我是Android新手并学习android。我开发了一个应用程序，通过将图像保存在内部目录中，将摄像头捕获的图像上传到服务器。但是在尝试上传时应用程序停止了。我在这里附上我的代码。如果有人给我的解决方案会更有帮助。
这是我得到的错误：
08-11 16:25:48.638 9100-9438/in.inferon.click_cam E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: in.inferon.click_cam, PID: 9100
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:304)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'char[] java.lang.String.toCharArray()' on a null object reference
at java.io.File.fixSlashes(File.java:185)
at java.io.File.<init>(File.java:134)
at java.io.FileInputStream.<init>(FileInputStream.java:103)
at in.inferon.click_cam.MainActivity$DoFileUpload.doInBackground(MainActivity.java:187)
at in.inferon.click_cam.MainActivity$DoFileUpload.doInBackground(MainActivity.java:170)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
08-11 16:25:48.848 9100-9139/in.inferon.click_cam D/OpenGLRenderer: endAllStagingAnimators on 0xb7c87ce8 (RippleDrawable) with handle 0xb7d2d030
08-11 16:25:49.088 9100-9100/in.inferon.click_cam E/WindowManager: android.view.WindowLeaked: Activity in.inferon.click_cam.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{14806d7c V.E..... R......D 0,0-684,232} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:373)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:271)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:90)
at android.app.Dialog.show(Dialog.java:298)
at in.inferon.click_cam.MainActivity$DoFileUpload.onPreExecute(MainActivity.java:179)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:591)
at android.os.AsyncTask.execute(AsyncTask.java:539)
at in.inferon.click_cam.MainActivity.createImageFile(MainActivity.java:155)
at in.inferon.click_cam.MainActivity.onClick(MainActivity.java:79)
at android.view.View.performClick(View.java:4788)
at android.view.View$PerformClick.run(View.java:19923)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5401)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:919)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:714)
08-11 16:25:50.928 9100-9438/in.inferon.click_cam I/Process: Sending signal. PID: 9100 SIG: 9
这是我的主要课程：
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final int REQUEST_IMAGE_CAPTURE = 101;
Button button_camera, button_save;
private ImageView imageView;
private ConnectionDetector cd;
private Boolean upflag = false;
public Bitmap imageBitmap, bitmapRotate;
File file;
String mCurrentPhotoPath;
private ProgressDialog pDialog;
String imageFileName;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cd = new ConnectionDetector(MainActivity.this);
button_camera = (Button) findViewById(R.id.button_camera);
button_save = (Button) findViewById(R.id.button_save);
imageView = (ImageView) findViewById(R.id.imageView);
cd = new ConnectionDetector(getApplicationContext());
button_camera.setOnClickListener(this);
button_save.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.button_camera:
Intent cameraintent = new Intent(
android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraintent, REQUEST_IMAGE_CAPTURE);
break;
case R.id.button_save:
if (cd.isConnectingToInternet()) {
if (!upflag) {
Toast.makeText(MainActivity.this, "Image Not Captured..!", Toast.LENGTH_LONG).show();
} else {
try {
createImageFile();
} catch (IOException e) {
e.printStackTrace();
}
}
} else {
Toast.makeText(MainActivity.this, "No Internet Connection !", Toast.LENGTH_LONG).show();
}
break;
}
};
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK)
{
Bundle extras = data.getExtras();
Bitmap imageBitmap = (Bitmap) extras.get("data");
imageView.setImageBitmap(imageBitmap);
upflag = true;
}
}
private void createImageFile() throws IOException {
// Create an image file name
// String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
// imageFileName = "JPEG_" + timeStamp + "_";
//File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
//File image = File.createTempFile(
// imageFileName, /* prefix */
// ".jpg", /* suffix */
// storageDir /* directory */
//);
// Save a file: path for use with ACTION_VIEW intents
//mCurrentPhotoPath = image.getAbsolutePath();
ContextWrapper cw = new ContextWrapper(getApplicationContext());
// path to /data/data/yourapp/app_data/imageDir
File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
// Create imageDir
Random generator = new Random();
int n = 10000;
n = generator.nextInt(n);
imageFileName = "null" + n + ".jpg";
File mypath=new File(directory,imageFileName);
FileOutputStream fos = null;
try {
fos = new FileOutputStream(mypath);
// Use the compress method on the BitMap object to write image to the OutputStream
imageBitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
mCurrentPhotoPath= directory.getAbsolutePath();
if (cd.isConnectingToInternet()) {
try {
new DoFileUpload().execute();
}catch (Exception e){
e.printStackTrace();
}
} else {
Toast.makeText(MainActivity.this, "No Internet Connection..", Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
// return image;
}
public class DoFileUpload extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("wait uploading Image..");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected String doInBackground(String... params) {
