日夜间模式的切换

看了网上那么多日夜间模式切换的方法，大概来说就3种吧！不过最好的一种便是通过反射来实现~
参考链接：http://yuqirong.me/2016/09/08/对于Android日夜间模式实现的探讨/

1：在values文件夹下的colors.xml里添加：

<color name="textColor">#3b3b3b</color>
<color name="textColor_night">#FFFFFF</color>
<color name="backgroundColor">#FFFFFF</color>
<color name="backgroundColor_night">#3b3b3b</color>

2：创建Theme管理类

package com.example.administrator.demo.view;

import android.content.Context;
import android.content.res.Resources;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;

public class ThemeManager {
    // 默认是日间模式
    private static ThemeMode mThemeMode = ThemeMode.DAY;
    // 主题模式监听器
    private static List<OnThemeChangeListener> mThemeChangeListenerList = new LinkedList<>();
    // 夜间资源的缓存，key : 资源类型, 值<key:资源名称, value:int值>
    private static HashMap<String, HashMap<String, Integer>> sCachedNightResrouces = new HashMap<>();
    // 夜间模式资源的后缀，比如日件模式资源名为：R.color.activity_bg, 那么夜间模式就为 ：R.color.activity_bg_night
    private static final String RESOURCE_SUFFIX = "_night";

    /**
     * 主题模式，分为日间模式和夜间模式
     */
    public enum ThemeMode {
        DAY, NIGHT
    }

    /**
     * 设置主题模式
     */
    public static void setThemeMode(ThemeMode themeMode) {
        if (mThemeMode != themeMode) {
            mThemeMode = themeMode;
            if (mThemeChangeListenerList.size() > 0) {
                for (OnThemeChangeListener listener : mThemeChangeListenerList) {
                    listener.onThemeChanged();
                }
            }
        }
    }

    /**
     * 根据传入的日间模式的resId得到相应主题的resId，注意：必须是日间模式的resId
     * 日间模式的resId
     * 相应主题的resId，若为日间模式，则得到dayResId；反之夜间模式得到nightResId
     */
    public static int getCurrentThemeRes(Context context, int dayResId) {
        if (getThemeMode() == ThemeMode.DAY) {
            return dayResId;
        }
        // 资源名
        String entryName = context.getResources().getResourceEntryName(dayResId);
        // 资源类型
        String typeName = context.getResources().getResourceTypeName(dayResId);
        HashMap<String, Integer> cachedRes = sCachedNightResrouces.get(typeName);
        // 先从缓存中去取，如果有直接返回该id
        if (cachedRes == null) {
            cachedRes = new HashMap<>();
        }
        Integer resId = cachedRes.get(entryName + RESOURCE_SUFFIX);
        if (resId != null && resId != 0) {
            return resId;
        } else {
            //如果缓存中没有再根据资源id去动态获取
            try {
                // 通过资源名，资源类型，包名得到资源int值
                int nightResId = context.getResources().getIdentifier(entryName + RESOURCE_SUFFIX, typeName, context.getPackageName());
                // 放入缓存中
                cachedRes.put(entryName + RESOURCE_SUFFIX, nightResId);
                sCachedNightResrouces.put(typeName, cachedRes);
                return nightResId;
            } catch (Resources.NotFoundException e) {
                e.printStackTrace();
            }
        }
        return 0;
    }

    /**
     * 注册ThemeChangeListener
     */
    public static void registerThemeChangeListener(OnThemeChangeListener listener) {
        if (!mThemeChangeListenerList.contains(listener)) {
            mThemeChangeListenerList.add(listener);
        }
    }

    /**
     * 反注册ThemeChangeListener
     */
    public static void unregisterThemeChangeListener(OnThemeChangeListener listener) {
        if (mThemeChangeListenerList.contains(listener)) {
            mThemeChangeListenerList.remove(listener);
        }
    }

    /**
     * 得到主题模式
     */
    public static ThemeMode getThemeMode() {
        return mThemeMode;
    }

    /**
     * 主题模式切换监听器
     */
    public interface OnThemeChangeListener {
        /**
         * 主题切换时回调
         */
        void onThemeChanged();
    }
}

3：Activity中使用

package com.example.administrator.demo.activity;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;

import com.example.administrator.demo.R;
import com.example.administrator.demo.view.ThemeManager;

public class MainActivity extends Activity implements ThemeManager.OnThemeChangeListener{
    private Button day_night_mode;
    private RelativeLayout relativeLayout;
    private boolean isDay = true;//默认是日间模式
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ThemeManager.registerThemeChangeListener(this);
        day_night_mode = (Button) findViewById(R.id.day_night_mode);
        relativeLayout = (RelativeLayout) findViewById(R.id.relativeLayout);
        day_night_mode.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(isDay==true){
                    ThemeManager.setThemeMode(ThemeManager.ThemeMode.NIGHT );
                    day_night_mode.setText("日间模式");
                    isDay=false;
                }else {
                    ThemeManager.setThemeMode(ThemeManager.ThemeMode.DAY );
                    day_night_mode.setText("夜间模式");
                    isDay=true;
                }
            }
        });
    }

    @Override
    public void onThemeChanged() {
        //日间模式下的颜色
        day_night_mode.setTextColor(getResources().getColor(ThemeManager.getCurrentThemeRes(MainActivity.this, R.color.textColor)));
        relativeLayout.setBackgroundColor(getResources().getColor(ThemeManager.getCurrentThemeRes(MainActivity.this, R.color.backgroundColor)));
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ThemeManager.unregisterThemeChangeListener(this);
    }
}