android开发技巧与实例

• android studio设置注释模板
• 权限动态申请,比如相机和读写卡权限
• 拍照调用
• 图库调用

settings->Editor->File and Code Templates->Includes - >File Header

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (grantResults[0] != PackageManager.PERMISSION_GRANTED || grantResults[1] != PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
        }
    }

    private boolean requestAllPermissions() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED || ContextCompat.checkSelfPermission(this,
                Manifest.permission.CAMERA)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
                            Manifest.permission.CAMERA},
                    0);
            return false;
        }
        return true;
    }

同时需要在主清单中声明

需要执行上面 权限动态申请 过程

java代码

public static final int TAKE_PHOTO_REQUEST_CODE = 1;


    private void takePhoto() {
        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        // Ensure that there's a camera activity to handle the intent
        if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
            // Create the File where the photo should go
            File photoFile = null;
            try {
                photoFile = createImageFile();
            } catch (IOException ex) {
                Log.e("MainActitity", ex.getMessage(), ex);
                Toast.makeText(OCRActivity.this,
                        "Create Camera temp file failed: " + ex.getMessage(), Toast.LENGTH_SHORT).show();
            }
            // Continue only if the File was successfully created
            if (photoFile != null) {
                Log.i(TAG, "FILEPATH " + getExternalFilesDir("Pictures").getAbsolutePath());
                Uri photoURI = FileProvider.getUriForFile(this,
                        "com.xxx.fileprovider",
                        photoFile);
                currentPhotoPath = photoFile.getAbsolutePath();
                takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
                startActivityForResult(takePictureIntent, TAKE_PHOTO_REQUEST_CODE);
                Log.i(TAG, "startActivityForResult finished");
            }
        }

    }

    private File createImageFile() throws IOException {
        // Create an image file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
        File image = File.createTempFile(
                imageFileName,  
                ".bmp",         
                storageDir      
        );
        return image;
    }

//intent回调
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            switch (requestCode) {
                case TAKE_PHOTO_REQUEST_CODE:
                    if (currentPhotoPath != null) {
                        ExifInterface exif = null;
                        try {
                            exif = new ExifInterface(currentPhotoPath);
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION,
                                ExifInterface.ORIENTATION_UNDEFINED);
                        Log.i(TAG, "rotation " + orientation);
                        Bitmap image = BitmapFactory.decodeFile(currentPhotoPath);
                        ....
                    } else {
                        Log.e(TAG, "currentPhotoPath is null");
                    }
                    break;
                default:
                    break;
            }
        }
    }

主清单中声明内容提供者

需要执行上面 权限动态申请 过程

java代码

public static final int OPEN_GALLERY_REQUEST_CODE = 0;

Intent intent = new Intent(Intent.ACTION_PICK, null);
intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, "image/*");
startActivityForResult(intent, OPEN_GALLERY_REQUEST_CODE);


//intent回调
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            switch (requestCode) {
                case OPEN_GALLERY_REQUEST_CODE:
                    if (data == null) {
                        break;
                    }
                    try {
                        ContentResolver resolver = getContentResolver();
                        Uri uri = data.getData();
                        Bitmap image = MediaStore.Images.Media.getBitmap(resolver, uri);
                        String[] proj = {MediaStore.Images.Media.DATA};
                        Cursor cursor = managedQuery(uri, proj, null, null, null);
                        cursor.moveToFirst();
                        if (image != null) {
                            ivInputImage.setImageBitmap(image);
                        }
                    } catch (IOException e) {
                        Log.e(TAG, e.toString());
                    }
                    break;
                
                default:
                    break;
            }
        }
    }