接收方创建步骤：
1. 创建一个DatagramSocket对象，并指定监听的端口号
DatagramSocket socket = new DatagramSocket (4567);
2. 创建一个byte数组用于接收
byte data[] = new byte[1024];
3. 创建一个空的DatagramPackage对象
DatagramPackage package = new DatagramPackage(data , data.length);
4. 使用receive方法接收发送方所发送的数据,同时这也是一个阻塞的方法
socket.receive(package);
5. 得到发送过来的数据
new String(package.getData() , package.getOffset() , package.getLength());
发送方创建步骤：
1. 创建一个DatagramSocket对象
DatagramSocket socket = new DatagramSocket (4567);
2. 创建一个 InetAddress ， 相当于是地址
InetAddress serverAddress = InetAddress.getByName("想要发送到的那个IP地址");
3. 这是随意发送一个数据
String str = "hello";
4. 转为byte类型
byte data[] = str.getBytes();
5. 创建一个DatagramPacket 对象，并指定要讲这个数据包发送到网络当中的哪个地址，以及端口号
DatagramPacket package = new DatagramPacket (data , data.length , serverAddress , 4567);
6. 调用DatagramSocket对象的send方法 发送数据
socket . send(package);
http://www.cnblogs.com/lee0oo0/archive/2012/04/04/2431907.html
一、有的手机不能直接接收UDP包，可能是手机厂商在定制Rom的时候把这个功能给关掉了。
1、可先在oncreate()方法里面实例化一个WifiManager.MulticastLock 对象lock；具体如下：
WifiManager manager = (WifiManager) this
.getSystemService(Context.WIFI_SERVICE);
WifiManager.MulticastLock lock= manager.createMulticastLock("test wifi");
2、在调用广播发送、接收报文之前先调用lock.acquire()方法；
3、用完之后及时调用lock.release()释放资源，否决多次调用lock.acquire()方法，程序可能会崩，详情请见
Caused by: java.lang.UnsupportedOperationException: Exceeded maximum number of wifi locks
注；记得在配置文件里面添加如下权限：
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
经过这样处理后，多数手机都能正常发送接收到广播报文。
本小点转载自Android手机接收不到UDP报文
二、在UDP通信中，android端发送UDP广播包没有问题。至于接收的话，有时候不能接收到包。
在UDP通信中，Android端发送UDP广播包没有问题。至于接收的话，有时候不能接收到包。但是如果UDP包中指定了目标主机的地址的话，那么android端就能正常接收。
下面上一段代码，大家可用这段代码进行测试。
1、在一个Service里面，我们创建一个线程
public void onCreate() {//用于创建线程
WifiManager manager = (WifiManager) this
.getSystemService(Context.WIFI_SERVICE);
udphelper = new UdpHelper(manager);
//传递WifiManager对象，以便在UDPHelper类里面使用MulticastLock
udphelper.addObserver(MsgReceiveService.this);
tReceived = new Thread(udphelper);
tReceived.start();
super.onCreate();
}
2、弄一个UDP帮助类，这个类主要用于发送和接收数据
package com.example.com.ihome.bang.util;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Observable;
import com.example.com.ihome.bang.tool.SendThread;
import android.net.wifi.WifiManager;
import android.util.Log;
/**
*
* UdpHelper帮助类
*
* @author 陈喆榕
*
*/
public class UdpHelper implements Runnable {
public Boolean IsThreadDisable = false;//指示监听线程是否终止
private static WifiManager.MulticastLock lock;
InetAddress mInetAddress;
public UdpHelper(WifiManager manager) {
this.lock= manager.createMulticastLock("UDPwifi");
}
public void StartListen() {
// UDP服务器监听的端口
Integer port = 8903;
// 接收的字节大小，客户端发送的数据不能超过这个大小
byte[] message = new byte[100];
try {
// 建立Socket连接
DatagramSocket datagramSocket = new DatagramSocket(port);
datagramSocket.setBroadcast(true);
DatagramPacket datagramPacket = new DatagramPacket(message,
message.length);
try {
while (!IsThreadDisable) {
// 准备接收数据
Log.d("UDP Demo", "准备接受");
this.lock.acquire();
datagramSocket.receive(datagramPacket);
String strMsg=new String(datagramPacket.getData()).trim();
Log.d("UDP Demo", datagramPacket.getAddress()
.getHostAddress().toString()
+ ":" +strMsg );this.lock.release();
}
} catch (IOException e) {//IOException
e.printStackTrace();
}
} catch (SocketException e) {
e.printStackTrace();
}
}
public static void send(String message) {
message = (message == null ? "Hello IdeasAndroid!" : message);
int server_port = 8904;
Log.d("UDP Demo", "UDP发送数据:"+message);
DatagramSocket s = null;
try {
s = new DatagramSocket();
} catch (SocketException e) {
e.printStackTrace();
}
InetAddress local = null;
try {
local = InetAddress.getByName("255.255.255.255");
} catch (UnknownHostException e) {
e.printStackTrace();
}
int msg_length = message.length();
byte[] messageByte = message.getBytes();
