我正在尝试创建一个本机登录屏幕，其中用户名和密码框在处理请求时滑出屏幕（如果登录不成功，则滑回屏幕）。
为了实现这一点，我定义了我的动画 ( DropDownAnimation) 并将其分配给我的LinearLayout(页脚)。当用户单击登录按钮时，我启动动画，然后调用一个函数 ( tryLogin())，该函数启动一个AsyncTask. AsyncTask处理创建和发送登录请求以及获取JSONObject响应的所有工作。
但是，我的问题是slideDown动画直到完成后才开始AsyncTask。这在成功登录时看起来并没有那么糟糕，但在登录失败时，这意味着LinearLayout永远不会向下滑动 - 它会跳到屏幕底部，开始slideUp动画回到原来的位置。
这似乎是与这个问题类似的问题，但我没有使用，而且我bindService()所有的非 UI 代码（对我而言）似乎都包含在其中AsyncTask。LogCat 告诉我：
06-24 04:37:35.141: I/Choreographer(5347): Skipped 137 frames! The application may be doing too much work on its main thread.
我假设那些是页脚会向下滑动的帧 - 但我无法弄清楚我在主线程上执行的东西在哪里。这是我的 LoginPage 和 LoginTask 代码。
登录页面.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login_page);
login = (Button) findViewById(R.id.login);
username = (EditText) findViewById(R.id.username);
password = (EditText) findViewById(R.id.password);
footer = (LinearLayout) findViewById(R.id.footer);
// We must wait for the layout to be finalised before trying to find heights.
ViewTreeObserver vto = footer.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
initAnimations();
}
});
loading = (TextView) findViewById(R.id.loading);
login.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String mUsername = username.getText().toString();
String mPassword = password.getText().toString();
// Neither of these two things happen until after LoginTask is done.
footer.startAnimation(slideDown);
loading.setVisibility(TextView.VISIBLE);
tryLogin(mUsername, mPassword);
}
});
}
protected void tryLogin(String mUsername, String mPassword) {
Exception e;
String loginUrl = getString(R.string.login_url);
String clientId = getString(R.string.client_id);
String clientSecret = getString(R.string.client_secret);
LoginTask loginTask = (LoginTask) new LoginTask().execute(mUsername, mPassword, loginUrl, clientId, clientSecret);
if ((e = loginTask.getException()) != null) {
Toast.makeText(this, e.toString(), Toast.LENGTH_LONG).show();
Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
} else {
JSONObject response;
try {
response = loginTask.get();
Log.d("login", response.toString());
if (!response.has("access_token")) {
loading.setVisibility(TextView.INVISIBLE);
footer.startAnimation(slideUp);
Toast.makeText(this, "Login error", Toast.LENGTH_LONG).show();
} else {
Intent i = new Intent(this, FullscreenWebView.class);
i.putExtra("accessToken", response.get("access_token").toString());
startActivity(i);
overridePendingTransition(0, 0);
}
} catch (InterruptedException e1) {
e1.printStackTrace();
Thread.currentThread().interrupt();
} catch (ExecutionException e1) {
e1.printStackTrace();
} catch (JSONException e1) {
e1.printStackTrace();
throw new RuntimeException(e);
}
}
}
登录任务.java
class LoginTask extends AsyncTask<String, Void, JSONObject> {
private Exception exception;
@Override
protected JSONObject doInBackground(String... params) {
HttpURLConnection connection;
OutputStreamWriter request = null;
URL url = null;
JSONObject response = null;
String parameters = "grant_type=password&username="+params[0]+"&password="+params[1]+"&client_id="+params[3]+"&client_secret="+params[4];
try {
url = new URL(params[2]);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");
request = new OutputStreamWriter(connection.getOutputStream());
request.write(parameters);
request.flush();
request.close();
// username or password is probably wrong
Log.d("login", ""+connection.getResponseCode());
if (connection.getResponseCode() != 200) {
return new JSONObject();
}
String line = "";
InputStreamReader isr = new InputStreamReader(connection.getInputStream());
BufferedReader reader = new BufferedReader(isr);
StringBuilder sb = new StringBuilder();
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
Log.d("login", sb.toString());
response = new JSONObject(sb.toString());
isr.close();
reader.close();
} catch (Exception e) {
this.exception = e;
}
return response;
}
}
我也尝试过成为LoginTask的成员类LoginPage，并在方法中启动动画onPreExecute()，但这并没有改变任何东西。
任何帮助深表感谢！