[英]Listing of the Network Devices in Android
在这里已回答类似或相同的问题
我正在创建一个Android应用程序,该应用程序将广播消息发送到网络,并准备响应的设备列表。
现在我做了什么:
我创建了一个Activity
类DeviceManagerWindow.java
,它调用了一个线程Sender.java
。 Sender.java
负责发送广播消息。
然后, DeviceManagerWindow.java
调用另一个线程,该线程负责侦听响应的设备。 devices
回复后,将在活动中列出回复的设备。 为此,我有一个名为deviceList
的TableLayout
。
我写了什么代码:
DeviceManagerWindow.java This method is called when a button for search is pressed
public void searchDevice(View v) throws IOException, InterruptedException
{
//Log.v("TableLayout:",view.toString());
sendMulticastFlyport = new Thread(new FlyportSender(MAC));
sendMulticastFlyport.start();
new Thread()
{
public void run()
{
MulticastSocket socketComputer=null;
try
{
socketComputer = new MulticastSocket(WifiConstants.COMPUTER_RECV_PORT);
socketComputer.joinGroup(InetAddress.getByName(WifiConstants.COMPUTER_NETWORK_ADDR));
socketComputer.setSoTimeout(1*60*1000);
byte[] inBufComputer = new byte[1024];
DatagramPacket inPacketComputer = new DatagramPacket(inBufComputer, inBufComputer.length);
while(true)
{
System.out.println("Listening...");
socketComputer.receive(inPacketComputer);
System.out.println("Received");
String msg = new String(inBufComputer, 0, inPacketComputer.getLength());
DeviceInformation device = new DeviceInformation(1, msg, inPacketComputer.getAddress().toString());
addDevice(device, false, 1);
Log.v("Received:","Received Computer From :" + inPacketComputer.getAddress() + " Msg : " + msg);
//System.out.write(inPacket.getData(),0,inPacket.getLength());
System.out.println();
Thread.sleep(2000);
}
}
catch(Exception e)
{
Log.v("Exception:","During Receiving Computer: "+e.toString());
try
{
addDevice(null, true, 1);
}
catch (IOException e1)
{
Log.v("Exception:", "Computer End Error: " +e1);
}
}
finally
{
socketComputer.close();
}
}
}.start();
以下代码创建一个列表:
public void addDevice(DeviceInformation device, boolean bool, int type) throws IOException
{
TableLayout tb = (TableLayout) findViewById(R.id.DeviceList);
Log.v("addDevice","Called");
if(bool)
{
LayoutParams layout = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
TableRow tr = new TableRow(getApplicationContext());
TextView tv = new TextView(getApplicationContext());
System.out.println(tb);
tv.setLayoutParams(layout);
tr.setLayoutParams(layout);
String message;
Log.v("addDevice","Device Timeout");
switch(type)
{
case 1:
computerEnd=true;
break;
case 2:
raspberryEnd=true;
break;
case 3:
flyportEnd=true;
break;
}
if(computerEnd && raspberryEnd && flyportEnd)
{
if(rowCounter>0)
{
message = "No More Devices";
}
else
{
message = "No Devices Found";
}
tv.setText(message);
tv.setTextColor(Color.WHITE);
if(rowCounter%2==0)
{
tr.setBackgroundColor(Color.DKGRAY);
}
else
{
tr.setBackgroundColor(Color.GRAY);
}
tv.setVisibility(1);
tr.addView(tv);
tb.addView(tr);
}
}
else
{
LayoutParams layout = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
TableRow tr = new TableRow(getApplicationContext());
TextView tv = new TextView(getApplicationContext());
tv.setLayoutParams(layout);
tr.setLayoutParams(layout);
Log.v("addDevice","Received");
String textToDisplay = device.getDeviceTypeString()+"\n"+device.getIPAddress(); //Write the text to display
tv.setText(textToDisplay);
tv.setTextColor(Color.WHITE);
Drawable img;
if(device.getDeviceType()==1)
{
img = getApplicationContext().getResources().getDrawable(R.drawable.pc);
}
else if(device.getDeviceType()==2)
{
img = getApplicationContext().getResources().getDrawable(R.drawable.raspberry);
}
else
{
img = getApplicationContext().getResources().getDrawable(R.drawable.flyport);
}
img.setBounds(0,0,70,45);
tv.setCompoundDrawables(null, null, img, null);
tv.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
}
});
if(rowCounter%2==0)
{
tr.setBackgroundColor(Color.DKGRAY);
}
else
{
tr.setBackgroundColor(Color.GRAY);
}
rowCounter++;
Log.v("Result","Device Added");
}
}
现在,它向我显示了logCat中的错误,如下所示:
05-11 22:01:10.165: E/AndroidRuntime(13873): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
我从中得出的结论是,仅允许UIThread访问创建的视图。
以前我曾尝试过:
new Thread()
{
public void run()
{
runOnUiThread(){
MulticastSocket socketComputer=null;
try
{
....
....
....
}
}
那时我收到一个错误:
主线程无法访问网络
在此之前,我曾尝试使用从Receiving.java
线程文件中调用的synchronized
方法。 但是它也给出了不创建列表的错误。
我尝试了所有可能的方法。
现在我该怎么办?
您发现正确。 现在,您可以学习使用处理程序将信息传递到UI线程(请参阅http://www.techotopia.com/index.php/A_Basic_Overview_of_Android_Threads_and_Thread_handlers )或AsyncTask(请参见http://developer.android.com/reference/ android / os / AsyncTask.html )。
我个人更喜欢AsyncTask。 您可以将执行搜索的代码粘贴到doInBackground()方法中(不需要使用单独的线程,doInBackground()已经为您完成此操作),并将与UI相关的代码(列表创建代码)粘贴到onPostExecute( ) 方法。 如果尚未从链接中充分了解AsyncTask的工作方式,请搜索更多示例。
编辑:如果您希望设备搜索代码无限期运行,则必须诉诸处理程序,因为AsyncTask希望doInBackground()方法在运行onPostExecute()之前完成。 查看哪个选项更适合您的需求。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.