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我真的被困住了，不知道该怎么办。我已经研究了startActivityForResult内容提供者，但我不知道如何为这个应用程序实现它们中的任何一个。

我没有看到如何从数据库中获取数据并displayBottomList使用相同的更新，listview因此我不必将用户重定向到新的布局/活动。不确定我是否可以调用一个新查询并将其设置为不同的光标并在它们之间切换。我已经看到swapCursor了，但是当使用相同的适配器时它是如何工作的？

ListView当用户单击列表中的一行时，我想用来自 Web 服务调用的新数据进行刷新。我正在使用一个CursorAdapter. 我可以正确获取onClick该行的数据。

我被卡住的地方是如何更新它listView以重新填充数据库/响应中的新信息，而无需将我发送到另一个活动。我希望用户留在同一个屏幕上，但只是listView用新数据更新。

不知道如何让适配器通知适配器在适配器中更新和填充新ListView的onClick，但是ListView在MainActivity.

的适配器BottomListView，我想在单击一行时更新。

public class BottomListViewAdapter extends CursorAdapter {

    private String mEmployeeNumber;
    private EmployeeDBHandler dbHandler;

    public BottomListViewAdapter(Context context, Cursor cursor) {
        super(context, cursor, 0);
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return LayoutInflater.from(context).inflate(R.layout.contact_cardview_layout, parent, false);
    }

    @Override
    public void bindView(View view, final Context context, final Cursor cursor) {
        dbHandler = new EmployeeDBHandler(context);
        ViewHolder holder;
        holder = new ViewHolder();
        holder.tvFirstName = (TextView) view.findViewById(R.id.personFirstName);
        holder.tvLastName = (TextView) view.findViewById(R.id.personLastName);
        holder.tvTitle = (TextView) view.findViewById(R.id.personTitle);
        holder.mPeepPic = (ImageView) view.findViewById(R.id.person_photo);
        holder.mDetailsButton = (ImageButton) view.findViewById(R.id.fullDetailButton);
        holder.mCardView = (CardView) view.findViewById(R.id.home_screen_cardView);

        String mFirstName = cursor.getString(cursor.getColumnIndexOrThrow("First_name"));
        String mLastName = cursor.getString(cursor.getColumnIndexOrThrow("Last_name"));
        String mTitle = cursor.getString(cursor.getColumnIndexOrThrow("Payroll_title"));
        String mThumbnail = cursor.getString(cursor.getColumnIndexOrThrow("ThumbnailData"));

        holder.tvFirstName.setText(mFirstName);
        holder.tvLastName.setText(mLastName);
        holder.tvTitle.setText(mTitle);

        if (mThumbnail != null) {
            byte[] imageAsBytes = Base64.decode(mThumbnail.getBytes(), Base64.DEFAULT);
            Bitmap parsedImage = BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length);
            holder.mPeepPic.setImageBitmap(parsedImage);
        } else {
            holder.mPeepPic.setImageResource(R.drawable.img_place_holder_adapter);
        }

        final int position = cursor.getPosition();

        holder.mDetailsButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cursor.moveToPosition(position);
                String mEmployeeNumber = cursor.getString(1);
                String mEmail = cursor.getString(8);
                String mFirstName = cursor.getString(2);
                String mLastName = cursor.getString(3);
                String mPhoneMobile = cursor.getString(4);
                String mPhoneOffice = cursor.getString(5);
                String mCostCenter = cursor.getString(10);
                String mHasDirectReports = cursor.getString(7);
                String mTitle = cursor.getString(6);
                String mPic = cursor.getString(9);
                Intent mIntent = new Intent(context, EmployeeFullInfo.class);
                mIntent.putExtra("Employee_number", mEmployeeNumber);
                mIntent.putExtra("Email", mEmail);
                mIntent.putExtra("First_name", mFirstName);
                mIntent.putExtra("Last_name", mLastName);
                mIntent.putExtra("Phone_mobile", mPhoneMobile);
                mIntent.putExtra("Phone_office", mPhoneOffice);
                mIntent.putExtra("Cost_center_id", mCostCenter);
                mIntent.putExtra("Has_direct_reports", mHasDirectReports);
                mIntent.putExtra("Payroll_title", mTitle);
                mIntent.putExtra("ThumbnailData", mPic);
                mIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                view.getContext().startActivity(mIntent);
            }
        });

        holder.mCardView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                cursor.moveToPosition(position);
                mEmployeeNumber = cursor.getString(1);
                Toast.makeText(context, mEmployeeNumber, Toast.LENGTH_SHORT).show();
                callNewDirectReport();
                notifyDataSetChanged();

            }
        });
    }

    public static class ViewHolder {
        TextView tvFirstName;
        TextView tvLastName;
        TextView tvTitle;
        ImageView mPeepPic;
        ImageButton mDetailsButton;
        CardView mCardView;
    }

    private void callNewDirectReport() {
        String mDirectReportUrl = "mURL";

        HttpUrl.Builder urlBuilder = HttpUrl.parse(mDirectReportUrl).newBuilder();
        urlBuilder.addQueryParameter("manager_employee_number", mEmployeeNumber);
        String url = urlBuilder.build().toString();


        OkHttpClient client = getUnsafeOkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                    final String responseData = response.body().string();
                    final InputStream stream = new ByteArrayInputStream(responseData.getBytes());
                    final XMLPullParserHandler parserHandler = new XMLPullParserHandler();
                    final ArrayList<Employee> employees = (ArrayList<Employee>) parserHandler.parse(stream);

                    for (Employee e : employees) {
                        dbHandler.addEmployee(e);
                    }
            }
        });
    }

