Android Them+SharedPreferences 修改程序所有view字体颜色、大小和页面背景

有这么一个需求，可以对页面的样式进行选择，然后根据选择改变程序所有字体颜色和页面背景。同时下一次启动程序，当前设置依然有效。

根据需求，我们需要一种快速，方便，有效的方式来实现需求，然后可以通过Android Them + SharedPreferences 来实现需求。Them用于存放设置的每一种样式，并应用于程序中，SharedPreferences用于记住程序当前的样式，根据SharedPreferences的内容来设置程序的样式，实现下次启动能够oncreat当前的样式设置。

这里的Them比较简单，只是定义了字体颜色和页面背景颜色。在res/values/styles.xml 文件中增加Them主题

    <style name="FirstThem">
        <item name="android:textColor">@color/FirstThemTextColor</item> <!-- 字体颜色  -->
        <item name="android:windowBackground">@color/FirstThemBackgroundColor</item> <!-- 窗口背景 -->
    </style>
    
    <style name="SecondThem">
        <item name="android:textColor">@color/SecondThemTextColor</item> <!-- 字体颜色  -->
        <item name="android:windowBackground">@color/SecondThemBackgroundColor</item> <!-- 窗口背景 -->
    </style>
    
    <style name="ThirdThem">
        <item name="android:textColor">@color/ThirdThemTextColor</item> <!-- 字体颜色  -->
        <item name="android:windowBackground">@color/ThirdThemBackgroundColor</item> <!-- 窗口背景 -->
    </style>

然后在MainActivity.java中创建SharedPreferences来记录样式的状态

    private void SharePreference() {
        sharePrefences=this.getSharedPreferences("config",Context.MODE_WORLD_READABLE
                | Context.MODE_WORLD_WRITEABLE);
        editor=sharePrefences.edit();
        boolean isThem = sharePrefences.getBoolean("isThem", false);
        int Them = sharePrefences.getInt("Them",0);//config不存在时返回0
        if(isThem){
            if(Them==1){
                setTheme(R.style.FirstThem);
            }else if(Them==2){
                setTheme(R.style.SecondThem);
            }else if(Them==3){
                setTheme(R.style.ThirdThem);
            }
        }else{//sharePrefences不存在是使用默认主题
            setTheme(R.style.FirstThem);
        }
        }

有两个比较值得注意的地方是：

1、设置主题时，setTheme(R.style.FirstThem);一定要放在setContentView(R.layout.activity_main);前，否则无效。

setTheme(R.style.FirstThem);
setContentView(R.layout.activity_main);

2、要所有页面的字体颜色和背景能够根据Them去改变，那么布局文件中的目标控件都不能设置android:textcolor,以及android:background.否则控件的android:textcolor，android:background属性会将Them的设置覆盖。

下面是一个demo的完整代码：

activity_main.xml

<LinearLayout 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:orientation="vertical"
    >

<Button 
    android:id="@+id/FirstThem"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="样式一"
    />

<Button 
    android:id="@+id/SecondThem"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="样式二"
    />

<Button 
    android:id="@+id/ThirdThem"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="样式三"
    />

<TextView 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="50dp"
    android:textSize="30sp"
    android:text="ABCDEFG"
    />

</LinearLayout>

MainActivity.java

public class MainActivity extends Activity implements OnClickListener {
    private Button FirstThemButton;
    private Button SecondThemButton;
    private Button ThirdThemButton;
    private SharedPreferences sharePrefences;
    private Editor editor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        SharePreference();
        setContentView(R.layout.activity_main);
        InitView();
        FirstThemButton=(Button) findViewById(R.id.FirstThem);
        SecondThemButton=(Button) findViewById(R.id.SecondThem);
        SecondThemButton=(Button) findViewById(R.id.ThirdThem);
    }

    private void SharePreference() {
        sharePrefences=this.getSharedPreferences("config",Context.MODE_WORLD_READABLE
                | Context.MODE_WORLD_WRITEABLE);
        editor=sharePrefences.edit();
        boolean isThem = sharePrefences.getBoolean("isThem", false);
        int Them = sharePrefences.getInt("Them",0);//config不存在时返回0
        if(isThem){
            if(Them==1){
                setTheme(R.style.FirstThem);
            }else if(Them==2){
                setTheme(R.style.SecondThem);
            }else if(Them==3){
                setTheme(R.style.ThirdThem);
            }
        }else{//sharePrefences不存在是使用默认主题
            setTheme(R.style.FirstThem);
        }
        }

    private void InitView() {
        FirstThemButton=(Button) findViewById(R.id.FirstThem);
        SecondThemButton=(Button) findViewById(R.id.SecondThem);
        ThirdThemButton=(Button) findViewById(R.id.ThirdThem);
        FirstThemButton.setOnClickListener(this);
        SecondThemButton.setOnClickListener(this);
        ThirdThemButton.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.FirstThem:
            editor.putBoolean("isThem", true);
            editor.putInt("Them", 1);
            editor.commit();
            Intent intent1=new Intent(this,MainActivity.class);
            startActivity(intent1);
            break;
        case R.id.SecondThem:
            editor.putBoolean("isThem", true);
            editor.putInt("Them",2);
            editor.commit();
            Intent intent2=new Intent(this,MainActivity.class);
            startActivity(intent2);
            break;
        case R.id.ThirdThem:
            editor.putBoolean("isThem", true);
            editor.putInt("Them", 3);
            editor.commit();
            Intent intent3=new Intent(this,MainActivity.class);
            startActivity(intent3);
            break;
        default:
            break;
        }
        
    }
    
    
}

styles.xml

<resources>

    <!--
        Base application theme, dependent on API level. This theme is replaced
        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
    -->
    <style name="AppBaseTheme" parent="Theme.AppCompat.Light">
        <!--
            Theme customizations available in newer API levels can go in
            res/values-vXX/styles.xml, while customizations related to
            backward-compatibility can go here.
        -->
    </style>

    <!-- Application theme. -->
    <style name="AppTheme" parent="AppBaseTheme">
        <!-- All customizations that are NOT specific to a particular API-level can go here. -->
    </style>
    
    <style name="FirstThem">
        <item name="android:textColor">@color/FirstThemTextColor</item> <!-- 字体颜色  -->
        <item name="android:windowBackground">@color/FirstThemBackgroundColor</item> <!-- 窗口背景 -->
    </style>
    
    <style name="SecondThem">
        <item name="android:textColor">@color/SecondThemTextColor</item> <!-- 字体颜色  -->
        <item name="android:windowBackground">@color/SecondThemBackgroundColor</item> <!-- 窗口背景 -->
    </style>
    
    <style name="ThirdThem">
        <item name="android:textColor">@color/ThirdThemTextColor</item> <!-- 字体颜色  -->
        <item name="android:windowBackground">@color/ThirdThemBackgroundColor</item> <!-- 窗口背景 -->
    </style>

</resources>

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="FirstThemTextColor">#000000</color>
    <color name="FirstThemBackgroundColor">#FFFFFF</color>
    <color name="SecondThemTextColor">#AAAAAA</color>
    <color name="SecondThemBackgroundColor">#EEBBEE</color>
    <color name="ThirdThemTextColor">#CCCCCC</color>
    <color name="ThirdThemBackgroundColor">#AAAADD</color>
</resources>