无法在 android 中创建 XML 文件

Question

我正在创建一个 xml 文件，我想在其中保存来自 app 的数据。但我在 logcat

中收到以下异常

java.io.IOException: open failed: EACCES (Permission denied)
03-02 12:08:40.352 16419-16419/com.example.accurat.application W/System.err:     at java.io.File.createNewFile(File.java:939)
03-02 12:08:40.352 16419-16419/com.example.accurat.application W/System.err:     at com.example.accurat.application.MainActivity.onPermissionGranted(MainActivity.java:192)
03-02 12:08:40.352 16419-16419/com.example.accurat.application W/System.err:     at com.gun0912.tedpermission.TedInstance.onPermissionResult(TedInstance.java:65)
03-02 12:08:40.352 16419-16419/com.example.accurat.application W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
03-02 12:08:40.352 16419-16419/com.example.accurat.application W/System.err:     at com.squareup.otto.EventHandler.handleEvent(EventHandler.java:89)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.squareup.otto.Bus.dispatch(Bus.java:385)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.squareup.otto.Bus.dispatchQueuedEvents(Bus.java:368)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.squareup.otto.Bus.post(Bus.java:337)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.gun0912.tedpermission.busevent.TedBusProvider.post(TedBusProvider.java:49)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.gun0912.tedpermission.TedPermissionActivity.permissionGranted(TedPermissionActivity.java:123)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.gun0912.tedpermission.TedPermissionActivity.checkPermissions(TedPermissionActivity.java:190)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.gun0912.tedpermission.TedPermissionActivity.onCreate(TedPermissionActivity.java:65)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.Activity.performCreate(Activity.java:6270)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1130)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2395)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2506)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.ActivityThread.-wrap11(ActivityThread.java)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1363)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.os.Looper.loop(Looper.java:148)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5491)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err: Caused by: android.system.ErrnoException: open failed: EACCES (Permission denied)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at libcore.io.Posix.open(Native Method)
03-02 12:08:40.353 16419-16419/com.example.accurat.application W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
03-02 12:08:40.354 16419-16419/com.example.accurat.application W/System.err:     at java.io.File.createNewFile(File.java:932)
03-02 12:08:40.354 16419-16419/com.example.accurat.application W/System.err:

在我的清单文件中我有权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

下面是我遇到错误的代码部分

   final PermissionListener ListenerSaveData = new PermissionListener() {
              @Override
              public void onPermissionGranted() {
                  if(refr_no == "Select a reference number" || meter_type == "Select Meter Type" || Latitude == " " || Longitude == ""
                          || site_status == "Select Site Status" || comm_status == "" || pole_type == "Select pole type" || DateTime == "" )
                  {
                      Toast.makeText(MainActivity.this, " Data not saved.... you must be missing some thing.. Please check!!! " , Toast.LENGTH_LONG ).show();

                  }else {
                      int selectedRadioButton = rg_meter_placement.getCheckedRadioButtonId();
                      rb_meter_placement = (RadioButton)findViewById(selectedRadioButton);
                      Calendar c = Calendar.getInstance();

                      SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                      DateTime = df.format(c.getTime());
                      comm_status = String.valueOf(comment.getText());


                          try {
                              File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + filename);
                              file.createNewFile();
                              FileOutputStream fileos = new FileOutputStream(file);
                              XmlSerializer xmlSerializer = Xml.newSerializer();
                              StringWriter writer = new StringWriter();
                              xmlSerializer.setOutput(writer);
                              xmlSerializer.startDocument("UTF-8", true);
                              xmlSerializer.startTag(null,"record");
                              xmlSerializer.startTag(null,"ref_no");
                              xmlSerializer.text(refr_no);
                              xmlSerializer.endTag(null,"refr_no");
                              xmlSerializer.startTag(null,"meter_type");
                              xmlSerializer.text(meter_type);
                              xmlSerializer.endTag(null,"meter_type");
                              xmlSerializer.startTag(null,"lat");
                              xmlSerializer.text(Latitude);
                              xmlSerializer.endTag(null,"lat");
                              xmlSerializer.startTag(null,"long");
                              xmlSerializer.text(Longitude);
                              xmlSerializer.endTag(null,"long");
                              xmlSerializer.startTag(null,"site_status");
                              xmlSerializer.text(site_status);
                              xmlSerializer.endTag(null,"site_status");
                              xmlSerializer.startTag(null,"communication_status");
                              xmlSerializer.text(comm_status);
                              xmlSerializer.endTag(null,"communication_status");
                              xmlSerializer.startTag(null, "pole_type");
                              xmlSerializer.text(pole_type);
                              xmlSerializer.endTag(null,"pole_type");
                              xmlSerializer.startTag(null,"meter_placement");
                              xmlSerializer.text(String.valueOf(rb_meter_placement));
                              xmlSerializer.endTag(null,"meter_placement");
                              xmlSerializer.startTag(null,"date_time");
                              xmlSerializer.text(DateTime);
                              xmlSerializer.endTag(null,"date_time");
                              xmlSerializer.endTag(null,"record");
                              xmlSerializer.endDocument();
                              xmlSerializer.flush();
                              String dataWrite = writer.toString();
                              fileos.write(dataWrite.getBytes());
                              fileos.close();
                          } catch (FileNotFoundException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                          }
                          catch (IllegalArgumentException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                          }
                          catch (IllegalStateException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                          }
                          catch (IOException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                          }
                      }



              }

              @Override
              public void onPermissionDenied(ArrayList<String> deniedPermissions) {

              }
          };

备注

我知道有很多与此相关的问题，但我找不到更好的解决方案。

更新 1

为了获得许可，我使用 ted 如下

  btn_save_data.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if(refr_no == "Select a reference number" || meter_type == "Select Meter Type" || Latitude == " " || Longitude == ""
                    || site_status == "Select Site Status" || comm_status == "" || pole_type == "Select pole type" || DateTime == "" )
            {
                Toast.makeText(MainActivity.this, " Data not saved.... you must be missing some thing.. Please check!!! " , Toast.LENGTH_LONG ).show();

            }else {

                new TedPermission(MainActivity.this)
                        .setPermissionListener(ListenerSaveData)
                        .setRationaleMessage("This activity will need your permission to save file ")
                        .setPermissions(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                        .check();
              }

        }
    });

非常感谢任何帮助。

Answer 1

您的文件 /storage/emulated/0filename 无法创建，请在文件名和存储位置之间使用“/”

File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/" + filename);
                          file.createNewFile();

Answer 2

您需要为文件创建添加运行时权限

将您的文件相关代码移到单独的方法中，并在授予权限时调用它。

例如：

ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);  //add this code in onCreate()

现在：

if(isPermissionGranted()){
     do_your_work();  //create a method or write the whole code here
    }


 public  boolean isPermissionGranted() {
    if (Build.VERSION.SDK_INT >= 23) {
        if (checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
                == PackageManager.PERMISSION_GRANTED) {
            Log.v(TAG,"Permission is granted");
            return true;
        } else {

            Log.v(TAG,"Permission is revoked");
            ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
            return false;
        }
    }
    else { //permission is automatically granted on sdk<23 upon installation
        Log.v(TAG,"Permission is granted");
        return true;
    }
}


 @Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {

        case 0: {

            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(getContext(), "Permission granted", Toast.LENGTH_SHORT).show();
                //do your work call method
            } else {
                Toast.makeText(getContext(), "Permission denied", Toast.LENGTH_SHORT).show();
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
 }

无法在 android 中创建 XML 文件

Unable to create XML file in android

android

xml

file-access