我参加了一个网络课程，并被分配了一个我们可以在任何语言或环境中完成的项目。作为Android爱好者，我自然想在手机上做这件事。我遇到问题的部分应该很简单，我开始认为我无法在手机之间使用UDP建立连接。我想要做的是使用一部手机作为服务器，一部作为客户端。客户端向服务器发送消息，服务器将字符串更改为大写。 （这不是项目，但是看看它是否正常工作是一个很好的步骤。）有谁知道为什么服务器和客户端不会连接或甚至可能？
这是服务器，下面是客户端，主启动屏幕和main.xml
package com.csc.networking;
import java.net.*;
import android.util.Log;
public class UDPServer
{
public void main() throws Exception
{
Log.d("s","1");
DatagramSocket serverSocket = new DatagramSocket(6699);//create a datagram socket at the specified port number
byte[] receiveData = new byte[1024];
byte[] sendData = new byte[1024];
Log.d("s","2");
while(true)
{
Log.d("s","3");
DatagramPacket receivePacket = new DatagramPacket(receiveData,receiveData.length);
//To Do: construct a DatagramPacket object called receivePacket. Use the constructor of the class DatagramPacket
//that takes two parameters: 1. the array of bytes (receiveData) and 2. the length of that array.
Log.d("s","3.5");
//To Do: use the method receive on the DatagramSocket object to receive the packet sent from the client.
//the method receive takes one parameter (the DatagramPacket object constructed in the above step).
serverSocket.receive(receivePacket);
Log.d("s","again");
Log.d("s","3.75");
String sentence = new String(receivePacket.getData());//extract the String from the array of bytes.
Log.d("s",sentence);
Log.d("s","4");
InetAddress IPAddress = receivePacket.getAddress();//extract the IP address of the client
int port = receivePacket.getPort();//extract the port number from the packet
String capitalizedSentence = sentence.toUpperCase();//change the sentence received by the server
sendData = capitalizedSentence.getBytes();//convert it to an array of bytes
Log.d("s","5");
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
//To Do: construct a DatagramPacket object called sendPacket. Use the constructor of the class DatagramPacket
//that takes 4 parameters: 1. the array of bytes to be sent. 2. the length of that array of bytes.
//3. the IP address of the client (use the object IPAddress) and 4. the port number of the process running in
//the client.
//To Do: send the packet to the client using the method send on the DatagramSocket object. The metho send
//takes one parameter which is the packet constructed in the above step.
Log.d("s","5.5");
serverSocket.send(sendPacket );
Log.d("s","6");
}
}
}
package com.csc.networking;
import java.io.*;
import java.net.*;
import android.util.Log;
import android.widget.*;
public class UDPClient {
public void main(String string) throws Exception
{
Log.d("help", "1");
//EditText connectAddress = (EditText)findViewById(R.id.connectAddress);
Log.d("help", "2");
String hostIP = "10.60.5.79"; //connectAddress.getText().toString();
Log.d("help", "3");
String coded = string;
Log.d("help", "4");
DatagramSocket clientSocket = new DatagramSocket();//this line creates a datagram socket, this does not
//create a TCP connection with the server, note how we do not have server and process info as parameters to
//the constructor
Log.d("help", "5");
InetAddress IPAddress = InetAddress.getByName(hostIP); //this line invokes DNS to lookup the IP address
//of the hostname. If IP address is provided, it stores it in the object IPAddress.
Log.d("help", "6");
byte[] sendData = new byte[1024]; //array of bytes to be sent to server
Log.d("help", "7");
byte[] receiveData = new byte[1024]; //array of bytes that client will receive from server
Log.d("help", "8");
sendData = coded.getBytes(); //this converts sentence to an array of bytes and stores it in sendData.
Log.d("help", "9");
DatagramPacket sendPacket = new DatagramPacket(sendData,sendData.length,IPAddress,6699);
//To DO: construct a DatagramPacket object called sendPacket. The constructor of the DatagramPacket class
//takes the following parameters: 1. the array of bytes to be sent. 2. the length of the array of bytes.
//3. the IPAddress of the destination (use the object IPAddress) and 4. the port number of the process running
//at the destination.
Log.d("help", "10");
clientSocket.send(sendPacket);
//To DO: call the method send on the DatagramSocket object to send the datagram packet. The method send takes
//the DatagramPacket object as a prameter and sends it through the socket.
Log.d("help", "11");
DatagramPacket receivePacket = new DatagramPacket(receiveData,receiveData.length);
//To Do: construct a new DatagramPacket object called recievePacket. This is the packet that the client will
//receive from the destination. Use the constructor that takes two parameters: 1. an array of bytes (receiveData) and
//2. the length of that array.
