Android应用中出现软键盘遮挡住按钮如何解决

<ScrollView
android:id="@+id/scrollview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fadingEdge="none"
android:scrollbars="none">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="center_horizontal"
android:layout_marginTop="20dp"
android:src="@mipmap/ic_loginhead"/>
<EditText
android:id="@+id/et_usernamelogin_username"

android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginTop="10dp"
android:background="@null"
android:hint="请输入已验证手机"
android:inputType="number"
android:lines="1"
android:maxLength="11"/>
<ImageView
android:layout_width="match_parent"
android:layout_height="2px"
android:layout_marginLeft="50dp"
android:layout_marginRight="50dp"
android:background="@color/pating_line"/>
<EditText
android:id="@+id/et_usernamelogin_password"

android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginTop="20dp"
android:background="@null"
android:digits="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_&#63;"
android:hint="请输入密码"
android:inputType="textPassword"/>
<ImageView
android:layout_width="match_parent"
android:layout_height="2px"
android:layout_marginLeft="50dp"
android:layout_marginRight="50dp"
android:background="@color/pating_line"/>
<Button
android:id="@+id/btn_usernamelogin_dologin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginLeft="50dp"
android:layout_marginRight="50dp"
android:layout_marginTop="30dp"
android:background="@drawable/btn_selecter"
android:enabled="false"
android:text="登录"
android:textColor="@color/white"
/>
</LinearLayout>
</ScrollView>

mScrollView=(ScrollView)view.findViewById(R.id.scrollview);
usernamelogin_username.setOnTouchListener(newView.OnTouchListener(){
@Override
publicbooleanonTouch(Viewv,MotionEventevent){
changeScrollView();
returnfalse;
}
});
usernamelogin_password.setOnTouchListener(newView.OnTouchListener(){
@Override
publicbooleanonTouch(Viewv,MotionEventevent){
changeScrollView();
returnfalse;
}
});

 /**
 *使ScrollView指向底部
 */
 privatevoidchangeScrollView(){
 newHandler().postDelayed(newRunnable(){
 @Override
 publicvoidrun(){
 mScrollView.scrollTo(0,mScrollView.getHeight());
 }
 },300);
 }

<&#63;xml version="1.0" encoding="utf-8"&#63;>
<scale xmlns:android="http://schemas.android.com/apk/res/android"  
 android:fromXScale="1.0" 
 android:toXScale="0.0" 
 android:fromYScale="1.0" 
 android:toYScale="0.0" 
 android:pivotX="50%" 
 android:pivotY="50%" 
 android:duration="500" 
 android:repeatCount="0"/>

<&#63;xml version="1.0" encoding="utf-8"&#63;>
 <scale xmlns:android="http://schemas.android.com/apk/res/android" 
 android:fromXScale="0.0" 
 android:toXScale="1.0" 
 android:fromYScale="0.0" 
 android:toYScale="1.0" 
 android:pivotX="50%" 
 android:pivotY="50%" 
 android:duration="500" 
 android:repeatCount="0"/>

importandroid.os.Bundle;
importandroid.os.Handler;
importandroid.support.v7.app.AppCompatActivity;
importandroid.view.KeyEvent;
importandroid.view.MotionEvent;
importandroid.view.View;
importandroid.view.animation.Animation;
importandroid.view.animation.AnimationSet;
importandroid.view.animation.ScaleAnimation;
importandroid.widget.Button;
importandroid.widget.EditText;
importandroid.widget.ImageView;
publicclassMainActivityextendsAppCompatActivity{
privateImageViewmHead;//头部ImageView
@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHead=(ImageView)findViewById(R.id.iv_head);
finalButtonbtn=(Button)findViewById(R.id.btn_usernamelogin_dologin);
finalEditTextet_pass=(EditText)findViewById(R.id.et_usernamelogin_password);
finalEditTextet_name=(EditText)findViewById(R.id.et_usernamelogin_username);
/**
*当输入被点击
*/
et_name.setOnTouchListener(newView.OnTouchListener(){
@Override
publicbooleanonTouch(Viewv,MotionEventevent){
start();
returnfalse;
}
});
btn.setEnabled(false);
btn.setOnClickListener(newView.OnClickListener(){
@Override
publicvoidonClick(Viewv){
}
});
}
privatevoidstart(){
AnimationSetanimationSet=newAnimationSet(true);
ScaleAnimationscaleAnimation=newScaleAnimation(
1,0.1f,1,0.1f,
Animation.RELATIVE_TO_SELF,0.5f,
Animation.RELATIVE_TO_SELF,0.5f);
scaleAnimation.setDuration(500);
animationSet.addAnimation(scaleAnimation);
animationSet.setFillAfter(true);
animationSet.setFillBefore(false);
animationSet.setRepeatCount(0);//设置重复次数
mHead.startAnimation(scaleAnimation);
newHandler().postDelayed(newRunnable(){
@Override
publicvoidrun(){
mHead.setVisibility(View.GONE);
}
},500);
}
/**
*菜单、返回键响应
*/
@Override
publicbooleanonKeyDown(intkeyCode,KeyEventevent){
//TODOAuto-generatedmethodstub
if(keyCode==KeyEvent.KEYCODE_BACK){
if(mHead.getVisibility()==View.GONE){
AnimationSetanimationSet=newAnimationSet(true);
ScaleAnimationscaleAnimation=newScaleAnimation(
0.1f,1f,0.1f,1f,
Animation.RELATIVE_TO_SELF,0.5f,
Animation.RELATIVE_TO_SELF,0.5f);
scaleAnimation.setDuration(500);
animationSet.addAnimation(scaleAnimation);
animationSet.setFillAfter(true);
animationSet.setFillBefore(false);
mHead.startAnimation(scaleAnimation);
mHead.setVisibility(View.VISIBLE);
}else{
finish();
}
}
returnfalse;
 }
}