我正在创建一个应用程序，当你使用用户名和密码登录时，它会从服务器请求信息。服务器的请求需要时间（15-20秒），同时我想展示一个只有几个字的旋转条。但我尝试了AsyncTask类的许多变体，但我无法使其发挥作用。它可以正常获取信息，但在收到响应之前会冻结屏幕。现在我只有一个实现runnable的新线程。我不确定我需要从代码中的哪里调用AsyncTask。
onClick触发attemptLogin()功能：
public void onClick(View view) {
attemptLogin();
}
在attemptLogin()功能中：
// more code
showProgress(true);
new Thread(new GetServerResponseRunnable()).start();
while (wait) {}
// more code
Runnable是：
public class GetServerResponseRunnable implements Runnable {
@Override
public void run() {
response = getInfo.getTours(mUsername, mPassword);
wait = false;
}
}
正如您所看到的，它从不同的类调用另一个函数。这就是功能：
public String getTours(String username, String password) {
String req = "GETALLDATA";
String retStr = "";
try {
url = getURL(req, username, password);
sendOutputLine(url, "");
retStr = getReturnString();
Log.d(LoginActivity.DEBUG_TAG, "getTours() return: " + retStr);
} catch (Exception e) {
Log.d(LoginActivity.DEBUG_TAG, "programm bommed client: " + e.getMessage());
}
return retStr;
}
我需要帮助，请。我主要想做的是：
response = getInfo.getTours(mUsername, mPassword);
wait = false;
同时展示旋转杆。
感谢
更新：2013年2月13日
我用了这个代码，但我得到了
02-13 09:07:16.142: E/AndroidRuntime(1046): java.lang.NullPointerException
行中：
this.dialog.setMessage(getResources().getString(R.string.login_progress_signing_in));
知道为什么吗？
public class LoginTask extends AsyncTask<Object, Void, String> {
public Context context;
public ProgressDialog dialog;
public void BaseTask(Context context) {
this.context = context;
this.dialog = new ProgressDialog(context);
}
@Override
protected void onPreExecute() {
this.dialog.setMessage(getResources().getString(R.string.login_progress_signing_in));
this.dialog.show();
}
@Override
protected String doInBackground(Object... objects) {
String name = (String) objects[0];
String password = (String) objects[1];
String response = getInfo.getTours(name , password );
return response;
}
@Override
protected void onPostExecute(String response) {
if (dialog != null && dialog.isShowing())
dialog.dismiss();
LoginActivity.response = response;
// process response as you need
}
}
我想你需要像这个一样的东西
public class LoginTask extends AsyncTask<Object, Void, String> {
public Context context;
public ProgressDialog dialog;
public BaseTask(Context context) {
this.context = context;
this.dialog = new ProgressDialog(context);
}
@Override
protected void onPreExecute() {
this.dialog.setMessage(context.getResources().getString(R.string.loading));
this.dialog.show();
}
@Override
protected String doInBackground(Object... objects) {
String name = (String) objects[0];
String password = (String) objects[1];
String response = getInfo.getTours(name , password );
return response;
}
@Override
protected void onPostExecute(String response) {
if (dialog != null && dialog.isShowing())
dialog.dismiss();
// process response as you need
}
}
称此为taks
public void onClick(View view) {
new LoginTask(YourActivity.this).execute(name, password);
}
尝试实现android登录活动。在您的ADT中，在create new activity下选择：login activity这将为您生成以下模板代码：
/**
* Activity which displays a login screen to the user, offering registration as
* well.
*/
public class LoginActivityTest extends Activity {
/**
* A dummy authentication store containing known user names and passwords.
* TODO: remove after connecting to a real authentication system.
*/
private static final String[] DUMMY_CREDENTIALS = new String[] {
"foo@example.com:hello", "bar@example.com:world" };
/**
* The default email to populate the email field with.
*/
public static final String EXTRA_EMAIL = "com.example.android.authenticatordemo.extra.EMAIL";
/**
* Keep track of the login task to ensure we can cancel it if requested.
*/
private UserLoginTask mAuthTask = null;
// Values for email and password at the time of the login attempt.
private String mEmail;
private String mPassword;
// UI references.
private EditText mEmailView;
private EditText mPasswordView;
private View mLoginFormView;
private View mLoginStatusView;
private TextView mLoginStatusMessageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login_activity_test);
// Set up the login form.
mEmail = getIntent().getStringExtra(EXTRA_EMAIL);
mEmailView = (EditText) findViewById(R.id.email);
mEmailView.setText(mEmail);
mPasswordView = (EditText) findViewById(R.id.password);
mPasswordView
.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView textView, int id,
KeyEvent keyEvent) {
if (id == R.id.login || id == EditorInfo.IME_NULL) {
attemptLogin();
return true;
}
return false;
}
});
mLoginFormView = findViewById(R.id.login_form);
mLoginStatusView = findViewById(R.id.login_status);
mLoginStatusMessageView = (TextView) findViewById(R.id.login_status_message);
findViewById(R.id.sign_in_button).setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
attemptLogin();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
getMenuInflater().inflate(R.menu.activity_login_activity_test, menu);
return true;
}
/**
* Attempts to sign in or register the account specified by the login form.
