Android主题切换(theme)，语种切换，动态获取自定义属性(attr)值风吹草低见牛羊-

1.开发环境：Android studio 3.4.0，kotlin实现
2.开发准备
①在values中添加资源文件【“new“ → “Values resouce file”】定义为”custom_theme_attrs“，内容如下：

<?xml version="1.0" encoding="utf-8"?> <resources> <!-- 控制app背景色 format:颜色值、资源引用 --> <attr name="custom_attr_app_bg" format="color|reference" /> <!-- 控制app标题栏背景色 format:颜色值、资源引用 --> <attr name="custom_attr_app_title_layout_bg" format="color|reference" /> <!-- 用户头像显示占位Drawable format:颜色值、资源引用 --> <attr name="custom_attr_user_photo_place_holder" format="color|reference" /> <!-- 用户昵称字体颜色 format:颜色值、资源引用 --> <attr name="custom_attr_nickname_text_color" format="color|reference" /> <!-- 用户备注字体颜色 format:颜色值、资源引用 --> <attr name="custom_attr_remark_text_color" format="color|reference" /> <!-- 用户头像显示的透明度 format:尺寸值、资源引用 --> <attr name="custom_attr_user_photo_alpha" format="dimension|reference" /> <attr name="titlebar_bg" format="color|reference"/> <attr name="titlebar_text_color" format="color|reference"/> <attr name="body_bg" format="color|reference"/> <attr name="body_text_color" format="color|reference"/> <attr name="title" format="string"/> </resources> 

②在资源文件”styles“中添加如下代码【添加主题】

<!-- 主题：白天 --> <style name="theme_day" parent="Theme.AppCompat.Light.NoActionBar"> <item name="titlebar_bg">#1EABF0</item> <item name="titlebar_text_color">#FFFFFF</item> <item name="body_bg">#F3F3F3</item> <item name="body_text_color">#333333</item> </style> <!-- 主题：夜晚 --> <style name="theme_night" parent="Theme.AppCompat.Light.NoActionBar"> <item name="titlebar_bg">#000000</item> <item name="titlebar_text_color">#FFFFFF</item> <item name="body_bg">#888888</item> <item name="body_text_color">#EAEAEA</item> </style> <!-- theme_day.chi_sim 表示继承theme_day --> <style name="theme_day.chi_sim"> <item name="title">主题配置</item> </style> <style name="theme_night.eng"> <item name="title">TopicConfig</item> </style> 

3.添加观察者接口：

package com.zjhj.maxapp.theme  interface ThemeChangeObserver { /**      * 加载当前主题      */     fun loadingCurrentTheme() /**      * 主题改变后通知      */     fun notifyThemeChanged() } 

4.在BaseActivity中实现接口

package com.zjhj.maxapp.base  import android.content.Context import android.os.Bundle import android.view.WindowManager import androidx.appcompat.app.AppCompatActivity import com.zjhj.maxapp.App import com.zjhj.maxapp.R import com.zjhj.maxapp.theme.ThemeChangeObserver import com.zjhj.maxapp.utils.L //自定义日志类 /**  * CreateTime 2020/4/2 09:10  * Author LiuShiHua  * Description：  */ abstract class BaseActivity : AppCompatActivity(), ThemeChangeObserver { private val KEY_THEME_TAG = "myThemeTag" private var isChangeTheme: Boolean = false     override fun onCreate(savedInstanceState: Bundle?) {         window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)         window.addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN) setThemeBeforeCreate() super.onCreate(savedInstanceState) setContentView() initView() initData() getData() } /**      */ private fun setThemeBeforeCreate() {         App.registerObserver(this)//将当前Acitivity注册成观察者 loadingCurrentTheme() } /**      * 加载当前主题      * 需要在super.onCreate(savedInstanceState)之前执行才会生效      */     override fun loadingCurrentTheme() {         when (getThemeTag()) { 1 -> setTheme(R.style.theme_day_chi_sim) -1 -> setTheme(R.style.theme_night_eng) }         L.d("loadingCurrentTheme:" + this::class.java) } abstract fun setContentView() abstract fun initView() abstract fun initData() abstract fun getData() /**      * 获取当前主题类型      */ protected open fun getThemeTag(): Int {         val preferences = getSharedPreferences("MaxTheme", Context.MODE_PRIVATE) return preferences.getInt(KEY_THEME_TAG, 1) } /**      * 设置主题类型      * 保存在sharedprferences中      */ protected open fun setThemeTag(tag: Int) {         L.d("setThemeTag:" + tag)         val preferences = getSharedPreferences("MaxTheme", Context.MODE_PRIVATE)         val edit = preferences.edit()         edit.putInt(KEY_THEME_TAG, tag)         edit.commit()         App.notifyByThemeChanged() } /**      * 注销这个观察者      */     override fun onDestroy() {         App.unregisterObserver(this) super.onDestroy() } } 

