Spinner數據加載的自定義加載器

如果您想要自定義Spinner的數據加載器，您可以通過擴展AsyncTask類來實現。以下是一個簡單的示例，演示如何使用AsyncTask來加載數據并將其設置到Spinner中：

public class CustomLoader extends AsyncTask<Void, Void, List<String>> {

    private Context mContext;
    private Spinner mSpinner;
    private ProgressDialog mProgressDialog;

    public CustomLoader(Context context, Spinner spinner) {
        mContext = context;
        mSpinner = spinner;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        mProgressDialog = new ProgressDialog(mContext);
        mProgressDialog.setMessage("Loading data...");
        mProgressDialog.show();
    }

    @Override
    protected List<String> doInBackground(Void... voids) {
        // Simulate loading data from a data source (e.g. network request, database query)
        List<String> dataList = new ArrayList<>();
        dataList.add("Item 1");
        dataList.add("Item 2");
        dataList.add("Item 3");
        
        // Simulate a delay for demonstration purposes
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        return dataList;
    }

    @Override
    protected void onPostExecute(List<String> dataList) {
        super.onPostExecute(dataList);
        mProgressDialog.dismiss();

        ArrayAdapter<String> adapter = new ArrayAdapter<>(mContext, android.R.layout.simple_spinner_item, dataList);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        mSpinner.setAdapter(adapter);
    }
}

您可以在Activity或Fragment中調用CustomLoader來加載數據并設置到Spinner中：

Spinner spinner = findViewById(R.id.spinner);
CustomLoader customLoader = new CustomLoader(this, spinner);
customLoader.execute();

請注意，上述示例僅是一個簡單的演示，實際情況中您可能需要根據您的需求進行定制和擴展。您還可以添加錯誤處理、數據緩存、數據過濾等功能來優化您的自定義加載器。