安卓如何从Java中的asynctask访问外部类中的公共变量?
我正在编写一个安卓应用程序,它应该在另一个线程中使用httpclient连接到我的Web服务器。我想在asynctask中使用mainactivity类中的变量,以便httpclient可以将这些变量发布到我的服务器。当我在asynctask中使用公共变量时,httppostmethod会发布空值
这是我的更新代码,我现在可以检索asynctask参数,但当我尝试在向服务器发布的帖子中使用它们时,它仍然会发布空字符串。只有当我用硬编码字符串替换变量phostur、pUsername和pPassword时,它才能正常工作并正确发布
public class MainActivity extends ActionBarActivity {
private AlertDialog alertDialog;
public String pHosturl;
public String pUsername;
public String pPassword;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
AlertDialog.Builder Alertbuilder = new AlertDialog.Builder(this);
Alertbuilder.setPositiveButton("Okay", null);
alertDialog = Alertbuilder.create();
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
pHosturl = GetFileContentString("set1.txt");
pPassword = GetFileContentString("set2.txt");
pUsername = GetFileContentString("set3.txt");
//These files are created in another part of the program and they contain a string value
}
public void ViewData(View v){
HttpAsyncTask task = new HttpAsyncTask();
task.execute(pHosturl, pUsername, pPassword);
}
private class HttpAsyncTask extends AsyncTask<String, Boolean, String> {
@Override
protected String doInBackground(String... params) {
String pHosturl = params[0];
String pUsername = params[1];
String pPassword = params[2];
Log.i("MyApp", "url: " + pHosturl + " username: " + pUsername + " password: " + pPassword);
String Response = "";
try {
Log.i("MyApp", "url: " + pHosturl + " username: " + pUsername + " password: " + pPassword);
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost("http://localhost/OnlineApi/GetCookie.aspx");
List<NameValuePair> nameValuePair = new ArrayList<NameValuePair>(3);
nameValuePair.add(new BasicNameValuePair("sessurl", pHosturl));
nameValuePair.add(new BasicNameValuePair("usn", pUsername));
nameValuePair.add(new BasicNameValuePair("pass", pPassword));
Log.i("MyApp", "url: " + pHosturl + " username: " + pUsername + " password: " + pPassword);
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePair));
HttpResponse response = httpClient.execute(httpPost);
HttpEntity responseEntity = response.getEntity();
Response = EntityUtils.toString(responseEntity);
} catch (Exception e) {
}
return Response;
}
@Override
protected void onPostExecute(String s) {
alertDialog.setTitle("Alert");
alertDialog.setMessage(s);
alertDialog.show();
}
}
public String GetFileContentString(String FileName) {
String RetString = "";
try {
InputStream in = openFileInput(FileName);
if (in != null) {
InputStreamReader tmp = new InputStreamReader(in);
BufferedReader reader = new BufferedReader(tmp);
String str;
StringBuilder buf = new StringBuilder();
while ((str = reader.readLine()) != null) {
buf.append(str + "\n");
}
RetString = buf.toString();
in.close();
}
} catch (Exception e) {
RetString = "";
}
return RetString;
}
}
}
# 1 楼答案
标准做法是将它们传递到异步任务的参数中。 看起来你想要这样的东西: