安卓 简单的遮罩层

<?xml version="1.0" encoding="utf-8"?>  
        <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"  
            android:id="@+id/layout"  
            android:layout_width="fill_parent"  
            android:layout_height="fill_parent"   
            android:background="#fff">  
            <RelativeLayout  
                android:layout_width="fill_parent"  
                android:layout_height="wrap_content"  
                android:layout_gravity="bottom"  
                android:background="#86222222"  
                android:orientation="horizontal" >  
          
                <TextView  
                    android:id="@+id/titleTextView"  
                    android:layout_width="wrap_content"  
                    android:layout_height="wrap_content"  
                    android:text="遮罩效果"  
                    android:textColor="#ff0000" />  
          
                <Button  
                    android:id="@+id/unfoldButton"  
                    android:layout_width="wrap_content"  
                    android:layout_height="wrap_content"  
                    android:layout_alignParentRight="true"  
                    android:text="显示遮罩" />  
            </RelativeLayout>  
          
        </FrameLayout> 

public class ShadeActivity extends Activity {  
        // 设置是否展开  
        private boolean isFolded = true;  
        // 设置控件  
        private FrameLayout layout = null;  
        private Button unfoldButton = null;  
        private TextView textView = null;  
      
        public void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            requestWindowFeature(Window.FEATURE_NO_TITLE);  
            setContentView(R.layout.activity_shade);  
      
            initView();  
        }  
      
        @Override  
        protected void onResume() {  
            // TODO Auto-generated method stu  
            super.onResume();  
            isFolded = true;  
        }  
      
        // 初始化  
        private void initView() {  
            layout = (FrameLayout) findViewById(R.id.layout);  
            unfoldButton = (Button) findViewById(R.id.unfoldButton);  
            unfoldButton.setOnClickListener(new UnfoldClickListener());  
        }  
      
        // 按钮监听，展开一个透明的显示文本的遮挡层  
        private class UnfoldClickListener implements OnClickListener {  
            public void onClick(View v) {  
                if (isFolded) {  
                    textView = new TextView(ShadeActivity.this);  
                    textView.setTextColor(Color.BLUE);  
                    textView.setTextSize(20);  
                    textView.setText("滚滚长江东逝水，浪花淘尽英雄。\n" + "是非成败转头空，\n"  
                            + "青山依旧在，几度夕阳红。\n" + "白发渔樵江渚上，惯看秋月春风。 \n"  
                            + "一壶浊酒喜相逢，\n" + "古今多少事，都付笑谈中。");  
                    textView.setGravity(Gravity.CENTER);  
                    textView.setLayoutParams(new ViewGroup.LayoutParams(  
                            ViewGroup.LayoutParams.FILL_PARENT,  
                            ViewGroup.LayoutParams.FILL_PARENT));  
                    textView.setBackgroundColor(Color.parseColor("#86222222"));  
      
                    unfoldButton.setText("取消遮罩");  
      
                    isFolded = false;  
      
                    layout.addView(textView);  
                } else {  
                    unfoldButton.setText("显示遮罩");  
                    isFolded = true;  
                    layout.removeView(textView);  
                }  
            }  
        }  
    }