Android之Socket的基于UDP传输

秒速五厘米 2022-08-08 00:54 251阅读 0赞

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][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][Android_UDP]

### 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

![复制代码][copycode.gif]

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();
        }

![复制代码][copycode.gif]

2、弄一个UDP帮助类，这个类主要用于发送和接收数据

![复制代码][copycode.gif]

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();
        }
    }

![复制代码][copycode.gif]

作者：[kissazi2][]  
出处：[http://www.cnblogs.com/kissazi2/][kissazi2]  
本文版权归作者所有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。

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();  
\}  
\}

[Caused by_ java.lang.UnsupportedOperationException_ Exceeded maximum number of wifi locks]: http://blog.csdn.net/sunnyfans/article/details/8083155
[Android_UDP]: http://blog.csdn.net/sunnyfans/article/details/8119993
[copycode.gif]: /images/20220805/303d5ed5beb040eebedb0e7feb7a02d2.png
[kissazi2]: http://www.cnblogs.com/kissazi2/