我需要在自定义列表视图中防止延迟加载。所以我发现scrollview onscroll listner是有帮助的，我已经尝试过但没有成功实现这个功能。
代码：
lviewAdapter = new ListViewAdapter(SaxParser2.this, Arr_ActivityName, Arr_AudioScript,Arr_RequestID,Arr_FolderPath,Arr_RequestTo);
lview.setOnScrollListener(SaxParser2.this);
@Override
public void onScroll(AbsListView arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
lview.setAdapter(lviewAdapter);
}
@Override
public void onScrollStateChanged(AbsListView arg0, int arg1) {
// TODO Auto-generated method stub
}
这是我的BaseAdapter
package com.RecordingApp;
import it.sauronsoftware.ftp4j.FTPClient;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.net.HttpURLConnection;
import java.net.URL;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Typeface;
import android.graphics.drawable.AnimationDrawable;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import android.os.AsyncTask;
import android.os.CountDownTimer;
import android.os.Environment;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.Sharedpreferance.GMailSender;
public class ListViewAdapter extends BaseAdapter {
public static Activity context;
String title[];
String description[];
String RequestId[];
String Folderpath[];
String RequestTo[];
boolean b_Flag_Record_or_not = false;
boolean b_upload_or_not = false;
boolean start_or_not = false;
boolean start_play = false;
boolean upload_or_not = false;
boolean b_play_or_not = false;
boolean isplaying2 = false;
Thread welcomeThread,welcomeThread2;
int glob_position;
MediaPlayer mPlayer2;
int flag_stop_position;
AudioRecorder recorder;
AnimationDrawable frameAnimation, frameAnimation_play;
private static String mFileName = null;
private MediaRecorder mRecorder = null;
private MediaPlayer mPlayer = null;
Recording login = new Recording();
MediaPlayer MP_completeRequest = new MediaPlayer();
public ListViewAdapter(Activity context, String[] title,
String[] description, String[] req_id, String[] FolderPath,
String[] Arr_RequestTo) {
super();
this.context = context;
this.title = title;
this.description = description;
this.RequestId = req_id;
this.Folderpath = FolderPath;
this.RequestTo = Arr_RequestTo;
}
public int getCount() {
// TODO Auto-generated method stub
return title.length;
}
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
private class ViewHolder {
TextView txtViewTitle;
TextView txtViewDescription;
Button record, stop, play, upload;
}
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
final ViewHolder holder;
LayoutInflater inflater = context.getLayoutInflater();
glob_position = position;
if (convertView == null) {
convertView = inflater.inflate(R.layout.listitem_row, null);
holder = new ViewHolder();
holder.txtViewTitle = (TextView) convertView
.findViewById(R.id.textView1);
holder.txtViewDescription = (TextView) convertView
.findViewById(R.id.textView2);
holder.record = (Button) convertView.findViewById(R.id.record);
holder.stop = (Button) convertView.findViewById(R.id.stop);
holder.play = (Button) convertView.findViewById(R.id.play1);
holder.upload = (Button) convertView
.findViewById(R.id.audio_upload);
holder.record.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (isplaying2 == true) {
} else {
if (b_Flag_Record_or_not == true) {
} else {
try {
holder.record.setBackgroundResource(R.drawable.record_green);
b_Flag_Record_or_not = true;
b_play_or_not = true;
flag_stop_position = position;
AuthHandler dataHandler = new AuthHandler();
AuthDataset dataset = dataHandler
.getParsednewJobdtl_DataSet();
// Login l = new Login();
String str_useid = RequestTo[position];
recorder = new AudioRecorder(
"/audiometer/shanesh"
+ RequestId[position] + "-"
