Question

我知道运行时权限，我已经考虑到了这一点，但它仍然不起作用。我已将这些行添加到清单中：

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

这是我的 onCreate 方法：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_new);
    if (shouldAskPermissions()) {
        askPermissions();
    }
    generateNoteOnSD(this,fileName,msg);
    readFile(fileName);
}

这是询问和授予权限

protected static boolean shouldAskPermissions() {
    return (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP_MR1);
}

@TargetApi(23)
protected void askPermissions() {
    String[] permissions = {
            "android.permission.READ_EXTERNAL_STORAGE",
            "android.permission.WRITE_EXTERNAL_STORAGE"
    };
  /*  int requestCode = 200;
    requestPermissions(permissions, requestCode);*/
    // Check if we have write permission
    int permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        // We don't have permission so prompt the user
        ActivityCompat.requestPermissions(
                this, permissions, 1);
    }
}

这些是写作和阅读方法

 public static void generateNoteOnSD(Context context, String sFileName, String sBody) {
        try {
            File root = new File(String.valueOf(Environment.getExternalStorageDirectory()));
            Log.e("file path is ", String.valueOf(Environment.getExternalStorageDirectory()));
            if (!root.exists()) {
                root.mkdirs();
            }
            File gpxfile = new File(root, sFileName);
            String separator = System.getProperty("line.separator");

            FileWriter writer = new FileWriter(gpxfile.getAbsoluteFile(), true);
            writer.append(separator); // this will add new line ;

            //FileWriter writer = new FileWriter(gpxfile);
            writer.append(sBody);
            writer.flush();
            writer.close();
            Toast.makeText(context, "Saved", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public void readFile(String file1){
        //Find the directory for the SD Card using the API
//*Don't* hardcode "/sdcard"
        File sdcard = Environment.getExternalStorageDirectory();

//Get the text file
        File file = new File(sdcard,file1);

//Read text from file
        StringBuilder text = new StringBuilder();

        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
            String line;

            while ((line = br.readLine()) != null) {
                text.append(line);
                text.append('\n');
            }
            br.close();
        }
        catch (IOException e) {
            //You'll need to add proper error handling here
        }

//Find the view by its id
        Log.e("text",text.toString());
    }

修改这是我的堆栈跟踪：

W/System.err: java.io.FileNotFoundException: /storage/emulated/0/CrowdSensingData: open failed: EACCES (Permission denied)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:487)
W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:87)
W/System.err:     at java.io.FileWriter.<init>(FileWriter.java:58)
W/System.err:     at enis.example.com.alarmmanagertest.FileAndServerHandlingActivity.generateNoteOnSD(FileAndServerHandlingActivity.java:128)
W/System.err:     at enis.example.com.alarmmanagertest.ActivityRecognitionService.handleDetectedActivities(ActivityRecognitionService.java:107)
W/System.err:     at enis.example.com.alarmmanagertest.ActivityRecognitionService.onStart(ActivityRecognitionService.java:122)
W/System.err:     at android.app.Service.onStartCommand(Service.java:459)
W/System.err:     at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3209)
W/System.err:     at android.app.ActivityThread.-wrap17(ActivityThread.java)
W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1586)
W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:111)
W/System.err:     at android.os.Looper.loop(Looper.java:207)
W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5728)
W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
W/System.err: Caused by: android.system.ErrnoException: open failed: EACCES (Permission denied)
W/System.err:     at libcore.io.Posix.open(Native Method)
W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:473)

Answer 1

如果尚未授予权限，则不应立即调用需要它们的方法。而是在onRequestPermissionsResult中调用它们。这保证了只有在用户授予权限后才会执行它们。

if (shouldAskPermissions()) {
    askPermissions();
} else {
    generateNoteOnSD(this,fileName,msg);
    readFile(fileName);
}

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                generateNoteOnSD(this,fileName,msg);
                readFile(fileName);
            } 
        }
    }
}

修改此外，在您的shouldAskPermissions（）方法中包含SO answer Datatables “footerCallback” function not displaying results in footer。

编辑2： 这是shouldAskPermissions（）
的实现
protected boolean shouldAskPermissions() { if(Build.VERSION.SDK_INT <= Build.VERSION_CODES.LOLLIPOP_MR1) { return false; } int permission = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE); return (permission != PackageManager.PERMISSION_GRANTED); }

开放失败：EACCES（权限被拒绝）api23？

1 个答案: