安卓展示listview + sql + 异步

 

 

MainActivity内容

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private String mUrl = "https://suggest.taobao.com/sug?code=utf-8&q=%E6%89%8B%E6%9C%BA";
    private Button hq_btn;
    private ListView show_lv;
    private MyAdapter mAdapter;
    private List<List<String>> mList = new ArrayList<>();
    private sqldao sqldao;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        //异步
       
        mAdapter = new MyAdapter(MainActivity.this,mList);
        show_lv.setAdapter(mAdapter);
        show_lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, final int position, long id) {

                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setIcon(R.drawable.ic_launcher_background);
                builder.setTitle("系统提示");
                builder.setMessage("确认要删除吗？");
                builder.setPositiveButton("确认", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        mList.remove(position);
                        mAdapter.notifyDataSetChanged();
                    }
                });
                builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                    }
                });
                AlertDialog creat = builder.create();
                creat.show();
            }
        });
        sqldao  = new sqldao(MainActivity.this);
        if (sqldao.selectData().isEmpty()){
            new MyTask().execute(mUrl);
        }else {
            String json = sqldao.selectData();
            Gson gson = new Gson();
            User user = gson.fromJson(json, User.class);
            mList.addAll(user.getResult());
            mAdapter.notifyDataSetChanged();
        }
       
    }

    private void initView() {
        show_lv = (ListView) findViewById(R.id.show_lv);
    }

    @Override
    public void onClick(View v) {
    }

    //定义一个类继承AsyncTask
    class MyTask extends AsyncTask<String, Void, List<List<String>>> {

        @Override
        protected List<List<String>> doInBackground(String... strings) {
            String data = HttpUtils.getData(strings[0]);
            Gson gson = new Gson();
            User user = gson.fromJson(data, User.class);
            ContentValues contentValues = new ContentValues();
            contentValues.put("json",data);
            sqldao.insertData(contentValues);
            return user.getResult();
        }

        @Override
        protected void onPostExecute(List<List<String>> lists) {
            super.onPostExecute(lists);
            mList.addAll(lists);
            mAdapter.notifyDataSetChanged();
        }
    }

 MyHelper

public class MyHelper extends SQLiteOpenHelper {
    public MyHelper(Context context) {
        super(context, "zhuhuohuo", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table huohuo(json text )");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

SQL Dao

public class sqldao {

    private final SQLiteDatabase db;
    private final MyHelper helper;

    public sqldao(Context context) {
        helper = new MyHelper(context);
        db = helper.getWritableDatabase();
    }

    public String selectData(){
        String jsonStr = "";
        Cursor cursor = db.query("huohuo", null, null, null, null, null, null);
        while (cursor.moveToNext()){
            jsonStr = cursor.getString(cursor.getColumnIndex("json"));
        }
        return jsonStr;
    }
    public  long insertData(ContentValues values) {
        long huohuo = db.insert("huohuo", null, values);
        return huohuo;
    }
}

请求方式

public class Utle {
     public static String you(String mUrl) throws Exception{

         URL url = new URL(mUrl);

         HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

         urlConnection.setRequestMethod("GET");

         urlConnection.setConnectTimeout(5000);

         InputStream stream = urlConnection.getInputStream();

         String inputStr = getInputStr(stream);

         return inputStr;
     }

    public static String getInputStr(InputStream stream) throws IOException {

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stream));

        StringBuffer sb = new StringBuffer();

        String str = null;

        while ((str = bufferedReader.readLine())!=null){

            sb.append(str);

        }

        return sb.toString();
     }
}

适配器

public class MyAdapter extends BaseAdapter {

    private Context mcontext;
    private List<List<String>> mList;

    public MyAdapter(Context mcontext, List<List<String>> mList) {
        this.mcontext = mcontext;
        this.mList = mList;
    }

    @Override
    public int getCount() {
        return mList.size();
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if (convertView==null){
            viewHolder = new ViewHolder();
            convertView = View.inflate(mcontext, R.layout.list_item,null);
            viewHolder.textView = convertView.findViewById(R.id.list_item_tv);
            convertView.setTag(viewHolder);
        }else{
            viewHolder = (ViewHolder) convertView.getTag();
        }
        viewHolder.textView.setText(mList.get(position).toString());
        return convertView;
    }

    class ViewHolder {
        private TextView textView;
    }

}

布局MainActivity

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <ListView
        android:id="@+id/show_lv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/list_item_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>