android - 异步任务安卓

Question

我有一个登录页面，我想在其中验证来自网络数据库的用户名和密码。问题是在执行 AsyncTask 时我想返回用户名和密码值。但这并没有发生。

如何返回值？这是我的登录页面代码。

public class Login extends Activity {
Integer aaa=0;
Button b,b2;
RelativeLayout r;
TextView t, t2;
String str1, str2, username, password;
String A = null, B = null;
EditText et1, et2;
Dialog myDialog;
String FILENAME = "http://animsinc.com/query.php";
protected ProgressDialog dialog;
protected Handler h;
static InputStream in = null;
static JSONObject jObj = null;
static String json = "";
private static final String TAG_ID = "id";

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.sign_in);

    Display display = ((WindowManager)getSystemService(Context.WINDOW_SERVICE))
            .getDefaultDisplay();
    int width = display.getWidth();
    int height = display.getHeight() / 4;
    r = (RelativeLayout) findViewById(R.id.RL);
    RelativeLayout.LayoutParams r = new RelativeLayout.LayoutParams(width,
            height);
    t = (TextView) findViewById(R.id.textView1);
    t2 = (TextView) findViewById(R.id.textView2);
    t.setOnClickListener(link);
    t2.setOnClickListener(fgtpass);

    et1 = (EditText) findViewById(R.id.editText1);
    et2 = (EditText) findViewById(R.id.editText2);

    b2 = (Button) findViewById(R.id.button2);
    b2.setOnClickListener(temp);

    b = (Button) findViewById(R.id.button1);
    b.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            if ((et1.getText().length() == 0)
                    || (et2.getText().length() == 0))

            {

                Toast.makeText(getApplicationContext(),
                "Please enter correct details",Toast.LENGTH_LONG)
                        .show();

            } else {

                dialog = ProgressDialog.show(Login.this, "Loading",
                        "Please Wait...");

            /*  h = new Handler() {

                    @Override
                    public void handleMessage(Message msg) {
                        super.handleMessage(msg);
                        dialog.dismiss();
                    }
                };

                new Thread() {

                    @Override
                    public void run() {
                        super.run();

                        String st=startDownload();

                        try {
                            Thread.sleep(3000);
                            h.sendEmptyMessage(0);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

                    }

                }.start();*/

     Toast.makeText(getApplicationContext(),""+st,Toast.LENGTH_LONG).show();
        String st=startDownload();
 Toast.makeText(getApplicationContext(),"aaa="+aaa, Toast.LENGTH_LONG).show();
 Toast.makeText(getApplicationContext(),""+st, Toast.LENGTH_LONG).show();
            }
if ((et1.getText().toString().equals(username))&&           (et2.getText().toString().equals(password)))
           {
    Intent openStartingPoint = new Intent(Login.this,
                        UserActivity.class);
                startActivity(openStartingPoint);
            }

        }

    });


}

private 
String startDownload() {
    String C = null;
    new AppTask().execute(FILENAME);
    aaa++;
    return C;
}


private View.OnClickListener temp = new View.OnClickListener() {
    public void onClick(View V) {
        Intent openStartingPoint = new Intent(Login.this,
                UserActivity.class);
        startActivity(openStartingPoint);
    }
};

private View.OnClickListener link = new View.OnClickListener() {
    public void onClick(View V) {
        Intent openStartingPoint = new Intent(Login.this,
                ContactDetails.class);
        startActivity(openStartingPoint);
    }
};

private View.OnClickListener fgtpass = new View.OnClickListener() {
    public void onClick(View V) {
        myDialog = new Dialog(Login.this);
        myDialog.setContentView(R.layout.emailpop);
        myDialog.setTitle("Forgot Password");
        myDialog.setCancelable(true);

        // for save
        Button ok = (Button) myDialog.findViewById(R.id.button1);
        ok.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {

                myDialog.dismiss();

            }
        });
        myDialog.show();
    }
};


@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();

}

public class AppTask extends AsyncTask<String, Integer, String> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        // TODO Auto-generated method stub
        super.onProgressUpdate(values);
    }

    @Override
    protected String doInBackground(String... params) {
        String is = null;
        str1 = et1.getText().toString();
        str2 = et2.getText().toString();

        if (str1.length() > 0 && str2.length() > 0) {
            A = str1;
            B = str2;
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(
                    "http://animsinc.com/query.php");
            try {
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(
                        2);
        nameValuePairs.add(new BasicNameValuePair("username", str1));
        nameValuePairs.add(new BasicNameValuePair("password", str2));
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                httpclient.execute(httppost);

        HttpResponse response = httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                is = EntityUtils.toString(entity);

                JSONArray jArray = new JSONArray(is);

                for (int i = 0; i < jArray.length(); i++) {

            JSONObject jObject = jArray.getJSONObject(i);

                    username = jObject.getString("username");
                    password = jObject.getString("password");
                    aaa++;
                }

            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        } 

        return username;
    }

}

}

Answer 1

@Override
protected void onPostExecute(String result) {
    super.onPostExecute(result);

// result is the value you return from doInBackground     
String username = result;
}