android开发技巧与实例

Posted 2022-12-11 狂奔的CD

文章目录

• 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

2021/10/14

android studio设置注释模板

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

/**
  *
  * @Classname:      $NAME
  * @Description:    类描述
  * @Author:         xxx
  * @CreateDate:     $DATE $TIME
 */

权限动态申请,比如相机和读写卡权限

/** request permissions
     * 拍照权限和读写卡权限需要在主清单文件中配置
     */
    @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

<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"/>

拍照调用

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;

/**
     * 拍照保存在应用内部
     * 需要在主清单文件中声明对应内容提供者provider   com.xxx.fileprovider
     */
    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,  /* prefix */
                ".bmp",         /* suffix */
                storageDir      /* directory */
        );
        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

 <!--用于拍照存储图片-->
        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="com.xxx.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths"></meta-data>
        </provider>

图库调用

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;