代码如下：

package org.david.dayandnightdemo.cor;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.graphics.Color;
import android.graphics.PixelFormat;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.view.WindowManager.LayoutParams;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener {

    private WindowManager mWindowManager;
    private View myView;
    private Button btn_dayAndnight;
    private SharedPreferences skinSp;
    private final static String DAY = "day";
    private final static String NIGHT = "night";
    private int flage = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        setContentView(R.layout.activity_main);
        init();
    }

    private void init() {
        skinSp = this.getSharedPreferences("skinchange", Context.MODE_PRIVATE);
        btn_dayAndnight = (Button) findViewById(R.id.btn_dayAndnight);
        btn_dayAndnight.setOnClickListener(this);

        String mode = skinSp.getString("skin", "");
        if(mode!=null||!mode.equals("")){
            if(mode.equals(NIGHT)){
                night();
            }else{
                day();
            }
        }

    }

    @Override
    public void onClick(View v) {
        if(flage%2==0){
            night();
            btn_dayAndnight.setText("白天模式");
            btn_dayAndnight.setTextColor(Color.WHITE);
            flage++;
        }else{
            day();
            btn_dayAndnight.setText("夜间模式");
            btn_dayAndnight.setTextColor(Color.BLACK);
            flage++;
        }
    }

    public void night() {
        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT,
                LayoutParams.TYPE_APPLICATION,
                WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
                        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
        params.gravity=Gravity.BOTTOM;
        params.y=10;
        if(myView==null){
            myView=new TextView(this);
            myView.setBackgroundColor(0x80000000);
        }
        mWindowManager.addView(myView, params);
        Editor edit = skinSp.edit();
        edit.putString("skin", NIGHT);
        edit.commit();
    }

    public void day(){
        if(myView!=null){
            mWindowManager.removeView(myView);
            Editor edit = skinSp.edit();
            edit.putString("skin", DAY);
            edit.commit();
        }
    }

   
    public void removeSkin(){
        if(myView!=null){
            mWindowManager.removeView(myView);
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        String mode = skinSp.getString("skin", "");
        if(mode.equals(NIGHT)){
            removeSkin();           
        }
    }

}

布局文件
代码如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/btn_dayAndnight"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/btn_changeskin" />

</RelativeLayout>