Android调用摄像头拍照以及选择照片

public class MainActivity extends AppCompatActivity {
public static final int TAKE_PHOTO = 1;
public static final int CHOOSE_PHOTO = 2;
private Button mTakePhoto, mChoosePhoto;
private ImageView picture;
private Uri imageUri;

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

mTakePhoto = (Button) findViewById(R.id.btn_take_photo);
mChoosePhoto = (Button) findViewById(R.id.choose_from_album);
picture = (ImageView) findViewById(R.id.iv_picture);

mTakePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//创建file对象，用于存储拍照后的图片；
File outputImage = new File(getExternalCacheDir(), "output_image.jpg");

try {
if (outputImage.exists()) {
outputImage.delete();
}
outputImage.createNewFile();

} catch (Exception e) {
e.printStackTrace();
}

if (Build.VERSION.SDK_INT >= 24) {
imageUri = FileProvider.getUriForFile(MainActivity.this,
"com.gyq.cameraalbumtest.fileprovider", outputImage);
} else {
imageUri = Uri.fromFile(outputImage);
}

//启动相机程序
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent, TAKE_PHOTO);
}
});

mChoosePhoto.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}, 1);
} 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);
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case 1:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
openAlbum();
} else {
Toast.makeText(this, "you denied the permission", Toast.LENGTH_SHORT).show();
}
break;

}
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case TAKE_PHOTO:
if (resultCode == RESULT_OK) {
try {
Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bm);
} catch (Exception e) {
e.printStackTrace();
}

}
break;
case CHOOSE_PHOTO:
if (resultCode == RESULT_OK) {
if (Build.VERSION.SDK_INT >= 19) { //4.4及以上的系统使用这个方法处理图片；
handleImageOnKitKat(data);
} else {
handleImageBeforeKitKat(data); //4.4及以下的系统使用这个方法处理图片
}
}
default:
break;
}
}

private void handleImageBeforeKitKat(Intent data) {
Uri uri = data.getData();
String imagePath = getImagePath(uri, null);
displayImage(imagePath);
}

private String getImagePath(Uri uri, String selection) {
String path = null;
//通过Uri和selection来获取真实的图片路径
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;
}

private void displayImage(String imagePath) {
if (imagePath != null) {
Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
picture.setImageBitmap(bitmap);
} else {
Toast.makeText(this, "failed to get image", Toast.LENGTH_SHORT).show();
}
}

/**
* 4.4及以上的系统使用这个方法处理图片
*
* @param data
*/
@TargetApi(19)
private void handleImageOnKitKat(Intent data) {
String imagePath = null;
Uri uri = data.getData();
if (DocumentsContract.isDocumentUri(this, uri)) {
//如果document类型的Uri,则通过document来处理
String docID = DocumentsContract.getDocumentId(uri);
if ("com.android.providers.media.documents".equals(uri.getAuthority())) {
String id = docID.split(":")[1]; //解析出数字格式的id
String selection = MediaStore.Images.Media._ID + "=" + id;

imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
} else if ("com.android.providers.downloads.documents".equals(uri.getAuthority())) {
Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/piblic_downloads"), Long.valueOf(docID));

imagePath = getImagePath(contentUri, null);

}

} else if ("content".equalsIgnoreCase(uri.getScheme())) {
//如果是content类型的uri，则使用普通方式使用
imagePath = getImagePath(uri, null);
} else if ("file".equalsIgnoreCase(uri.getScheme())) {
//如果是file类型的uri，直接获取路径即可
imagePath = uri.getPath();

}

displayImage(imagePath);
}
}