+ str_useid);
start_or_not = true;
recorder.start();
Toast.makeText(context, "Recording Started",
Toast.LENGTH_LONG).show();
CountDownTimer countDowntimer = new CountDownTimer(
120000000, 1000) {
public void onTick(long millisUntilFinished) {
}
public void onFinish() {
try {
Toast.makeText(
context,
"Stop recording Automatically ",
Toast.LENGTH_LONG).show();
recorder.stop();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
countDowntimer.start();
} catch (IOException e) {
gotoGmail(e);
} catch (Exception e) {
gotoGmail(e);
}
}
}
}
});
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
try {
Typeface face = Typeface.createFromAsset(context.getAssets(),
"fonts/tahoma.ttf");
holder.txtViewTitle.setTypeface(face);
holder.txtViewTitle.setText(title[position]);
holder.txtViewDescription.setText(description[position]);
} catch (ArrayIndexOutOfBoundsException e) {
e.printStackTrace();
}
holder.stop.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
if (isplaying2 == true) {
mPlayer2.stop();
isplaying2 = false;
} else {
holder.record.setBackgroundResource(R.drawable.page7_15);
if (flag_stop_position == position) {
b_Flag_Record_or_not = false;
if (start_or_not == true) {
b_play_or_not = false;
recorder.stop();
upload_or_not = true;
start_play = true;
Toast.makeText(context, "Stoped Recording",
Toast.LENGTH_LONG).show();
} else {
Toast.makeText(context,
" Please Start recording ",
Toast.LENGTH_LONG).show();
}
} else {
}
}
} catch (Exception e) {
gotoGmail(e);
}
}
});
holder.play.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
String temp = SaxParser2.str_completeORpendingFlag;
if (temp.equalsIgnoreCase("c")) {
try {
final MediaPlayer mPlayer = new MediaPlayer();
try {
mPlayer.setDataSource(Folderpath[position]);
mPlayer.prepare();
final int welcomeScreenDisplay = mPlayer
.getDuration();
welcomeThread = new Thread() {
int wait = 0;
@Override
public void run() {
try {
isplaying2 = true;
mPlayer.start();
while (wait < welcomeScreenDisplay) {
sleep(100);
wait += 100;
}
} catch (Exception e) {
} finally {
isplaying2 = false;
}
}
};
welcomeThread.start();
} catch (Exception e) {
gotoGmail(e);
}
} catch (Exception e) {
gotoGmail(e);
}
} else if (temp.equalsIgnoreCase("p")) {
try {
if (b_play_or_not == true) {
} else {
String str_useid = RequestTo[position];
java.io.File file = new java.io.File(Environment
.getExternalStorageDirectory()
+ "/audiometer/", "shanesh"
+ RequestId[position] + "-" + str_useid
+ ".amr");
if (file.exists()) {
Toast.makeText(context, "Playing",
Toast.LENGTH_LONG).show();
mPlayer2 = new MediaPlayer();
try {
mPlayer2.setDataSource(Environment
.getExternalStorageDirectory()
+ "/audiometer/shanesh"
+ RequestId[position]
+ "-"
+ str_useid + ".amr");
mPlayer2.prepare();
mPlayer2.start();
isplaying2 = true;
final int welcomeScreenDisplay = mPlayer2
.getDuration();
/**
* create a thread to show splash up to
* splash time
*/
welcomeThread = new Thread() {
int wait = 0;
@Override
public void run() {
try {mPlayer2.prepare();
while (wait < welcomeScreenDisplay) {
sleep(100);
wait += 100;
}
} catch (Exception e) {
} finally {
welcomeThread2 = new Thread() {
int wait = 0;
@Override
public void run() {
try {
mPlayer2.start();
while (wait < welcomeScreenDisplay) {
sleep(100);
wait += 100;
}
} catch (Exception e) {
} finally {
// frameAnimation_play.stop();
isplaying2 = false;
}
}
};
welcomeThread2.start();
}
}
};
welcomeThread.start();
} catch (Exception e) {
gotoGmail(e);
}
} else {
Toast.makeText(context, " File Not Found ",
Toast.LENGTH_LONG).show();
}
}
} catch (Exception e) {
gotoGmail(e);
}
}
}
});
