活动从相机活动中返回后丢失数据

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    // 保存关键数据
    outState.putString("key", "value");
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // 恢复数据
    String value = savedInstanceState.getString("key");
}

public class MyViewModel extends ViewModel {
    private MutableLiveData<String> data = new MutableLiveData<>();

    public LiveData<String> getData() {
        return data;
    }

    public void setData(String value) {
        data.setValue(value);
    }
}

public class MainActivity extends AppCompatActivity {
    private MyViewModel viewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        viewModel = new ViewModelProvider(this).get(MyViewModel.class);
        viewModel.getData().observe(this, new Observer<String>() {
            @Override
            public void onChanged(String value) {
                // 更新UI
            }
        });
    }
}

// 使用SharedPreferences保存数据
SharedPreferences sharedPreferences = getSharedPreferences("MyPrefs", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("key", "value");
editor.apply();

// 读取数据
String value = sharedPreferences.getString("key", "default_value");