android 中socket通信

private Button send;
 private TextView rec;
 private static Socket client;
 private boolean result=false;
 private int a=0;
 private PrintWriter write;
 private static BufferedReader read;
 public static int ac=0;
 private InputStream input;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 rec=(TextView)findViewById(R.id.textView1);;
 Thread aa=new Thread(new Runnable() {
            @Override
            public void run() {
                // TODO Auto-generated method stub
                 try {
                     //服务器的ip的地址 和端口号
                        client=new Socket(InetAddress.getByName("192.168.1.101"),4312);
                        read=new BufferedReader
                        (new InputStreamReader(client .getInputStream()));              
                        result=true;
                        a=1;                  
                        rec.setText("123");        
                     } 
                    catch(IOException e){ 
                        result=false;rec.setText("错误");
                    }   
                 finally{
                     a=1;
                 }
            }
        });
          aa.start();
          while(a==0);

                if(result){
                    String s ="";
                    try{                               
                    s = read.readLine();//执行到这一步就出错         
                     rec.setText("awq");                    

                    }
                    catch(Exception e){rec.setText("出现异常");}


    }

    每当客户端读取数据时就会出现异常，可以发送消息就是读不了怎么回事