仍然无法通过连接到数据库来运行我的登录应用程序。我应用了 asynctask，但仍然没有运气。请检查一下。提前致谢。首先，当我单击运行按钮时，我会收到此错误。你能帮我检查一下代码并告诉我什么是错的吗？提前致谢。
public class MainActivity extends Activity implements OnClickListener {
EditText etUser, etPass;
Button bLogin;
//Create string variables that will have the input assigned to them
String username, password;
//Create a HTTPClient as the form container
HttpClient httpclient;
//Use HTTP POST method
HttpPost httppost;
//Create an array list for the input data to be sent
ArrayList<NameValuePair> nameValuePairs;
//Create a HTTP Response and HTTP Entity
HttpResponse response;
HttpEntity entity;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initialise();
}
private void initialise() {
etUser = (EditText) findViewById(R.id.etUser);
etPass = (EditText) findViewById(R.id.etPass);
bLogin = (Button) findViewById(R.id.etSubmit);
//Now to set an onClickListener
bLogin.setOnClickListener((android.view.View.OnClickListener) this);
}
public void onClick(View v) {
// This is where we will be working now
new MyAsyncTask().execute();
}//END onClick()
private static String convertStreamToString(InputStream is) {
/*
* To convert the InputStream to String we use the BufferedReader.readLine()
* method. We iterate until the BufferedReader return null which means
* there's no more data to read. Each line will appended to a StringBuilder
* and returned as String.
*/
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}//END convertStreamToString()
private class MyAsyncTask extends AsyncTask<Void, Void, Void>
{
ProgressDialog mProgressDialog;
@Override
protected void onPostExecute(Void result) {
mProgressDialog.dismiss();
}
@Override
protected void onPreExecute() {
mProgressDialog = ProgressDialog.show(MainActivity.this, "Loading...", "Data is Loading...");
}
@Override
protected Void doInBackground(Void... params) {
//Create new default HTTPClient
httpclient = new DefaultHttpClient();
//Create new HTTP POST with URL to php file as parameter
httppost = new HttpPost("http://10.0.2.2/myteamapp/index.php");
//Assign input text to strings
username = etUser.getText().toString();
password = etPass.getText().toString();
//Next block of code needs to be surrounded by try/catch block for it to work
try {
//Create new Array List
nameValuePairs = new ArrayList<NameValuePair>(2);
//place them in an array list
nameValuePairs.add(new BasicNameValuePair("user", "username"));
nameValuePairs.add(new BasicNameValuePair("pass", "password"));
//Add array list to http post
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
//assign executed form container to response
response = httpclient.execute(httppost); //response from the PHP file
//check status code, need to check status code 200
if(response.getStatusLine().getStatusCode() == 200){
//assign response entity to http entity
entity = response.getEntity();
//check if entity is not null
if(entity != null){
//Create new input stream with received data assigned
InputStream instream = entity.getContent();
//Create new JSON Object. assign converted data as parameter.
JSONObject jsonResponse = new JSONObject(convertStreamToString(instream));
//assign json responses to local strings
String retUser = jsonResponse.getString("user");//mySQL table field
String retPass = jsonResponse.getString("pass");
//Validate login
if(username.equals(retUser)&& password.equals(retPass)){ //Check whether 'retUser' and 'retPass' matches username/password
//Display a Toast saying login was a success
Toast.makeText(getBaseContext(), "Successful", Toast.LENGTH_SHORT).show();
} else {
//Display a Toast saying it failed.
Toast.makeText(getBaseContext(), "Invalid Login Details", Toast.LENGTH_SHORT).show();
}
}
}
} catch(Exception e){
// e.printStackTrace();
//Display toast when there is a connection error
//Change message to something more friendly
Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_SHORT).show();
Toast.makeText(getBaseContext(), "Connection Error", Toast.LENGTH_SHORT).show();
return null;
}
return null;
}
}
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
}