解决android.os.NetworkOnMainThreadException

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 }