将文件上传到服务器，java.net.ProtocolException：读取响应后无法写入请求正文

Question

I want to upload file to server from Android apps. I try this but still cannot upload file to server. There's an error in my java.

public class UploadFileActivity extends AppCompatActivity implements View.OnClickListener{

    private static final int PICK_FILE_REQUEST = 1;
    private static final String TAG = MainActivity.class.getSimpleName();
    private String selectedFilePath;
    private String SERVER_URL = "http://url.com/mobile/json/upload_file.php";
    ImageView ivAttachment;
    Button bUpload;
    TextView tvFileName;
    ProgressDialog dialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_upload_file);
        ivAttachment = (ImageView) findViewById(R.id.ivAttachment);
        bUpload = (Button) findViewById(R.id.b_upload);
        tvFileName = (TextView) findViewById(R.id.tv_file_name);
        ivAttachment.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showFileChooser();
            }
        });
        bUpload.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(selectedFilePath != null){
                    dialog = ProgressDialog.show(UploadFileActivity.this,"","Uploading File...",true);

                    new Thread(new Runnable() {
                        @Override
                        public void run() {
                            uploadFile(selectedFilePath);
                        }
                    }).start();
                }else{
                    Toast.makeText(UploadFileActivity.this,"Please choose a File First",Toast.LENGTH_SHORT).show();
                }
            }
        });
    }


    @Override
    public void onClick(View v) {
    }

    private void showFileChooser() {
        Intent intent = new Intent();
        intent.setType("*/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(Intent.createChooser(intent,"Choose File to Upload.."),PICK_FILE_REQUEST);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode == Activity.RESULT_OK){
            if(requestCode == PICK_FILE_REQUEST){
                if(data == null){
                    //no data present
                    return;
                }


                Uri selectedFileUri = data.getData();
                if(Build.VERSION.SDK_INT >= 19) {
                    selectedFilePath = FilePath.getPath(this, selectedFileUri);
                } else {
                    selectedFilePath = FilePath.getSmartFilePath(this, selectedFileUri);
                }

                Log.i(TAG,"Selected File Path:" + selectedFilePath);

                if(selectedFilePath != null && !selectedFilePath.equals("")){
                    tvFileName.setText(selectedFilePath);
                }else{
                    Toast.makeText(this,"Cannot upload file to server",Toast.LENGTH_SHORT).show();
                }
            }
        }
    }

    public int uploadFile(final String selectedFilePath){

        int serverResponseCode = 0;

        HttpURLConnection connection;
        DataOutputStream dataOutputStream;
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        final String boundary = "*****";


        int bytesRead,bytesAvailable,bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024;
        File selectedFile = new File(selectedFilePath);

        String[] parts = selectedFilePath.split("/");
        String fileName = parts[parts.length-1];
        String[] separate = fileName.split(Pattern.quote("."));
        final String fileNameDoang = separate[0];
        final String fileType = separate[1];

        if (!selectedFile.isFile()){
            dialog.dismiss();

            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    tvFileName.setText("Source File Doesn't Exist: " + selectedFilePath);
                }
            });
            return 0;
        }else{
            try{
                FileInputStream fileInputStream = new FileInputStream(selectedFile);
                URL url = new URL(SERVER_URL);
                connection = (HttpURLConnection) url.openConnection();
                connection.setDoInput(true);//Allow Inputs
                connection.setDoOutput(true);//Allow Outputs
                connection.setUseCaches(false);//Don't use a cached Copy
                connection.setRequestMethod("POST");
                connection.setRequestProperty("Connection", "Keep-Alive");
                connection.setRequestProperty("ENCTYPE", "multipart/form-data");
                connection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
                connection.setRequestProperty("uploaded_file",selectedFilePath);
                int sizeFile = connection.getContentLength();   
                dataOutputStream = new DataOutputStream(connection.getOutputStream());

                dataOutputStream.writeBytes(twoHyphens + boundary + lineEnd);
                dataOutputStream.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                        + selectedFilePath + "\"" + lineEnd);

                dataOutputStream.writeBytes(lineEnd);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable,maxBufferSize);
                buffer = new byte[bufferSize];

                bytesRead = fileInputStream.read(buffer,0,bufferSize);

                while (bytesRead > 0){
                    //write the bytes read from inputstream
                    dataOutputStream.write(buffer,0,bufferSize);
                    bytesAvailable = fileInputStream.available();
                    bufferSize = Math.min(bytesAvailable,maxBufferSize);
                    bytesRead = fileInputStream.read(buffer,0,bufferSize);
                }

                dataOutputStream.writeBytes(lineEnd);
                dataOutputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

                serverResponseCode = connection.getResponseCode();
                String serverResponseMessage = connection.getResponseMessage();

                Log.i(TAG, "Server Response is: " + serverResponseMessage + ": " + serverResponseCode);

                if(serverResponseCode == 200){
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            tvFileName.setText("File Upload completed.\n\n File Name : \n\n" + fileNameDoang + "File Type" + fileType);
                        }
                    });
                }

                fileInputStream.close();
                dataOutputStream.flush();
                dataOutputStream.close();


            } catch (FileNotFoundException e) {
                e.printStackTrace();
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(UploadFileActivity.this,"File Not Found",Toast.LENGTH_SHORT).show();
                    }
                });
            } catch (MalformedURLException e) {
                e.printStackTrace();
                Toast.makeText(UploadFileActivity.this, "URL error!", Toast.LENGTH_SHORT).show();

            } catch (IOException e) {
                e.printStackTrace();
                Toast.makeText(UploadFileActivity.this, "Cannot Read/Write File!", Toast.LENGTH_SHORT).show();
            }
            dialog.dismiss();
            return serverResponseCode;
        }
    }
}

Get filepath I put in another java. This is the warning and error:

09-30 20:44:50.766 9855-10872/com.sintask.android W/System.err: java.net.ProtocolException: cannot write request body after response has been read
09-30 20:44:50.766 9855-10872/com.sintask.android W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:223)
09-30 20:44:50.766 9855-10872/com.sintask.android W/System.err:     at com.sintask.android.ui.UploadFileActivity.uploadFile(UploadFileActivity.java:195)
09-30 20:44:50.766 9855-10872/com.sintask.android W/System.err:     at com.sintask.android.ui.UploadFileActivity$2$1.run(UploadFileActivity.java:66)
09-30 20:44:50.766 9855-10872/com.sintask.android W/System.err:     at java.lang.Thread.run(Thread.java:818)
09-30 20:44:50.766 9855-10872/com.sintask.android E/AndroidRuntime: FATAL EXCEPTION: Thread-5234
                                                                    Process: com.sintask.android, PID: 9855
                                                                    java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
                                                                        at android.os.Handler.<init>(Handler.java:200)

Answer 1

It's because you called getContentLength() before getting the output stream. Doesn't make any sense. You're uploading, not downloading. You don't need the content length, or if you do you don't need it until after you've uploaded the file.

NB available() is not a correct way to determine the length of a file, or of any input stream. Use File.length() .