Android显示相册图片和相机拍照

首先看最重要的MainActive类：

public class MainActivity extends AppCompatActivity {

    private final int FROM_ALBUM = 1;//表示从相册获取照片
    private final int FROM_CAMERA = 2;//表示从相机获取照片
    private ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        textView = (TextView)findViewById(R.id.textView);
        setContentView(R.layout.activity_main);

        applyWritePermission();//请求权限

    }

    // 打开相册
    public void onClickAlbum(View view){
        Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
        startActivityForResult(intent, FROM_ALBUM);
    }

    // 打开相机
    public void onClickCamera(View view){
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        startActivityForResult(intent, FROM_CAMERA);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data){

        //从相册返回
        if(requestCode == FROM_ALBUM  &&  resultCode == Activity.RESULT_OK  &&  data != null){
            imageView = (ImageView)findViewById(R.id.imageView);
            textView = (TextView)findViewById(R.id.textView);
            Uri imageUri = data.getData();
            ContentResolver cr = this.getContentResolver();
            try {
                Bitmap bitmap = BitmapFactory.decodeStream(cr.openInputStream(imageUri));

                int res = FaceClassified.runClassified(bitmap);

                imageView.setImageBitmap(bitmap);
            }catch (FileNotFoundException e){
                Log.e("Exception", e.getMessage(), e);
            }
        }

        //从相机返回
        if(requestCode == FROM_CAMERA  &&  resultCode == Activity.RESULT_OK  &&  data != null){
            imageView = (ImageView)findViewById(R.id.imageView);
            textView = (TextView)findViewById(R.id.textView);

            Bitmap photo = (Bitmap) data.getExtras().get("data");

            int res = FaceClassified.runClassified(photo);

            imageView.setImageBitmap(photo);
        }

        super.onActivityResult(requestCode, resultCode, data);
    }

    private void applyWritePermission() {

        String permissions1 = Manifest.permission.WRITE_EXTERNAL_STORAGE;
        String permissions2 = Manifest.permission.READ_EXTERNAL_STORAGE;
        String permissions3 = Manifest.permission.CAMERA;

        if (Build.VERSION.SDK_INT >= 23) {
            int check1 = ContextCompat.checkSelfPermission(this, permissions1);
            if (check1 != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
            }
            int check2 = ContextCompat.checkSelfPermission(this, permissions2);
            if (check2 != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
            }
            int check3 = ContextCompat.checkSelfPermission(this, permissions3);
            if (check3 != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(new String[]{Manifest.permission.CAMERA}, 1);
            }
        }
    }
}

上面两个按钮的处理函数名称在布局中定义，布局如下：两个button（一个打开相册，一个打开相机），一个imageview

 <?xml version="1.0" encoding="utf-8"?>
 <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context="com.meitu.graydemo.MainActivity">

 <LinearLayout
     android:layout_width="368dp"
     android:layout_height="wrap_content"
     android:orientation="vertical"
     tools:layout_editor_absoluteY="0dp"
     tools:layout_editor_absoluteX="8dp">

     <LinearLayout
         android:id="@+id/buttonLayout"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:orientation="horizontal">

         <Button
             android:id="@+id/button"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:onClick="onClickAlbum"
             android:text="打开相册"
             tools:layout_editor_absoluteX="16dp"
             tools:layout_editor_absoluteY="16dp" />

         <Button
             android:id="@+id/button2"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:onClick="onClickCamera"
             android:text="打开相机"
             tools:layout_editor_absoluteX="280dp"
             tools:layout_editor_absoluteY="16dp" />
     </LinearLayout>

     <ImageView
         android:id="@+id/imageView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         app:srcCompat="@android:color/holo_blue_bright"
         tools:layout_editor_absoluteX="16dp"
         tools:layout_editor_absoluteY="48dp" />

 </LinearLayout>

 </android.support.constraint.ConstraintLayout>