简单说说Android中如何使用摄像头和相册

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>


  
  

  
  

public class MainActivity extends AppCompatActivity {

  private static final String TAG = "MainActivity";

  public static final int OPEN_PHOTO_REQUEST_CODE = 1;
  private Uri imgUrl = null;
  private ImageView imageView;


  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    //为按钮添加【打开摄像头】事件
    findViewById(R.id.open_photo).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        File file = new File(getExternalCacheDir(), "imageView.jpg");//存储照片
        if (file.exists()) {
          file.delete();
        }
        try {
          file.createNewFile();
        } catch (IOException e) {
          e.printStackTrace();
        }


        if (Build.VERSION.SDK_INT >= 24) {//版本高于 7.0
          imgUrl = FileProvider.getUriForFile(MainActivity.this, "net.deniro.camera.fileProvider", file);
        } else {
          imgUrl = Uri.fromFile(file);
        }

        //打开摄像头
        Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imgUrl);//指定图片输出地址
        startActivityForResult(intent, OPEN_PHOTO_REQUEST_CODE);
      }
    });

    //显示拍摄的照片
    imageView = (ImageView) findViewById(R.id.img);


  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    Log.d(TAG, "requestCode: " + requestCode);
    Log.d(TAG, "imgUrl: " + imgUrl);
    switch (requestCode) {
      case OPEN_PHOTO_REQUEST_CODE:
        if (resultCode == RESULT_OK) {
          try {//解析图片并显示
            Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imgUrl));
            imageView.setImageBitmap(bitmap);
          } catch (FileNotFoundException e) {
            e.printStackTrace();
          }
        }
        break;
      default:
        break;
    }
  }
}

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>

  
  
  
  

/**
 * 打开相册请求码
 */
public static final int CHOOSE_PHOTO_REQUEST_CODE = 2;
...
@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  ...
  //打开相册
  findViewById(R.id.choose_photo).setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
      if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
            CHOOSE_PHOTO_REQUEST_CODE);
      } else {
        openAlbum();
      }
    }
});
/**
 * 打开相册
 */
private void openAlbum() {
  Intent intent = new Intent("android.intent.action.GET_CONTENT");
  intent.setType("image/*");
  startActivityForResult(intent, CHOOSE_PHOTO_REQUEST_CODE);
}

/**
 * 请求 WRITE_EXTERNAL_STORAGE 权限
 *
 * 相册中的照片一般是存放在 SD 卡上的，所以从 SD 卡中读取照片需要申请权限
 *
 * WRITE_EXTERNAL_STORAGE 表示读写 SD 卡的能力权限
 * @param requestCode
 * @param permissions
 * @param grantResults
 */
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
  switch (requestCode) {
    case CHOOSE_PHOTO_REQUEST_CODE:
      if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        openAlbum();
      } else {
        Toast.makeText(this, "被拒绝啦", Toast.LENGTH_SHORT).show();
      }
      break;
    default:
      break;
  }
  super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  Log.d(TAG, "requestCode: " + requestCode);
  Log.d(TAG, "imgUrl: " + imgUrl);
  switch (requestCode) {
    case OPEN_PHOTO_REQUEST_CODE:
      if (resultCode == RESULT_OK) {
        try {//解析图片并显示
          Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imgUrl));
          imageView.setImageBitmap(bitmap);
        } catch (FileNotFoundException e) {
          e.printStackTrace();
        }
      }
      break;
    case CHOOSE_PHOTO_REQUEST_CODE:
      if (Build.VERSION.SDK_INT >= 19) {//4.4 及以上系统
        handleFor4_4(data);
      } else {
        handleForBefore4_4(data);
      }
      break;
    default:
      break;
  }
}

/**
 * 处理相片
 * android 4.4-
 *
 * @param data
 */
private void handleForBefore4_4(Intent data) {
  display(getImagePath(data.getData(),null));
}

/**
 * 处理相片
 * android 4.4+
 *
 * @param data
 */
@RequiresApi(api = Build.VERSION_CODES.KITKAT)
private void handleFor4_4(Intent data) {
  String imagePath = null;
  Uri uri = data.getData();//需要解析
  if (DocumentsContract.isDocumentUri(this, uri)) {//是 Document 类型，使用 document id 来处理
    String documentId = DocumentsContract.getDocumentId(uri);
    String mediaDocumentAuthority = "com.android.providers.media.documents";
    String downloadDocumentAuthority = "com.android.providers.downloads.documents";
    if (mediaDocumentAuthority.equals(uri.getAuthority())) {//media 格式
      String id = documentId.split(":")[1];//数字格式的 ID
      String selection = MediaStore.Images.Media._ID + "=" + id;
      imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
    } else if (downloadDocumentAuthority.equals(uri.getAuthority())) {
      Uri cOntentUri= ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(documentId));
      imagePath = getImagePath(contentUri, null);
    }
  } else if ("content".equalsIgnoreCase(uri.getScheme())) {//content 类型 uri
    imagePath = getImagePath(uri, null);
  } else if ("file".equalsIgnoreCase(uri.getScheme())) {//file 类型，则直接获取路径
    imagePath = uri.getPath();
  }
  display(imagePath);
}

/**
 * 显示
 * @param path
 */
private void display(String path) {
  if(path==null){
    Toast.makeText(this, "无法获取图片", Toast.LENGTH_SHORT).show();
  }else{
    imageView.setImageBitmap(BitmapFactory.decodeFile(path));
  }


}

/**
 * 获取图片路径
 *
 * @param uri
 * @param selection
 * @return
 */
private String getImagePath(Uri uri, String selection) {
  String path = null;
  Cursor cursor = getContentResolver().query(uri, null, selection, null, null);
  if (cursor != null) {
    if (cursor.moveToFirst()) {
      path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
    }
    cursor.close();
  }
  return path;
}