HttpURLConnection PHP脚本未获取数据

Question

我尝试了许多不同的方法，试图使用HttpURLConnection将数据从我的Android应用程序上传到我的服务器上的PHP脚本，但在服务器上由PHP创建的文件中没有显示任何内容。我成功地使用了HTTPClient，但是我必须切换到使用HttpURLConnection。该应用程序在运行时不会崩溃。我确信我忽略了一些简单的东西。我的PHP脚本运行良好，甚至返回了预期的响应，但是我还没有发现我的Android代码有什么问题。感谢任何帮助。

以下是PHP脚本的开头：

  $data = $_POST["deviceSIG"];

以下是我用于将数据上传到PHP脚本的代码：

// the string deviceSIG is defined elsewhere and has been defined in the class.

private class MyAsyncTask extends AsyncTask<String, Integer, String>{
            @Override
            protected String doInBackground(String... params)           
     try{
                URL url = new URL("http://192.168.10.199/user_script.php");

                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(10000);
                conn.setConnectTimeout(15000);
                conn.setRequestMethod("POST");
                conn.setDoInput(true);
                conn.setDoOutput(true);
                conn.connect();             

                OutputStream outputStream = conn.getOutputStream();
                OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
                writer.write(deviceSIG);
                writer.close();
                outputStream.close();

                // read response
                BufferedReader in = new BufferedReader(
                        new InputStreamReader(conn.getInputStream()));

                String inputLine;
                StringBuffer response = new StringBuffer();
                while ((inputLine = in.readLine()) != null) { response.append(inputLine); }
                in.close();

                result = response.toString();   


                // disconnect
                conn.disconnect();              

} catch (UnsupportedEncodingException e) {
    e.printStackTrace();                
} catch (ClientProtocolException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

return result;  

    }               
//-------------------------------------------------------------------------------

            protected void onProgressUpdate(Integer... progress){
                progBar.setProgress(progress[0]);
            }

//-------------------------------------------------------------------------------
            protected void onPostExecute(String result){
                progBar.setVisibility(View.GONE);

    String rawEcho = result;
    String[] Parts = rawEcho.split("~");
    String echo = Parts[1]; 
    String UIID = "User ID: " + echo;

    try {

    FileOutputStream fOS = openFileOutput("Info.txt", Context.MODE_APPEND);
    fOS.write(newLine.getBytes());
    fOS.write(UIID.getBytes());
    fOS.close();

    } catch (FileNotFoundException e) {
    e.printStackTrace();
    } catch (IOException e) {
    e.printStackTrace();
        }   

            }

Answer 1

Android 6.0建议使用HttpURLConnection来发送HTTP请求，我基于GitHub上的Android菜谱制作了一个示例项目:

https://github.com/xinmeng1/HttpUrlConnectionREST

其中包括发送GET/POST（表单数据或多部分）HTTP请求。如果您需要这本书，我可以发送有关HttpURLConnection用法的章节。

Answer 2

经过大约20天的搜索和测试，我有了一个可行的解决方案。Android和Oracle都应该发布这样一个简单的注释示例，它会为我和其他人节省很多时间。

在这篇文章中，欣蒙为我指出了“请求的标题、内容和格式”的正确方向。

功劳也归于jmort253 on能否解释一下HttpURLConnection的连接过程？因为他的代码和他发布的解释(当然，我修改了他的代码以适应我的项目)。

我现在是一个更好的程序员，因为我花时间试图理解为什么我的原始代码失败了。

以下是我注释的代码，用于将文本字符串发布到我的PHP脚本，我希望它能帮助其他遇到麻烦的人。如果有人认为有充分的证明空间，请发表评论：

在PHP端:

$data = $_POST["values"];  // this gets the encoded and formatted string from the Android app.

在Android方面：

import java.net.HttpURLConnection;


// from another place in my code, I used:
// This calls the AsyncTask class below.
new POSTAsyncTask().execute(); 

//--------------------------------------------------

private class POSTAsyncTask extends AsyncTask<String, Integer, String>{
        //    AsyncTask<Params, Progress, Result>.
        //    Params – the type (Object/primitive) you pass to the AsyncTask from .execute() 
        //    Progress – the type that gets passed to onProgressUpdate()
        //    Result – the type returns from doInBackground()

@Override
protected String doInBackground(String... params) {

String phpPOST = null; // make sure this variable is empty
try {
// deviceSIG is defined in another part of the code, and is a text string of values.
// below, the contents of deviceSIG are encoded and populated into the phpPOST variable for POSTing.
// the LACK of encoding was one reason my previous POST attempts failed.
phpPOST = URLEncoder.encode(deviceSIG, "UTF-8");

} catch (UnsupportedEncodingException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}

try {

// Populate the URL object with the location of the PHP script or web page.
URL url = new URL("http://192.168.10.199/user_script.php");

// This is the point where the connection is opened.
HttpURLConnection connection = (HttpURLConnection) url.openConnection();

// "(true)" here allows the POST action to happen.
connection.setDoOutput(true);

// I will use this to get a string response from the PHP script, using InputStream below.
connection.setDoInput(true); 

// set the request method.
connection.setRequestMethod("POST");

// This is the point where you'll know if the connection was
// successfully established. If an I/O error occurs while creating
// the output stream, you'll see an IOException.
OutputStreamWriter writer = new OutputStreamWriter(
        connection.getOutputStream());

// write the formatted string to the connection.
// "values=" is a variable name that is passed to the PHP script.
// The "=" MUST remain on the Android side, and MUST be removed on the PHP side.
// the LACK of formatting was another reason my previous POST attempts failed.
writer.write("values=" + phpPOST);

// Close the output stream and release any system resources associated with this stream. 
// Only the outputStream is closed at this point, not the actual connection.
writer.close();

//if there is a response code AND that response code is 200 OK, do stuff in the first if block
if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
    // OK

    // otherwise, if any other status code is returned, or no status
    // code is returned, do stuff in the else block
} else {
    // Server returned HTTP error code.
}

//                  Get the string response from my PHP script:
    InputStream responseStream = new 
        BufferedInputStream(connection.getInputStream());

    BufferedReader responseStreamReader = 
        new BufferedReader(new InputStreamReader(responseStream));

    String line = "";
    StringBuilder stringBuilder = new StringBuilder();

    while ((line = responseStreamReader.readLine()) != null) {
        stringBuilder.append(line).append("\n");
    }
    responseStreamReader.close();

    String response = stringBuilder.toString();

//  Close response stream:

    responseStream.close();


result = response.toString();   


// Disconnect the connection:
    connection.disconnect();                    
//--------------------------------

} catch (MalformedURLException e) {
// ...
} catch (IOException e) {
// ...
}               
return result; // when I had this as 'return null;', I would get a NullPointerException in String that equaled the result variable.          
}