java - 将文件上传到服务器，java.net.ProtocolException : cannot write request body after response has been read

Question

我想从 Android 应用程序将文件上传到服务器。我尝试了此操作，但仍然无法将文件上传到服务器。我的 java 出现错误。

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;
        }
    }
}

获取我放入另一个java中的文件路径。这是警告和错误:

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

这是因为您在获取输出流之前调用了getContentLength()。没有任何意义。你正在上传，而不是下载。您不需要内容长度，或者如果需要，则在上传文件之后才需要它。

NB available() 不是确定文件或任何输入流长度的正确方法。使用File.length()。