5.在APP（继承 Application）中管理观察者

package com.zjhj.maxapp  import android.app.Application import android.content.Context import com.zjhj.maxapp.theme.ThemeChangeObserver   /**  * CreateTime 2020/4/9 09:40  * Author LiuShiHua  * Description：  */ class App : Application() {       companion object {//静态属性或方法         lateinit var context: Context         get          private var mThemeChangeObserverStack: MutableList<ThemeChangeObserver>? = null          /**          * 获得observer堆栈          */ private fun obtainThemeChangeObserverStack(): MutableList<ThemeChangeObserver>? { if (mThemeChangeObserverStack == null) mThemeChangeObserverStack = ArrayList() return mThemeChangeObserverStack         } /**          * 向堆栈中添加observer          */         fun registerObserver(observer: ThemeChangeObserver?) { if (observer == null || obtainThemeChangeObserverStack()!!.contains(observer)) return obtainThemeChangeObserverStack()!!.add(observer) } /**          * 从堆栈中移除observer          */         fun unregisterObserver(observer: ThemeChangeObserver?) { if (observer == null || !obtainThemeChangeObserverStack()!!.contains(observer)) return obtainThemeChangeObserverStack()!!.remove(observer) } /**          * 向堆栈中所有对象发送更新UI的指令          */         fun notifyByThemeChanged() {             val observers: List<ThemeChangeObserver>? = obtainThemeChangeObserverStack() for (observer in observers!!) {                 observer.loadingCurrentTheme() //                 observer.notifyThemeChanged() // } } }      override fun onCreate() { super.onCreate()         context = this } } 

5.在BaseActivity实例中去调用更换主题

package com.zjhj.maxapp  import com.zjhj.maxapp.base.BaseActivity import kotlinx.android.synthetic.main.activity_theme.*  class ThemeActivity : BaseActivity() {     override fun setContentView() { setContentView(R.layout.activity_theme) }      override fun initView() {         changeTheme.setOnClickListener { if (getThemeTag()==1) {//设置主题 setThemeTag(-1) } else { setThemeTag(1) } recreate()//重新构建页面 } }      override fun initData() { }      override fun getData() { }      override fun notifyThemeChanged() { } } 

6.说明：网上有些建议是使用recreate()来重新构建页面就行，实际中很多Activity都无法使用recreate()来重新构建页面，或者想保存之前的页面信息而不希望页面重新构建，我这里使用的是在Activity中notifyThemeChanged中重新设置对应主题的属性值【感觉比较low】

...  override fun notifyThemeChanged() {         val typedValue = TypedValue() //获取当前主题下的titlebar_bg属性值，并赋给typedValue         theme.resolveAttribute(R.attr.titlebar_bg, typedValue, true) //设置属性值【注意：属性是那种类型，设置的时候就用成那种类型】         toolBar.setBackgroundColor(typedValue.data) } ... 

实现效果：在主题设置也改变主题后其他页面跟这变化