Android 切换应用风格，夜间模式

加入SharedPreference标志，可以记忆上次选用的风格，从而下次启动时不必重置。

package com.zms.nightstyle;

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class Main extends Activity {
    private boolean isNight = false;
    private Button btnSet;
    private Button btnGet;
    private SharedPreferences sharedPreferences;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        sharedPreferences = getSharedPreferences("UseStyle", Context.MODE_WORLD_READABLE);
        isNight = sharedPreferences.getBoolean("isNight", false);
        if (isNight) {
            this.setTheme(R.style.MyThemeNight);
        } else {
            this.setTheme(R.style.MyThemeDefault);
        }
        setContentView(R.layout.main);
        btnSet = (Button) findViewById(R.id.btnSet);
        btnGet = (Button) findViewById(R.id.btnGet);
        btnSet.setOnClickListener(new onClickListenerImp());
        btnGet.setOnClickListener(new onClickListenerImp());
    }

    class onClickListenerImp implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            if (v == btnSet) {
                Editor editor = sharedPreferences.edit();
                if (isNight) {
                    setTheme(R.style.MyThemeDefault);
                    isNight = false;
                } else {
                    setTheme(R.style.MyThemeNight);
                    isNight = true;
                }
                editor.putBoolean("isNight", isNight);
                editor.commit();

                setContentView(R.layout.main);
                btnSet = (Button) findViewById(R.id.btnSet);
                btnGet = (Button) findViewById(R.id.btnGet);
                btnSet.setOnClickListener(new onClickListenerImp());
                btnGet.setOnClickListener(new onClickListenerImp());
            } else if (v == btnGet) {
                Toast.makeText(Main.this, "isNight: " + isNight, Toast.LENGTH_SHORT).show();
            }
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <!-- 默认主题 -->
    <style name="MyThemeDefault" parent="@android:style/Theme">
        <item name="btnColor">#00ff00</item>
        <item name="mainBackground">#ffffff</item>
        <item name="mainTextColor">#000000</item>
        <item name="textString">默认主题</item>
    </style>

    <!-- 夜间主题 -->
    <style name="MyThemeNight" parent="@android:style/Theme">
        <item name="btnColor">#0000ff</item>
        <item name="mainBackground">#000000</item>
        <item name="mainTextColor">#ffffff</item>
        <item name="textString">夜间主题</item>
    </style>

</resources>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="?mainBackground"
    android:orientation="vertical">

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="?textString" />

    <ImageView
        android:id="@+id/ivBook"
        android:layout_width="62dip"
        android:layout_height="42dip"
        android:layout_gravity="center"
        android:layout_marginTop="0dip"
        android:gravity="center"
        android:src="?btnColor" />

    <Button
        android:id="@+id/btnSet"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:text="改变主题" />

    <Button
        android:id="@+id/btnGet"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:text="Get Flag" />

</LinearLayout>