Question

使用以下代码，服务器受到攻击，但我也想在POST方法中发送变量。

但它只是给了我一个空指针异常。它与OutputStream有关。我检查了postData ...它有一些地址，这意味着它不是空的。

那么为什么我被赋予空指针异常？

ConnectionFactory connFact = new ConnectionFactory();
ConnectionDescriptor connDesc;
try {
    connDesc = connFact.getConnection("http://example.com/login.php", Connector.READ_WRITE, returnContent);
    httpConn.setRequestMethod(HttpConnection.POST);
    httpConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

    URLEncodedPostData encPostData = new URLEncodedPostData("UTF-8", false);
    encPostData.append("count", "Hell Yeah!");
    byte[] postData = encPostData.toString().getBytes("UTF-8");

    httpConn.setRequestProperty("Content-length", String.valueOf(postData.length));
    Dialog.alert("Post Data: " + postData);

    OutputStream os = httpConn.openOutputStream();
    os.write(postData);
    os.flush();
    httpConn = (HttpConnection) connDesc.getConnection();

    final int iResponseCode = httpConn.getResponseCode();
    UiApplication.getUiApplication().invokeLater(new Runnable() {
        public void run() {
            //Dialog.alert("Response code: " +  Integer.toString(iResponseCode));
        }
    });
} catch (IOException e) {
    System.err.println("Caught IOException: " + e.getMessage());
}

Answer 1

您滥用ConnectionFactory.getConnection(String url, int transportType, String ConnectionUID)方法。例如，检查您传递的内容为transportType ...

以下是关于返回值的API：

返回：如果可以建立连接，则返回ConnectionDescriptor; 否则为null

所以，它只是失败并返回null。这就是你获得NPE的原因。

<强>更新：

我建议您只使用更简单的API ConnectionFactory.getConnection(String url)：

ConnectionDescriptor cd = connFact.getConnection("http://example.com/login.php");
if (cd == null) {
    // throw an error signalling there is no connectivity right now
}
HttpConnection httpConn = (HttpConnection) cd.getConnection();
// the rest of the code working with httpConn ..

Answer 2

查看链接的答案并验证“登录”程序的实施是否适合您的需求： authentication username password url in blackberry

Blackberry HttpPost空指针异常Java

2 个答案: