android - 请解释如何使用带有 SQLite db 和 listview 的适配器

Question

在 Android 文档中，关于如何执行此操作的说明相互矛盾。我需要将本地 sqlite db 中的数据连接到ListView布局中的 a，并且我需要能够添加新项目并更新一行（例如按下时删除）。SimpleCursorAdapter现已贬值，建议LoaderManager与CursorLoader. 如果我LoaderManager与 a 一起使用，CursorLoader是否需要创建内容提供者？

Answer 1

看看Commonsware 的 LoaderEx。它提供了SQLiteCursorLoader专门设计用于允许直接通过 Loaders 使用 SQLite，而无需创建 ContentProvider。

Answer 2

希望这件事有所帮助。我已经使用列表行中的图标实现了罢工。

public class Home extends Activity {

ListView lv_home;
Cursor cursor;
static SQLiteDatabase database;
ArrayList<Task> al_task;
ArrayAdapter<Task> aa_task;
ImageView iv_big_add, iv_small_add;
LinearLayout ll;

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

    iv_big_add = (ImageView) findViewById(R.id.imageViewHomeAddBig);
    iv_big_add.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            finish();
            startActivity(new Intent(Home.this, AddTask.class));
        }
    });

    ll = (LinearLayout) findViewById(R.id.linearLayoutHomeNote);

    iv_small_add = (ImageView) findViewById(R.id.imageViewHomeAddSmall);
    iv_small_add.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            finish();
            startActivity(new Intent(Home.this, AddTask.class));
        }
    });

    loadDatabase();

    cursor = database.query("task_info", new String[] { "task_id",
            "task_brief", "task_priority", "is_completed" }, null, null,
            null, null, null);
    if (cursor.getCount() == 0) {
        iv_big_add.setVisibility(View.VISIBLE);
        ll.setVisibility(View.VISIBLE);
        iv_small_add.setVisibility(View.INVISIBLE);
        cursor.close();

    } else {
        iv_big_add.setVisibility(View.INVISIBLE);
        ll.setVisibility(View.INVISIBLE);
        iv_small_add.setVisibility(View.VISIBLE);
        build_listview(cursor);
        cursor.close();

        lv_home = (ListView) findViewById(R.id.listViewHome);
        lv_home.setAdapter(aa_task);
        lv_home.setVisibility(View.VISIBLE);
        lv_home.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {
                // TODO Auto-generated method stub

                Task task = (Task) lv_home.getItemAtPosition(arg2);
                int task_id = task.get_task_id();

                startActivity(new Intent(Home.this, TaskDetails.class).putExtra("task_id", task_id));
                finish();
            }
        });
    }
}

public void build_listview(Cursor tmp_cursor) {
    // TODO Auto-generated method stub

    al_task = new ArrayList<Task>();
    while (tmp_cursor.moveToNext())
    {
        al_task.add(new Task(tmp_cursor.getInt(0), tmp_cursor.getString(1), tmp_cursor.getString(2), tmp_cursor.getString(3)));
    }
    tmp_cursor.close();

    aa_task = new TaskAdapter(this, al_task);
}

void loadDatabase() {
    database = openOrCreateDatabase("ToDoDatabase.db",
            SQLiteDatabase.OPEN_READWRITE, null);
}

static class Task {

    int task_id;
    String task_brief;
    String task_priority;
    String is_completed = "false";

    Task(int tmp_task_id, String tmp_task_brief, String tmp_task_priority,
            String tmp_task_is_completed) {
        task_id = tmp_task_id;
        task_brief = tmp_task_brief;
        task_priority = tmp_task_priority;
        is_completed = tmp_task_is_completed;
    }

    int get_task_id() {
        return task_id;
    }

    String get_task_brief() {
        return task_brief;
    }

    String get_task_priority() {
        return task_priority;
    }

    String get_task_is_completed() {
        return is_completed;
    }

    void set_task_is_completed(String tmp_task_is_completed) {
        is_completed = tmp_task_is_completed;
    }
}

static class TaskViewHolder {

    TextView tv_task_brief;
    ImageView iv_task_is_completed;

    public TaskViewHolder(TextView tmp_tv_task_brief,
            ImageView tmp_iv_task_is_completed) {
        tv_task_brief = tmp_tv_task_brief;
        iv_task_is_completed = tmp_iv_task_is_completed;
    }

    TextView get_tv_task_brief() {
        return tv_task_brief;
    }

    ImageView get_iv_task_is_completed() {
        return iv_task_is_completed;
    }
}

static class TaskAdapter extends ArrayAdapter<Task> {

    LayoutInflater inflater;

    public TaskAdapter(Context context, List<Task> tmp_al_task) {
        super(context, R.layout.single_row_home,
                R.id.textViewSingleRowHome, tmp_al_task);
        inflater = LayoutInflater.from(context);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub

        Task task = (Task) this.getItem(position);

        final ImageView imageView;
        final TextView textView;

        if (convertView == null) {

            convertView = inflater.inflate(R.layout.single_row_home, null);

            imageView = (ImageView) convertView
                    .findViewById(R.id.imageViewSingleRowHome);
            textView = (TextView) convertView
                    .findViewById(R.id.textViewSingleRowHome);

            convertView.setTag(new TaskViewHolder(textView, imageView));

        } else {

            TaskViewHolder viewHolder = (TaskViewHolder) convertView
                    .getTag();
            imageView = viewHolder.get_iv_task_is_completed();
            textView = viewHolder.get_tv_task_brief();
        }

        imageView.setTag(task);

        textView.setText(task.get_task_brief());
        if(task.get_task_priority().equals("High"))
            textView.setTextColor(Color.RED);
        else if(task.get_task_priority().equals("Medium"))
            textView.setTextColor(Color.GREEN);
        else
            textView.setTextColor(Color.BLUE);

        if (task.get_task_is_completed().equals("true")) {

            imageView.setImageResource(R.drawable.action_cancel_icon);
            textView.setPaintFlags(textView.getPaintFlags()
                    | Paint.STRIKE_THRU_TEXT_FLAG);
        } else {

            imageView.setImageResource(R.drawable.action_cancel_icon_2);
            textView.setPaintFlags( textView.getPaintFlags() & (~ Paint.STRIKE_THRU_TEXT_FLAG));
        }

        imageView.setFocusable(false);
        imageView.setFocusableInTouchMode(false);
        imageView.setClickable(true);
        imageView.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {

                Task task = (Task) imageView.getTag();

                if (task.get_task_is_completed().equals("false")) {


                    imageView.setImageResource(R.drawable.action_cancel_icon);

                    ContentValues values = new ContentValues();
                    values.put("is_completed", "true");

                    database.update("task_info", values, "task_id=?",
                            new String[] { task.get_task_id() + "" });
                    values.clear();

                    textView.setPaintFlags(textView.getPaintFlags()
                            | Paint.STRIKE_THRU_TEXT_FLAG);

                    task.set_task_is_completed("true");

                } else {

                    imageView.setImageResource(R.drawable.action_cancel_icon_2);

                    ContentValues values = new ContentValues();
                    values.put("is_completed", "false");

                    database.update("task_info", values, "task_id=?",
                            new String[] { task.get_task_id() + "" });
                    values.clear();

                    textView.setPaintFlags( textView.getPaintFlags() & (~ Paint.STRIKE_THRU_TEXT_FLAG));

                    task.set_task_is_completed("false");
                }
            }
        });

        return convertView;
    }
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {

        showExitDialog();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

private void showExitDialog() {
    // TODO Auto-generated method stub

    AlertDialog.Builder adb = new Builder(Home.this);
    adb.setTitle("Warning");
    adb.setMessage("Are you sure you want to quit ?");
    adb.setIcon(R.drawable.ic_launcher);
    adb.setPositiveButton("Yes", new DialogInterface.OnClickListener() {

        public void onClick(DialogInterface arg0, int arg1) {

            if (database.isOpen())
                database.close();
            finish();
        }
    });

    adb.setNegativeButton("No", new DialogInterface.OnClickListener() {

        public void onClick(DialogInterface arg0, int arg1) {

            arg0.dismiss();
        }
    });

    AlertDialog ad = adb.create();
    ad.show();
}
}