我正在通过 UDP 向 android 应用程序发送一些数据。因此，我创建了以下 UDPReceiver-Class：
package com.example.urowatch;
import java.net.*;
import java.nio.ByteBuffer;
import java.io.*;
public class UDPReceiver extends Thread
{
private DatagramSocket m_Socket;
private int m_BufferSize;
private Boolean m_End = false;
private int m_TotalLength;
private int m_Received;
private byte[] m_Buffer;
private byte[] m_Result;
private Boolean m_IsNewResult = false;
private float m_Progress;
private int m_ImageCount = 0;
private int m_FrameErrors = 0;
public UDPReceiver(String name, int port, int bufferSize) throws IOException
{
super(name);
m_Socket = new DatagramSocket(port);
m_BufferSize = bufferSize;
m_Socket.setBroadcast(true);
m_Socket.setReceiveBufferSize(m_BufferSize);
}
public void run()
{
while(!m_End)
{
try
{
byte[] buf = new byte[m_BufferSize];
DatagramPacket packet = new DatagramPacket(buf, buf.length);
m_Socket.receive(packet);
ProcessData(packet);
}
catch (IOException e)
{
if (!m_Socket.isClosed())
e.printStackTrace();
}
}
}
private void ProcessData(DatagramPacket packet)
{
if (packet.getLength() == 4)
{
ByteBuffer bb = ByteBuffer.wrap(packet.getData());
m_TotalLength = bb.getInt();
if (m_Received != 0)
m_FrameErrors++;
m_Received = 0;
m_Buffer = new byte[m_TotalLength];
}
else if (m_Buffer != null && m_Received != m_TotalLength)
{
int length = packet.getLength();
System.arraycopy(packet.getData(), 0, m_Buffer, m_Received, length);
m_Received += length;
m_Progress = 100 * (float)m_Received/(float)m_TotalLength;
if (m_Received == m_TotalLength)
{
m_Result = new byte[m_TotalLength];
System.arraycopy(m_Buffer, 0, m_Result, 0, m_TotalLength);
m_IsNewResult = true;
m_ImageCount++;
m_Received = 0;
}
}
}
public Boolean IsNewResult()
{
return m_IsNewResult;
}
public byte[] GetResult()
{
m_IsNewResult = false;
return m_Result;
}
public float GetProgress()
{
return m_Progress;
}
public float GetRatio()
{
return 100 * (float)m_ImageCount / (float)m_FrameErrors;
}
public void stopServer()
{
m_End = true;
if (m_Socket != null)
m_Socket.close();
}
}
我正在使用这个类：
package com.example.urowatch;
import java.io.IOException;
import java.text.DecimalFormat;
import android.os.*;
import android.app.Activity;
import android.app.AlertDialog;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import android.support.v4.app.NavUtils;
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.os.Build;
public class LiveActivity extends Activity {
private static ImageView m_ImageView1;
private static TextView m_TextView1;
private static DecimalFormat m_DF;
private static Context m_Context;
private UDPReceiver m_Receiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_live);
// Show the Up button in the action bar.
setupActionBar();
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
m_ImageView1 = (ImageView)findViewById(R.id.imageView1);
m_TextView1 = (TextView)findViewById(R.id.textView1);
m_Context = this;
m_DF = new DecimalFormat("00.00");
}
/**
* Set up the {@link android.app.ActionBar}, if the API is available.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void setupActionBar() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getActionBar().setDisplayHomeAsUpEnabled(true);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.live, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
private static Handler MyHandler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
if (msg.what == 100)
{
float[] infos = (float[])msg.obj;
m_TextView1.setText("Empfange Bild: " + m_DF.format(infos[0]) + "% (FrameErrors: " + m_DF.format(infos[1]) + "%)");
}
else if (msg.what == 101)
{
byte[] b = (byte[])msg.obj;
m_TextView1.setText("Empfange Bild: 100,00%");
m_ImageView1.setImageBitmap(BitmapFactory.decodeByteArray(b, 0, b.length));
}
else if (msg.what == 102)
{
AlertDialog.Builder b = new AlertDialog.Builder(m_Context);
b.setTitle("Fehler");
b.setMessage("Es ist folgende Exception aufgetreten:\n" + (Exception)msg.obj);
b.setNeutralButton("OK", null);
b.show();
}
}
};
@Override
public void onBackPressed() {
super.onBackPressed();
if (m_Receiver != null)
m_Receiver.stopServer();
finish();
}
@Override
public void onPause()
{
m_Receiver.stopServer();
super.onPause();
}
@Override
protected void onResume()
{
try {
m_Receiver = new UDPReceiver("UDPReceiver", 5678, 1024);
m_Receiver.start();
} catch (IOException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
AlertDialog.Builder b = new AlertDialog.Builder(this);
b.setTitle("Fehler");
b.setMessage("Es ist folgende Exception aufgetreten:\n" + e1);
b.setNeutralButton("OK", null);
b.show();
}
// Thread thread = new Thread()
// {
// @Override
// public void run()
// {
// while(true)
// {
// try {
//sleep(250);
Toast.makeText(getBaseContext(), "Runing Thread", Toast.LENGTH_SHORT).show();
Update();
// } catch (InterruptedException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// MyHandler.sendMessage(MyHandler.obtainMessage(102, e));
// }
// }
// }
// };
// thread.start();
super.onResume();
}
public void buttonClick(View v)
{
Update();
}
private void Update()
{
if (m_Receiver != null)
{
if (m_Receiver.IsNewResult())
{
byte[] b = m_Receiver.GetResult();
MyHandler.sendMessage(MyHandler.obtainMessage(101, b));
}
else
{
float[] infos = new float[2];
infos[0] = m_Receiver.GetProgress();
infos[1] = m_Receiver.GetRatio();
MyHandler.sendMessage(MyHandler.obtainMessage(100, infos));
}
}
}
}
如您所见，我想通过线程检查 UDPReceiver-Object 的状态（是否有新的完整字节 [] 准备好？）。要更新 GUI，线程必须向 MyHandler 发送一条消息，该消息将更新 GUI。
此刻我必须单击一个按钮来引发 buttonClick-Event。稍后我想在注释的线程结构中执行此操作。
现在，这是我的问题：我启动了 Activity，一切正常。然后我开始用我的 UDP-Sender 手动发送一个数据包（它有效，我用 C#-UDP-Receiver 验证了它）。第一个数据包收到很好。然后我也发送接收到的第二个数据包。但从现在开始，我的断点在 m_Socket.receive(packet); 不会再被击中了！
我不知道这种行为是什么原因造成的，让这个应用程序工作对我来说非常重要。请，如果您有任何想法或只是猜测，请告诉我。