wr.flush();
      wr.close();

      // Get Response
      InputStream is = connection.getInputStream();
      BufferedReader rd = new BufferedReader(new InputStreamReader(is));
      String line;
      StringBuffer response = new StringBuffer();
      while((line = rd.readLine()) != null) {
        response.append(line);
        response.append('\r');
      }
      rd.close();
      System.out.println("Http request response '{}': "+response.toString());
    }catch(Exception e){
        e.printStackTrace();
    }}}

它工作正常并给出了预期的结果

于 2013-08-30T07:54:59.713 回答