今天刚接触java的socket，自己写了一个简单的例子，客户端是android的，主要代码如下
1 protected void onCreate(Bundle savedInstanceState) { 2 3 4 5 super.onCreate(savedInstanceState); 6 setContentView(R.layout.activity_main); 7 8 btn=(Button)this.findViewById(R.id.but1); 9 editText=(EditText)this.findViewById(R.id.edit); 10 text=(TextView)this.findViewById(R.id.text1); 11 12 13 btn.setOnClickListener(new Button.OnClickListener() { 14 15 @Override 16 public void onClick(View arg0) { 17 // TODO Auto-generated method stub 18 Log.v("random", "ffxxbb"); 19 Socket socket=null; 20 String sendMsg=editText.getText().toString(); 21 Log.v("random", sendMsg); 22 String ip="172.16.45.71"; 23 24 25 26 try { 27 socket=new Socket(ip,6660); 28 Log.v("random", "socket------after"); 29 //向服务器发送消息 30 OutputStreamWriter outputStreamWriter=new OutputStreamWriter(socket.getOutputStream()); 31 BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter); 32 PrintWriter printWriter=new PrintWriter(bufferedWriter,true); 33 printWriter.println(sendMsg); 34 35 36 //接收服务器的消息 37 InputStreamReader inputStreamReader=new InputStreamReader(socket.getInputStream()); 38 BufferedReader br=new BufferedReader(inputStreamReader); 39 String msg=br.readLine(); 40 text.setText(msg); 41 42 43 printWriter.close(); 44 //br.close(); 45 //socket.close(); 46 47 } catch (UnknownHostException e) { 48 // TODO Auto-generated catch block 49 Log.v("random", "ssss"+e.getMessage()); 50 e.printStackTrace(); 51 52 } catch (IOException e) { 53 // TODO Auto-generated catch block 54 Log.v("random","vvvvvvvv"+ e.getMessage()); 55 e.printStackTrace(); 56 57 } 58 59 60 61 } 62 }); 63 }
可是，运行的时候，就报出 
的错误，刚开始以为ip或端口写错了，修改了端口也一样，于是就上网找找资料，这个异常大概意思是在主线程访问网络时出的异常。 Android在4.0之前的版本 支持在主线程中访问网络，但是在4.0以后对这部分程序进行了优化，也就是说访问网络的代码不能写在主线程中了。
修改后的代码如下
1 protected void onCreate(Bundle savedInstanceState) { 2 3 4 5 super.onCreate(savedInstanceState); 6 setContentView(R.layout.activity_main); 7 8 btn=(Button)this.findViewById(R.id.but1); 9 editText=(EditText)this.findViewById(R.id.edit); 10 text=(TextView)this.findViewById(R.id.text1); 11 12 13 btn.setOnClickListener(new Button.OnClickListener() { 14 15 @Override 16 public void onClick(View arg0) { 17 // TODO Auto-generated method stub 18 Log.v("random", "ffxxbb"); 19 Socket socket=null; 20 String sendMsg=editText.getText().toString(); 21 Log.v("random", sendMsg); 25 Thread t=new MyThread(); 26 t.start(); 27 28 } 29 }); 30 } 31 32 33 } 34 35 36 class MyThread extends Thread{ 37 38 String ip ="172.16.45.71"; 39 40 public void run(){ 41 42 try { 43 Socket socket=new Socket(ip,6669); 44 45 OutputStreamWriter outputStreamWriter=new OutputStreamWriter(socket.getOutputStream()); 48 BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter); 49 PrintWriter printWriter=new PrintWriter(bufferedWriter,true); 50 printWriter.println("ffxxbb"); 51 52 53 printWriter.close(); 54 //br.close(); 55 socket.close(); 56 57 } catch (UnknownHostException e) { 58 // TODO Auto-generated catch block 59 e.printStackTrace(); 60 } catch (IOException e) { 61 // TODO Auto-generated catch block 62 e.printStackTrace(); 63 } 64 65 } 66 }