    @Override
    public void notifyDataSetChanged() {
        super.notifyDataSetChanged();
    }
}

我的 MainActivity 正在调用适配器

public class MainActivity extends AppCompatActivity {

    private ProgressBar mProgressBar;
    private BottomListViewAdapter mBottomAdapter;
    private View mDividerView;
    EmployeeDBHandler dbHandler;
    private int mStartingEmployeeID = mStartingID;
    private String table = "employees";
    private static final int LOADER_INTEGER = 1;
    private Cursor mBottomCursor, mTopCursor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
        mDividerView = findViewById(R.id.divider);
        dbHandler = new EmployeeDBHandler(getApplicationContext());
        mProgressBar.setVisibility(View.VISIBLE);
        mDividerView.setVisibility(View.GONE);
        getXMLData();

        //GUI for seeing android SQLite Database in Chrome Dev Tools
        Stetho.InitializerBuilder inBuilder = Stetho.newInitializerBuilder(this);
        inBuilder.enableWebKitInspector(Stetho.defaultInspectorModulesProvider(this));
        Stetho.Initializer in = inBuilder.build();
        Stetho.initialize(in);
    }

    public void getXMLData() {
        OkHttpClient client = getUnsafeOkHttpClient();
        Request request = new Request.Builder()
                .url(getString(R.string.API_FULL_URL))
                .build();
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, final Response response) throws IOException {
                final String responseData = response.body().string();
                final InputStream stream = new ByteArrayInputStream(responseData.getBytes());
                final XMLPullParserHandler parserHandler = new XMLPullParserHandler();
                final ArrayList<Employee> employees = (ArrayList<Employee>) parserHandler.parse(stream);

                for (Employee e : employees) {
                    dbHandler.addEmployee(e);

                }

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        mProgressBar.setVisibility(View.GONE);
                        mDividerView.setVisibility(View.VISIBLE);
                        displayTopList();
                        displayBottomList();
                    }
                });
            }
        });
    }

    public void displayTopList() {
        SQLiteDatabase db = dbHandler.getWritableDatabase();
        mTopCursor = db.rawQuery("SELECT * FROM " + table + " WHERE " + "Employee_number" + "=" + mStartingEmployeeID, null);
        ListView mTopListView = (ListView) findViewById(R.id.mTopList);
        TopListCursorAdapter topAdapter = new TopListCursorAdapter(this, mTopCursor);
        mTopListView.setAdapter(topAdapter);
    }

    public void displayBottomList() {
        SQLiteDatabase db = dbHandler.getWritableDatabase();
        mBottomCursor = db.rawQuery("SELECT * FROM " + table + " WHERE " +
                "Employee_number" + "!=" + mStartingEmployeeID + " AND " +
                "Manager_employee_number" + "=" + mStartingEmployeeID + " ORDER BY " +
                "Last_name" + " ASC", null);

        ListView mBottomListView = (ListView) findViewById(R.id.mDirectReportList);
        mBottomAdapter = new BottomListViewAdapter(this, mBottomCursor);
        mBottomListView.setAdapter(mBottomAdapter);
        mBottomAdapter.notifyDataSetChanged();

    }
}
4

2 回答 2

1

您可以使用 startActivityForResult 从活动接收回调，这里有一个解释如何使用它的教程：https ://developer.android.com/training/basics/intents/result.html

当您在 onActivityResult 中收到回调时，您可以更新数据并调用 notifyDatasetChanged。

您不能从另一个活动中调用代码，因为活动是由 android 处理的。Android 可能已经终止了您尝试调用的活动，并且只会在必要时重新创建它。

于 2017-02-10T16:39:08.813 回答
1

现在，您的代码callNewDirectReport()发出 API 请求并将结果存储在数据库中。这不会更新适配器以显示新项目，而是您需要重新查询数据库并获取更新的光标。以下是您如何执行此操作的示例：

public class BottomListViewAdapter extends CursorAdapter {

    private String mEmployeeNumber;
    private EmployeeDBHandler dbHandler;
    private Activity activityRef;   

    public BottomListViewAdapter(Context context, Cursor cursor) {
        super(context, cursor, 0);
        // keep a reference to the activity
        activityRef = (Activity) context;
    }
        
    //...

    private void callNewDirectReport() {
        //...
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                    final String responseData = response.body().string();
                    final InputStream stream = new ByteArrayInputStream(responseData.getBytes());
                    final XMLPullParserHandler parserHandler = new XMLPullParserHandler();
                    final ArrayList<Employee> employees = (ArrayList<Employee>) parserHandler.parse(stream);

                    for (Employee e : employees) {
                        dbHandler.addEmployee(e);
                    }
                    // the new items are in the database so requery the database to get a new fresher Cursor:
                    SQLiteDatabase db = dbHandler.getWritableDatabase();
                    Cursor fresherCursor = db.rawQuery("SELECT * FROM " + table + " WHERE " +
                        "Employee_number" + "!=" + mStartingEmployeeID + " AND " +
                        "Manager_employee_number" + "=" + mStartingEmployeeID + " ORDER BY " +
                        "Last_name" + " ASC", null);
                    //change the adapter's Cursor
                    activityRef.runOnUiThread(new Runnable() {
                        public void run() {
                            swapCursor(freshedCursor);
                        }
                    });
            }
        });
    }
}
于 2017-02-13T16:59:20.690 回答