一个简单的Android UDP Client

（该代码在4.2.2内调试通过）

1.记得加权限

 <uses-permission android:name="android.permission.INTERNET"/>

 注意：Android 4.0之后，就不能在主线程进行socket通信，否则会抛异常。

2.代码

MainActivity.java

package mao.example.quicksend;


import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.view.View;

public class MainActivity extends Activity {
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        InitUI();
        
        //获得Button对象
        Button btnConnect = (Button) findViewById(R.id.buttonConnect);
        btnConnect.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v)
            {
                //这里处理事件
                
                //ConnectServer();
                //UDPClient udpET = new UDPClient("192.168.0.14","123");
                //udpET.start();
                //DisplayToast("点击了\"连接\"按钮");
            }
        });
        
        //发送Button
        btnConnect = (Button) findViewById(R.id.buttonSend);
        btnConnect.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v)
            {
                //这里处理事件
                SendText();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    
    /* 显示Toast  */
    public void DisplayToast(String str)
    {
        Toast.makeText(this, str, Toast.LENGTH_SHORT).show();
    }
    
    public void InitUI()
    {
        TextView text=(TextView)findViewById(R.id.editTextIP);
        text.setText("192.168.0.14");
        
        text = (TextView)findViewById(R.id.editTextFilePath);
        text.setText("Udp Client Send Test");
    }
    
    // connect server
    public void SendText() 
    {
        TextView editIP=(TextView)findViewById(R.id.editTextIP);
        TextView editText=(TextView)findViewById(R.id.editTextFilePath);
        String message = editText.getText().toString() + "\r\n"; 
        
        UDPClient udpET = new UDPClient(editIP.getText().toString(), message);
        udpET.start();
    }
}

UDPClient.java

package mao.example.quicksend;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.lang.String;

public class UDPClient extends Thread{

    public String m_serverIP;
    public String m_text;
    
    public  UDPClient(String strServerIP, String strText)
    {
        m_serverIP = strServerIP;
        m_text = strText;
    }
    
    @Override
    public void run() {
        // TODO Auto-generated method stub
        int TIMEOUT = 3000;
        int servPort = 8800;
        byte[] bytesToSend = m_text.getBytes();//"test_client".getBytes();

        try {
            InetAddress serverAddress = InetAddress.getByName(m_serverIP);
            DatagramSocket socket = new DatagramSocket();
            socket.setSoTimeout(TIMEOUT);
            
            DatagramPacket sendPacket = new DatagramPacket(bytesToSend,bytesToSend.length,serverAddress,servPort);
            socket.send(sendPacket);
                
            socket.close();
        } catch (SocketException e){
            e.printStackTrace();
        }catch(IOException e){
            e.printStackTrace();
        }
    }
}

3. activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="mao.example.quicksend.MainActivity" >

    <EditText
        android:id="@+id/editTextIP"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/text_IP" />

    <Button
        android:id="@+id/buttonConnect"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/text_connect" />

    <EditText
        android:id="@+id/editTextFilePath"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/text_filePath" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/buttonFileSel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/text_sel" />

    <Button
        android:id="@+id/buttonSend"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/text_send" />

</LinearLayout>