Activtyy 实现TextView.OnEditorActionListener这个接口  
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {  
       if (event != null) {  
           // if shift key is down, then we want to insert the ‘\n‘ char in the TextView;  注意看下注释  
           // otherwise, the default action is to send the message.  
           if (!event.isShiftPressed()) {  
                 
               return true;  
           }  
           return false;  
       }