Log.d("help", "12");
clientSocket.receive(receivePacket);
//To Do: use the method receive on the DatagramSocket object to receive the datagram packet from the server.
//The method receive takes a parameter which is the DatagramPacket constructed in the above step.
Log.d("help", "13");
String modifiedSentence = new String(receivePacket.getData());//this converts an array of bytes to a string.
Log.d("help", "14");
TextView decoded = (TextView)findViewById(R.id.decoded);
Log.d("help", "15");
decoded.setText(modifiedSentence);
Log.d("help", "16");
clientSocket.close();//this closes the connection.
Log.d("help", "17");
}
private EditText findViewById(int connectaddress) {
// TODO Auto-generated method stub
return null;
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:baselineAligned="true" android:orientation="vertical"
android:layout_width="wrap_content" android:layout_height="fill_parent">
<TextView android:text="@string/Title" android:id="@+id/Title"
android:layout_width="fill_parent" android:gravity="center"
android:textSize="24px" android:layout_height="wrap_content" />
<EditText android:id="@+id/editText1" android:layout_below="@+id/Title"
android:layout_alignLeft="@+id/Title" android:layout_alignRight="@+id/Title"
android:layout_width="fill_parent"
android:layout_height="wrap_content" android:scrollbarAlwaysDrawVerticalTrack="true" android:scrollbars="vertical" android:singleLine="true" android:hint="@string/Hint"/>
<RelativeLayout android:layout_width="wrap_content"
android:layout_below="@+id/editText1" android:id="@+id/relativeLayout1"
android:layout_height="wrap_content" android:layout_alignLeft="@+id/editText1"
android:layout_alignRight="@+id/editText1">
<Button android:layout_width="wrap_content"
android:layout_below="@+id/startServer" android:layout_height="wrap_content"
android:layout_alignLeft="@+id/startServer"
android:layout_alignRight="@+id/startServer" android:id="@+id/Send"
android:text="@string/Send" />
<EditText android:layout_width="wrap_content" android:layout_below="@+id/Send" android:layout_height="wrap_content" android:layout_alignLeft="@+id/Send" android:layout_alignRight="@+id/Send" android:id="@+id/connectAddress" android:hint="Enter Ip Address Here"></EditText>
<TextView android:text="Decoded" android:layout_width="wrap_content" android:layout_below="@+id/connectAddress" android:id="@+id/decoded" android:layout_height="wrap_content" android:layout_alignLeft="@+id/connectAddress" android:layout_alignRight="@+id/connectAddress"></TextView>
<Button android:layout_width="fill_parent" android:id="@+id/startServer" android:text="@string/Start " android:layout_height="wrap_content" android:layout_alignParentRight="true"></Button>
</RelativeLayout>
</RelativeLayout>
package com.csc.networking;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class launchScreen extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button SendButton = (Button)findViewById(R.id.Send);
SendButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
Log.d("click", "1");
EditText codedMessage = (EditText)findViewById(R.id.editText1);
UDPClient client = new UDPClient();
String msg = codedMessage.getText().toString();
Log.d("click", msg);
Log.d("click", "2");
client.main(msg);
Log.d("click", "3");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
Button ServerButton = (Button)findViewById(R.id.startServer);
ServerButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
UDPServer server = new UDPServer();
server.main();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
}
答案 0 :(得分：1)
答案 1 :(得分：1)
首先，你要尝试在UI线程上做网络内容。在较新的Android中，它会导致异常，用户体验非常糟糕。当服务器或客户端在方法中等待时：
socket.receive()
更好的想法是将这些东西放在线程或AsyncTasks中。这可能对网络networking in android
有帮助根据您的问题，我建议多次发送此数据包。 UDP不保证数据包传输，只发送一个数据包是非常危险的。
将socket.send()方法置于循环中，然后发送10次相同的数据包。
您也可以尝试将其发送到您的计算机IP地址，并使用类似的软件进行检查 Wireshark如果收到它。
最后但并非最不重要的是，在您的情况下，更好的选择是TCP客户端和服务器，其中数据包传递得到保证。 UDP在流媒体等方面是最好的，其中重传根本没用。
答案 2 :(得分：0)
如果您正在使用3G连接，则入站防火墙可能会阻止您的（传入）连接。见this
我的建议是从无线本地网络开始，以便IP将是静态的/众所周知的，然后转移到互联网连接。