把键盘的回车换成发送，监听键盘的弹起和隐藏

 <EditText
        android:id="@+id/mess"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:imeOptions="actionSend"
        android:inputType="text" />

mess = (EditText) findViewById(R.id.mess);
        mess.setOnEditorActionListener(new OnEditorActionListener() {
            
            @Override
            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                   if (actionId == EditorInfo.IME_ACTION_SEND)     
                   {     
                     Toast.makeText(MessageActivity.this,"fasong",0).show();   
                   }     
                return false;
            }
        });

EditText通过设置android:imeOptions来改变默认的”文本或者样式。这里举几个常用的常量值：
actionUnspecified  未指定，对应常量EditorInfo.IME_ACTION_UNSPECIFIED. 
actionNone 没有动作,对应常量EditorInfo.IME_ACTION_NONE
actionGo 去往，对应常量EditorInfo.IME_ACTION_GO
actionSearch 搜索，对应常量EditorInfo.IME_ACTION_SEARCH   
actionSend 发送，对应常量EditorInfo.IME_ACTION_SEND
actionNext 下一个，对应常量EditorInfo.IME_ACTION_NEXT 
actionDone 完成，对应常量EditorInfo.IME_ACTION_DONE

监听键盘的弹起和隐藏

package com.example.testjianpan;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnLayoutChangeListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.Toast;

public class MainActivity extends Activity implements OnLayoutChangeListener{
    private EditText edt;
    private RelativeLayout rl;
     //屏幕高度  
    private int screenHeight = 0;  
    //软件盘弹起后所占高度阀值  
    private int keyHeight = 0;  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        edt = (EditText) findViewById(R.id.edt);
        rl = (RelativeLayout) findViewById(R.id.rl);
          //获取屏幕高度  
        screenHeight = this.getWindowManager().getDefaultDisplay().getHeight();  
        //阀值设置为屏幕高度的1/3  
        keyHeight = screenHeight/3; 
        Log.v("屏幕高度",screenHeight+"");
        rl.addOnLayoutChangeListener(this) ;
                
    }
        @Override
        public void onLayoutChange(View v, int left, int top, int right,
                int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
              //现在认为只要控件将Activity向上推的高度超过了1/3屏幕高，就认为软键盘弹起  
            if(oldBottom != 0 && bottom != 0 &&(oldBottom - bottom > keyHeight)){  
                  
                Toast.makeText(MainActivity.this, "监听到软键盘弹起...", Toast.LENGTH_SHORT).show();  
              
            }else if(oldBottom != 0 && bottom != 0 &&(bottom - oldBottom > keyHeight)){  
                  
                Toast.makeText(MainActivity.this, "监听到软件盘关闭...", Toast.LENGTH_SHORT).show();  
              
            }  
            
        }
    
}