需求：通过udp传输方式，快速找到同局域网内某设备
思路：需要某设备发送，手机接收。或者手机发送，设备接收，两个设备需在同一局域网内
1、建立udpsocket服务
2、提供数据，并将数据封装到数据包中
3、通过socket服务的发送功能，将数据包发送出去。
4、关闭资源。
DatagramSocket：此类表示用来发送和接收数据报包的套接字。在 DatagramSocket 上总是启用 UDP 广播发送。
DatagramPacket：此类表示数据报包。数据报包用来实现无连接包投递服务。每条报文仅根据该包中包含的信息从一台机器路由到另一台机器。从一台机器发送到另一台机器的多个包可能选择不同的路由，也可能按不同的顺序到达。不对包投递做出保证。
先看个图：
UDP发送数据
UDP接收数据
具体代码如下：
package com.fzm.coldwallet.ui.activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import com.fzm.coldwallet.R;
import com.fzm.coldwallet.ui.base.BaseActivity;
import com.fzm.coldwallet.utils.ToastUtils;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;
public class TestActivity extends BaseActivity {
@BindView(R.id.btn_send)
Button btnSend;
@BindView(R.id.btn_wait)
Button btnWait;
@BindView(R.id.tv_data)
TextView tvData;
private MainHandle mMainHandle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
ButterKnife.bind(this);
mMainHandle = new MainHandle();
}
@OnClick({R.id.btn_send, R.id.btn_wait})
public void onViewClicked(View view) {
switch (view.getId()) {
case R.id.btn_send:
sendMsg();
break;
case R.id.btn_wait:
new Thread(new Runnable() {
@Override
public void run() {
waitMsg();
}
}).start();
break;
}
}
private String sLog = "";
private void sendMsg() {
try {
final DatagramSocket hostSocket = new DatagramSocket();
// 设置接收超时时间
hostSocket.setSoTimeout(1500);
final String sendData = "my name is zzz";
InetAddress broadIP = InetAddress.getByName("255.255.255.255");
final DatagramPacket sendPack = new DatagramPacket(sendData.getBytes(), sendData.length(), broadIP, 9901);
new Timer().schedule(new TimerTask() {
@Override
public void run() {
String log = sendData + new SimpleDateFormat("yyyy-MM-dd HH：mm：ss").format(new Date()) + "\n";
Log.v("tag", Thread.currentThread() + log);
if (sLog.split("\n").length > 10) {
sLog = "";
}
try {
hostSocket.send(sendPack);
sLog += log;
runOnUiThread(new Runnable() {
@Override
public void run() {
tvData.setText(sLog);
}
});
} catch (Exception e) {
e.printStackTrace();
}
}
}, 0, 1000);
} catch (Exception e) {
e.printStackTrace();
}
}
private String rLog = "";
private void waitMsg() {
byte[] buffer = new byte[1024];
/*在这里同样使用约定好的端口*/
int port = 9901;
DatagramSocket server = null;
try {
server = new DatagramSocket(port);
final DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
while (true) {
// 等待主机的搜索
try {
server.receive(packet);
final String s = new String(packet.getData(), 0, packet.getLength(), "UTF-8");
String log = packet.getAddress() + ",port:" + packet.getPort() + "," + s + "\n";
Log.v("tag", log);
rLog += log;
if (rLog.split("\n").length > 10) {
rLog = "";
}
mMainHandle.sendEmptyMessage(1);
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (SocketException e) {
e.printStackTrace();
} finally {
if (server != null)
server.close();
}
}
class MainHandle extends Handler {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
tvData.setText(rLog);
}
}
}
最后别忘了网络权限：