DatagramPacket p = new DatagramPacket(messageByte, msg_length, local,
server_port);
try {
s.send(p);
s.close();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void run() {
StartListen();
}
}
最后， 添加个人的实例 ：
package com.example.android.helloactivity;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import com.example.andriod.udp.UDPClient;
import com.example.andriod.udp.UDPServer;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainAct extends Activity {
EditText msg_et = null;
Button send_bt = null;
TextView info_tv = null;
private static final String TAG ="MainAct";
private UDPClient client;
private String sendInfo;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.udp_test);
msg_et = (EditText) findViewById(R.id.edit_msg);
send_bt = (Button) findViewById(R.id.send_bt);
info_tv = (TextView) findViewById(R.id.receive_msg);
info_tv.setText("source");
// 开启服务器
ExecutorService exec = Executors.newCachedThreadPool();
UDPServer server = new UDPServer();
exec.execute(server);
// 发送消息
send_bt.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
myThread1 thread = new myThread1("22");
new Thread(thread).start();
}
});
}
final Handler mHander = new Handler() {
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
//super.handleMessage(msg);
info_tv.setText(sendInfo);
Log.d(TAG, "client.send()=");
}
};
class myThread1 implements Runnable {
private String threadName;
public myThread1(String name) {
this.threadName = name;
}
public void run() {
Log.d(TAG, "MyThread execu"+msg_et.getText().toString());
client = new UDPClient(msg_et.getText().toString());
sendInfo=client.send();
Message msg = mHander.obtainMessage();
msg.arg1=1;
mHander.sendMessage(msg);
Log.d(TAG, "client.send()=");
}
}
}
package com.example.andriod.udp;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import android.util.Log;
public class UDPServer implements Runnable {
private static final int PORT = 6000;
private byte[] msg = new byte[2048];
private boolean life = true;
public UDPServer() {
}
public boolean isLife() {
return life;
}
public void setLife(boolean life) {
this.life = life;
}
@Override
public void run() {
DatagramSocket dSocket = null;
DatagramPacket dPacket = new DatagramPacket(msg, msg.length);
try {
dSocket = new DatagramSocket(PORT);
while (life) {
try {
dSocket.receive(dPacket);
Log.d("tian msg sever received",
new String(dPacket.getData(), dPacket.getOffset(),
dPacket.getLength())
+ "dPacket.getLength()="
+ dPacket.getLength());
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (SocketException e) {
e.printStackTrace();
}
}
}
package com.example.andriod.udp;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import android.util.Log;
public class UDPClient {
private static final int SERVER_PORT = 6000;
private DatagramSocket dSocket = null;
private String msg;
public UDPClient(String msg) {
super();
this.msg = msg;
}
public String send() {
StringBuilder sb = new StringBuilder();
InetAddress local = null;
try {
local = InetAddress.getByName("localhost"); // 本机测试
sb.append("已找到服务器,连接中...").append("/n");
} catch (UnknownHostException e) {
sb.append("未找到服务器.").append("/n");
e.printStackTrace();
}
try {
dSocket = new DatagramSocket(); // 注意此处要先在配置文件里设置权限,否则会抛权限不足的异常
sb.append("正在连接服务器...").append("/n");
} catch (SocketException e) {
e.printStackTrace();
sb.append("服务器连接失败.").append("/n");
}
int msg_len = msg == null ? 0 : msg.length();
DatagramPacket dPacket = new DatagramPacket(msg.getBytes(), msg_len,
local, SERVER_PORT);
try {
dSocket.send(dPacket);
Log.d("tian", "msg=="+msg+"dpackage="+dPacket.getData()+"dPacket.leng="+dPacket.getLength());
sb.append("消息发送成功!").append("/n");
} catch (IOException e) {
e.printStackTrace();
sb.append("消息发送失败.").append("/n");
}
dSocket.close();
return sb.toString();
}
}
时间： 2024-10-16 12:37:16