try {
// Set your file path here
FileInputStream fstrm = new FileInputStream(mCurrentPhotoPath);
// Set your server page url (and the file title/description)
HttpFileUpload hfu = new HttpFileUpload("http://onefind.in/phpuploader/upload_image.php", "ftitle", "fdescription", imageFileName);
upflag = hfu.Send_Now(fstrm);
}
catch (FileNotFoundException e) {
// Error: File not found
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String file_url) {
if (pDialog.isShowing()) {
pDialog.dismiss();
}
if (upflag) {
Toast.makeText(getApplicationContext(), "Uploading Complete", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(getApplicationContext(), "Unfortunately file is not Uploaded..", Toast.LENGTH_LONG).show();
}
}
}
}
public class HttpFileUpload implements Runnable {
URL connectURL;
String responseString;
String Title;
String fileName;
String Description;
byte[ ] dataToServer;
FileInputStream fileInputStream = null;
HttpFileUpload(String urlString, String vTitle, String vDesc, String file){
try{
connectURL = new URL(urlString);
Title= vTitle;
Description = vDesc;
fileName = file;
}catch(Exception ex){
Log.i("HttpFileUpload","URL Malformatted");
}
}
Boolean Send_Now(FileInputStream fStream){
fileInputStream = fStream;
return Sending();
}
Boolean Sending(){
System.out.println("file Name is :"+fileName);
String iFileName = fileName;
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
String Tag="fSnd";
try
{
Log.e(Tag,"Starting Http File Sending to URL");
// Open a HTTP connection to the URL
HttpURLConnection conn = (HttpURLConnection)connectURL.openConnection();
// Allow Inputs
conn.setDoInput(true);
// Allow Outputs
conn.setDoOutput(true);
// Don't use a cached copy.
conn.setUseCaches(false);
// Use a post method.
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary);
DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"title\""+ lineEnd);
dos.writeBytes(lineEnd);
dos.writeBytes(Title);
dos.writeBytes(lineEnd);
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"description\""+ lineEnd);
dos.writeBytes(lineEnd);
dos.writeBytes(Description);
dos.writeBytes(lineEnd);
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + iFileName +"\"" + lineEnd);
dos.writeBytes(lineEnd);
Log.e(Tag,"Headers are written");
// create a buffer of maximum size
int bytesAvailable = fileInputStream.available();
int maxBufferSize = 1024;
int bufferSize = Math.min(bytesAvailable, maxBufferSize);
byte[ ] buffer = new byte[bufferSize];
// read file and write it into form...
int bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0)
{
dos.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable,maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0,bufferSize);
}
dos.writeBytes(lineEnd);
dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
// close streams
fileInputStream.close();
dos.flush();
Log.e(Tag,"File Sent, Response: "+String.valueOf(conn.getResponseCode()));
InputStream is = conn.getInputStream();
// retrieve the response from server
int ch;
StringBuffer b =new StringBuffer();
while( ( ch = is.read() ) != -1 ){ b.append( (char)ch ); }
String s=b.toString();
Log.i("Response",s);
dos.close();
if(String.valueOf(conn.getResponseCode()).equals("200"))
{
return true;
}else{
return false;
}
}
catch (MalformedURLException ex)
{
Log.e(Tag, "URL error: " + ex.getMessage(), ex);
}
catch (IOException ioe)
{
Log.e(Tag, "IO error: " + ioe.getMessage(), ioe);
}
return false;
}
@Override
public void run() {
}
}
public class ConnectionDetector {
private Context _context;
public ConnectionDetector(Context context){
this._context = context;
}
public boolean isConnectingToInternet(){
ConnectivityManager connectivity = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity != null)
{
NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null)
for (int i = 0; i < info.length; i++)
if (info[i].getState() == NetworkInfo.State.CONNECTED)
{
return true;
}
}
return false;
}
@SuppressWarnings("deprecation")
public void showAlertDialog(Context context, String title, String message, Boolean status) {
AlertDialog alertDialog = new AlertDialog.Builder(context).create();
// Setting Dialog Title
alertDialog.setTitle(title);
// Setting Dialog Message
alertDialog.setMessage(message);
// Setting alert dialog icon
// alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);
// Setting OK Button alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
// Showing Alert Message
alertDialog.show();
}
}
答案 0 :(得分：0)
在onClick方法中将代码更改为
case R.id.button_camera:
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
if (isCameraPermissionEnabled()) {
startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
}else {
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.CAMERA},
1);
}
}
同时添加此方法
public boolean isCameraPermissionEnabled() {
return !(Build.VERSION.SDK_INT >= 23 &&
ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED );
}
不要忘记在AndroidManifest.xml中添加权限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />