夜间模式 （文字不改变）

package com.chenke.night;

import java.nio.MappedByteBuffer;

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.Menu;
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{
    private WindowManager wm;
    private View myView;
    private Button night;
    private SharedPreferences sp;
    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);
        wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        setContentView(R.layout.activity_main);
        
        
        sp = this.getSharedPreferences("skinchange", Context.MODE_PRIVATE);
        night = (Button) findViewById(R.id.btn_dayAndnight);
        String mode = sp.getString("skin", "");
        if(mode!=null||!mode.equals("")){
            if(mode.equals(NIGHT)){
                night();
            }else{
                day();
            }
        }
        night.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                if(flage%2==0){
                    night();
                    night.setText("白天模式");
                    night.setTextColor(Color.WHITE);
                    flage++;
                }else{
                    day();
                    night.setText("夜间模式");
                    night.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);
        }
        wm.addView(myView, params);
        Editor edit = sp.edit();
        edit.putString("skin", NIGHT);
        edit.commit();
    }

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