* If there are form errors (invalid email, missing fields, etc.), the
* errors are presented and no actual login attempt is made.
*/
public void attemptLogin() {
if (mAuthTask != null) {
return;
}
// Reset errors.
mEmailView.setError(null);
mPasswordView.setError(null);
// Store values at the time of the login attempt.
mEmail = mEmailView.getText().toString();
mPassword = mPasswordView.getText().toString();
boolean cancel = false;
View focusView = null;
// Check for a valid password.
if (TextUtils.isEmpty(mPassword)) {
mPasswordView.setError(getString(R.string.error_field_required));
focusView = mPasswordView;
cancel = true;
} else if (mPassword.length() < 4) {
mPasswordView.setError(getString(R.string.error_invalid_password));
focusView = mPasswordView;
cancel = true;
}
// Check for a valid email address.
if (TextUtils.isEmpty(mEmail)) {
mEmailView.setError(getString(R.string.error_field_required));
focusView = mEmailView;
cancel = true;
} else if (!mEmail.contains("@")) {
mEmailView.setError(getString(R.string.error_invalid_email));
focusView = mEmailView;
cancel = true;
}
if (cancel) {
// There was an error; don't attempt login and focus the first
// form field with an error.
focusView.requestFocus();
} else {
// Show a progress spinner, and kick off a background task to
// perform the user login attempt.
mLoginStatusMessageView.setText(R.string.login_progress_signing_in);
showProgress(true);
mAuthTask = new UserLoginTask();
mAuthTask.execute((Void) null);
}
}
/**
* Shows the progress UI and hides the login form.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
private void showProgress(final boolean show) {
// On Honeycomb MR2 we have the ViewPropertyAnimator APIs, which allow
// for very easy animations. If available, use these APIs to fade-in
// the progress spinner.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
int shortAnimTime = getResources().getInteger(
android.R.integer.config_shortAnimTime);
mLoginStatusView.setVisibility(View.VISIBLE);
mLoginStatusView.animate().setDuration(shortAnimTime)
.alpha(show ? 1 : 0)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mLoginStatusView.setVisibility(show ? View.VISIBLE
: View.GONE);
}
});
mLoginFormView.setVisibility(View.VISIBLE);
mLoginFormView.animate().setDuration(shortAnimTime)
.alpha(show ? 0 : 1)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mLoginFormView.setVisibility(show ? View.GONE
: View.VISIBLE);
}
});
} else {
// The ViewPropertyAnimator APIs are not available, so simply show
// and hide the relevant UI components.
mLoginStatusView.setVisibility(show ? View.VISIBLE : View.GONE);
mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
}
}
/**
* Represents an asynchronous login/registration task used to authenticate
* the user.
*/
public class UserLoginTask extends AsyncTask<Void, Void, Boolean> {
@Override
protected Boolean doInBackground(Void... params) {
// TODO: attempt authentication against a network service.
try {
// Simulate network access.
Thread.sleep(2000);
} catch (InterruptedException e) {
return false;
}
for (String credential : DUMMY_CREDENTIALS) {
String[] pieces = credential.split(":");
if (pieces[0].equals(mEmail)) {
// Account exists, return true if the password matches.
return pieces[1].equals(mPassword);
}
}
// TODO: register the new account here.
return true;
}
@Override
protected void onPostExecute(final Boolean success) {
mAuthTask = null;
showProgress(false);
if (success) {
finish();
} else {
mPasswordView
.setError(getString(R.string.error_incorrect_password));
mPasswordView.requestFocus();
}
}
@Override
protected void onCancelled() {
mAuthTask = null;
showProgress(false);
}
}
}
UserLoginTask是您想要进行身份验证的地方。这将允许您在尝试登录时显示一个微调器。"onPostExecute"将是您在验证后移动到下一个活动的地方，或者返回登录屏幕并向用户显示消息，例如无效密码。
请注意，该模板包括在使用服务器进行身份验证时不需要的dummy_credentials，并且它附带了电子邮件和密码textEdits，但您可以将其更改为任何需要的内容。
您需要实现一个扩展AsyncTask的新类，在一个名为doInBackground的函数中完成所有广泛的工作，并使用一些其他常见方法（如onProgressUpdate）将结果发布到UI线程。快速搜索"android asynctask教程"会产生一些好的结果供您学习。
您的AsyncTask可能看起来像这样：
private class DownloadFilesTask extends AsyncTask<Login, Void, Tours> {
protected void onPreExecute(){
//show the dialog here
}
protected Long doInBackground(URL... urls) {
Tours response = getInfo.getTours(Login.mUsername, Login.mPassword);
return response;
}
protected void onPostExecute(Long result) {
//hide the dialog here
}
}
我对你的项目了解不够，无法将其作为一个临时项目，你必须对其进行一些自定义，但总体"方式"与此类似。