package com.ravi.seggerclient;
public class MainActivity extends Activity
{
EditText text,text2;
String selectedImagePath,ll=null;
Timer ravi;
static DatagramSocket clsoc;
static InetAddress ip;
static File ff;
byte[] arr = null;
static int len,totpac;
static RandomAccessFile raf;
static FileChannel chan;
static int buffsize;
static int i=0,id=0,numRead=0;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
text = (EditText)findViewById(R.id.editText1);
text2 = (EditText)findViewById(R.id.editText2);
final String state = Environment.getExternalStorageState();
((Button) findViewById(R.id.button1))
.setOnClickListener(new OnClickListener()
{
public void onClick(View arg0)
{
try
{
if (Environment.MEDIA_MOUNTED.equals(state))
{
String root = Environment.getExternalStorageDirectory().toString();
selectedImagePath = root +"/Nenjodu.mp4"; ff = new File(selectedImagePath);
text.setText(selectedImagePath+"File Is Found"+"File length"+ff.length());
}
}
catch(Exception e)
{
text.setText(""+e);
}
}
});
((Button) findViewById(R.id.button2))
.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0)
{
try
{
Ravii rav = new Ravii();
ll="NOT SENT";
ll = rav.execute().get();
text2.setText(""+ll);
}
catch(Exception e)
{
Log.d("Error in Sending",""+e);
}
}
});
}
private class Ravii extends AsyncTask<String,Void,String>
{
@Override
protected String doInBackground(String... params)
{
// TODO Auto-generated method stub
try{
clsoc = new DatagramSocket();
ip = InetAddress.getByName("192.168.137.1");
len = (int)ff.length();
totpac = len/(30*1024)+1;
buffsize = 30;
String ss ="#"+totpac+"&";
Log.d("No of Packets",""+totpac);
byte[] fsize = new byte[1024];
fsize = ss.getBytes();
DatagramPacket dp = new DatagramPacket(fsize,fsize.length,ip,8000);
clsoc.send(dp);
raf = new RandomAccessFile(ff,"rw");
chan = raf.getChannel();
while(numRead>=0)
{
ByteBuffer buf = ByteBuffer.allocate(1024*buffsize);
if(i==id)
numRead = chan.read(buf);
if((numRead>0)&&(i==id))
{
arr = new byte[numRead];
System.arraycopy(buf.array(),0,arr,0,numRead);
DatagramPacket sp = new DatagramPacket(arr,arr.length,ip,8000);
clsoc.send(sp);
i++;
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
clsoc.receive(receivePacket);
String mod = new String(receivePacket.getData());
System.out.println("\n" + mod);
id=Integer.parseInt(mod.substring(mod.indexOf("#") + 1, mod.indexOf("&")));
}
else if((numRead>0)&&(i!=id))
{
i--;
DatagramPacket sp = new DatagramPacket(arr,arr.length,ip,8000);
clsoc.send(sp);
text2.setText("ReSent "+i+" packet");
i++;
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
clsoc.receive(receivePacket);
String mod = new String(receivePacket.getData());
id=Integer.parseInt(mod.substring(mod.indexOf("#") + 1, mod.indexOf("&")));
}
else
{
Toast.makeText(getApplicationContext(),"Nothing to Send" , Toast.LENGTH_SHORT).show();
}
}
return "SuccessFul";
}
catch(Exception e)
{
Log.d("Exception in the Client Sending",""+e);
}
}
}
}
您好我是Android编程的新手。这是我的代码，客户端使用UDP协议从一个移动设备向其他移动设备发送大文件。虽然UDP不是这项工作的首选。它是我项目的一部分。这里当我在Android中启动Networking时，我开始知道网络是使用AsyncTask在Android中使用Background线程完成的，但是当我想在后台线程中长时间运行循环时，循环包括网络（这是Asynctask首选的原因），我我正面临一个错误 Android无法在未调用Looper.prepare（）的线程内创建处理程序。 如何克服这一点以及如何在Android编程中一起运行网络和循环操作。欢迎任何建议。
答案 0 :(得分：0)
AsyncTask可以正确，轻松地使用UI线程。该类允许执行后台操作并在UI线程上发布结果，而无需操纵线程和/或处理程序。
AsyncTask旨在成为Thread和Handler的辅助类，并不构成通用的线程框架。理想情况下，AsyncTasks应该用于短操作（最多几秒钟。）
避免使用AsyncTask进行长时间阻止网络操作。而是使用基本的线程
私有类Ravii扩展了Thread {
public void run() {
try {
clsoc = new DatagramSocket();
ip = InetAddress.getByName("192.168.137.1");
len = (int) ff.length();
totpac = len / (30 * 1024) + 1;
buffsize = 30;
String ss = "#" + totpac + "&";
Log.d("No of Packets", "" + totpac);
byte[] fsize = new byte[1024];
fsize = ss.getBytes();
DatagramPacket dp = new DatagramPacket(fsize, fsize.length, ip,
8000);
clsoc.send(dp);
raf = new RandomAccessFile(ff, "rw");
chan = raf.getChannel();
while (numRead >= 0) {
ByteBuffer buf = ByteBuffer.allocate(1024 * buffsize);
if (i == id)
numRead = chan.read(buf);
if ((numRead > 0) && (i == id)) {
arr = new byte[numRead];
System.arraycopy(buf.array(), 0, arr, 0, numRead);
DatagramPacket sp = new DatagramPacket(arr, arr.length, ip,
8000);
clsoc.send(sp);
i++;
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(
receiveData, receiveData.length);
clsoc.receive(receivePacket);
String mod = new String(receivePacket.getData());
System.out.println("\n" + mod);
id = Integer.parseInt(mod.substring(mod.indexOf("#") + 1,
mod.indexOf("&")));
} else if ((numRead > 0) && (i != id)) {
i--;
DatagramPacket sp = new DatagramPacket(arr, arr.length, ip,
8000);
clsoc.send(sp);
text2.setText("ReSent " + i + " packet");
i++;
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(
receiveData, receiveData.length);
clsoc.receive(receivePacket);
String mod = new String(receivePacket.getData());
id = Integer.parseInt(mod.substring(mod.indexOf("#") + 1,
mod.indexOf("&")));
} else {
Toast.makeText(getApplicationContext(), "Nothing to Send",
Toast.LENGTH_SHORT).show();
}
}
return "SuccessFul";
} catch (Exception e) {
Log.d("Exception in the Client Sending", "" + e);
}
}
}