holder.upload.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
glob_position = position;
// String str_useid = RequestTo[position];
if (upload_or_not == true) {
try {
new xyz().execute();
} catch (Exception e) {
gotoGmail(e);
}
}
}
});
return convertView;
}
private class xyz extends AsyncTask<Void, Void, Void> {
private final ProgressDialog dialog = new ProgressDialog(context);
protected void onPreExecute() {
try {
this.dialog.setMessage("Uploading...Please Wait..");
dialog.setIndeterminate(true);
dialog.setCancelable(false);
this.dialog.show();
// put your code which preload with processDialog
} catch (Exception e) {
gotoGmail(e);
}
}
@Override
protected Void doInBackground(Void... arg0) {
for (int i = 0; i < 100000; i++) {
}
it.sauronsoftware.ftp4j.FTPClient con = new it.sauronsoftware.ftp4j.FTPClient();
try {
String str_useid = RequestTo[glob_position];
con.connect("URL");
con.login("as", "asdasd");
con.changeDirectory("/rangam/RequestContent/audio");
con.setPassive(true);
con.setType(FTPClient.TYPE_BINARY);
con.upload(new java.io.File(Environment
.getExternalStorageDirectory()
+ "/audiometer/shanesh"
+ RequestId[glob_position] + "-" + str_useid + ".amr"));
String filename = "/shanesh" + RequestId[glob_position] + "-"
+ str_useid + ".amr";
con.logout();
con.disconnect(true);
String MachineName = Machinelist.str_Machinename;
sendFlagToServer(RequestId[glob_position], filename,
MachineName);
} catch (Exception e) {
gotoGmail(e);
}
return null;
}
protected void onPostExecute(final Void unused) {
if (this.dialog.isShowing()) {
try {
this.dialog.dismiss();
AlertDialog.Builder alertbox = new AlertDialog.Builder(
context);
alertbox.setTitle("Message");
alertbox.setMessage(":: Uploaded Successfully ::");
alertbox.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface arg0,
int arg1) {
Intent intent_request = new Intent(context,
SaxParser2.class);
intent_request.putExtra("value", Machinelist.str_UIDValue);
intent_request.putExtra("machineName",
Machinelist.str_Machinename);
intent_request.putExtra("captureBack_or_not", 2);
context.startActivity(intent_request);
context.finish();
}
});
alertbox.show();
} catch (Exception e) {
gotoGmail(e);
}
}
}
}
private void sendFlagToServer(String requestID, String filename,
String machineName) {
HttpURLConnection connection;
OutputStreamWriter request = null;
String MachineName = Machinelist.str_Machinename;
URL url = null;
String parameters = "RequestID=" + requestID + "&FileName=" + filename
+ "&MachineName=" + MachineName + "&RequestType=A";
try {
url = new URL(
"URL");
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();
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");
}
isr.close();
reader.close();
} catch (Exception e) {
gotoGmail(e);
}
}
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
try {
context.finish();
} catch (Exception e) {
gotoGmail(e);
}
}
return false;
}
void gotoGmail(Exception e) {
Writer writer = new StringWriter();
PrintWriter printWriter = new PrintWriter(writer);
e.printStackTrace(printWriter);
String s = writer.toString();
}
}
答案 0 :(得分：1)
确定，
首先，您必须定义“我需要加载的视图数量是多少，以便我的用户不要看到它是延迟加载的？” ：
比方说，你想要加载20行......
现在你在onscroll上，或者在你想要的任何地方，但在滚动或Adapter.getView上，你必须知道屏幕上显示的是什么......让我解释一下：
我想加载20行，因此我的用户没有注意到， 我显示了其中10个 其中10个只是隐藏（如果这个人不滚动则不显示。）
现在，当这个家伙刚刚进入我的第15排时，我还要加载10个 什么是最好的方法呢???
嗯，让我们看看，试图找到一些能够返回屏幕上显示的最后一行（ABSOLUTE）号的东西 - 这可能是一个不错的解决方案。 一个重要的解决方案可能是您的第10行或第15行是屏幕上显示的第一行吗？等等...
我觉得这样的东西应该可以解决问题。 ;）
答案 1 :(得分：0)
以下是我从Net抓起的一个示例。它是按listening to the Scroll的{{1}}加载项目。对于示例，它在ListView中加载日期。到达最终位置后，它将加载接下来的15个日期。它是ListView。您可以将适配器修改为自定义适配器。这个概念是：
从UI线程通知listview。
Never Ending List修改 您可以获得教程和完整项目here