要在Android的RecyclerView中搜索过滤后获取原始项目位置，可以按照以下步骤进行操作：

1. 创建一个适用于RecyclerView的自定义过滤器类，该类扩展了Filter类。在自定义过滤器类中，需要重写两个方法：performFiltering()和publishResults()。

public class CustomFilter extends Filter {
    private List originalList;
    private List filteredList;
    private CustomAdapter adapter;

    public CustomFilter(List originalList, CustomAdapter adapter) {
        this.originalList = originalList;
        this.filteredList = new ArrayList<>();
        this.adapter = adapter;
    }

    @Override
    protected FilterResults performFiltering(CharSequence constraint) {
        filteredList.clear();
        final FilterResults results = new FilterResults();

        if (constraint.length() == 0) {
            filteredList.addAll(originalList);
        } else {
            final String filterPattern = constraint.toString().toLowerCase().trim();

            for (Item item : originalList) {
                if (item.getName().toLowerCase().contains(filterPattern)) {
                    filteredList.add(item);
                }
            }
        }

        results.values = filteredList;
        results.count = filteredList.size();
        return results;
    }

    @Override
    protected void publishResults(CharSequence constraint, FilterResults results) {
        adapter.setFilteredList((List) results.values);
        adapter.notifyDataSetChanged();
    }
}

2. 在RecyclerView的适配器类中添加一个方法来设置过滤后的列表，并保存原始列表和过滤器对象的引用。

public class CustomAdapter extends RecyclerView.Adapter {
    private List originalList;
    private List filteredList;
    private CustomFilter filter;

    public CustomAdapter(List itemList) {
        this.originalList = itemList;
        this.filteredList = itemList;
    }

    public void setFilteredList(List filteredList) {
        this.filteredList = filteredList;
    }

    // 其他方法和实现省略...

    @Override
    public int getItemCount() {
        return filteredList.size();
    }
}

3. 在Activity或Fragment中，初始化RecyclerView和适配器，并为RecyclerView添加一个文本监听器，用于实时监听搜索框的文本变化，然后调用过滤器的filter()方法进行搜索过滤。

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private CustomAdapter adapter;
    private EditText searchEditText;

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

        recyclerView = findViewById(R.id.recyclerView);
        searchEditText = findViewById(R.id.searchEditText);

        List itemList = generateItemList(); // 生成原始项目列表
        adapter = new CustomAdapter(itemList);
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        searchEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
            }

            @Override
            public void afterTextChanged(Editable s) {
                adapter.getFilter().filter(s.toString());
            }
        });
    }
}

通过以上步骤，你可以在Android的RecyclerView中实现搜索过滤，并且获得过滤后项目的原始位置。