Hook安卓项目内的字符串获取,用服务器的key value优先代替本地的key value

前言

前段时间接到一个需求,要动态的增加多语言语种,且可以动态更新用户app上的不规范语言(比如一个英语过长导致按钮内显示不全)

服务端的逻辑和前端动态获取的逻辑就不说了

修改app内的语言参考这篇安卓多语言设置,深渊巨坑,适配7.0以上,并且解决因WebView产生的问题

正文

首先确定一下安卓中有几种获取字符串的方式

1.Context#getResources().getString()

2.Context#getString()//其实内部还是用的上一种方式,只不过少写了一点代码

3.xml#android:text="@string/xxx"

那其实算下来只有两种,一种是通过resources来获取String,另一种是在xml解析的时候获取String

第一种:通过包装并拦截resources来Hook getString()

原理其实也很简单:

通过观察源码,发现Context每次调用getString()之前都会先调用一下getResources(),这时只要重写一下Application和BaseActivity的getResources(),返回自己包装的resources,即可拦截到getString()方法,然后通过资源id获取资源名,查找服务器返回的对应key的value,如果有就返回服务器的,没有则使用应用自身的.

至于为什么不需要重写BaseFragment和BaseDialog的,因为BaseFragment的getResources()会调用requireContext(),而requireContext()返回的Context对象就是附加到的Activity对象,所以不用设置,同理Dialog需要在构造的时候传入Activity,so

ps:既然Fragment是每次调用getString()都会调用getContext(),那这样在Fragment销毁之后就不能调用getString()了,否则就会抛异常!

代码如下:

BaseActivity为例:

    private var resources: Resources? = null

    override fun getResources(): Resources {
        if (resources == null) {
            resources = LanguageResources(super.getResources())
        }
        return resources!!
    }

资源包装类LanguageResources如下:
    /**
     * creator: lt  [e-mail]
     * 通过拦截appResources来拦截字符串
     */
    class LanguageResources(val resources: Resources)
        : Resources(resources.assets, resources.displayMetrics, resources.configuration) {

        override fun getText(id: Int): CharSequence {
            resources.getResourceEntryName(id)?.let { thisLanguageKVMap[it]?.let { return it } }
            return resources.getText(id)
        }

        override fun getText(id: Int, def: CharSequence?): CharSequence? {
            resources.getResourceEntryName(id)?.let { thisLanguageKVMap[it]?.let { return it } }
            return resources.getText(id, def)
        }

        override fun getString(id: Int): String {
            resources.getResourceEntryName(id)?.let { thisLanguageKVMap[it]?.let { return it } }
            return resources.getString(id)
        }

        override fun getString(id: Int, vararg formatArgs: Any?): String {
            resources.getResourceEntryName(id)?.let { thisLanguageKVMap[it]?.let { return it.format(*formatArgs) } }
            return resources.getString(id, *formatArgs)
        }

        override fun getTextArray(id: Int): Array<CharSequence?> {
            //项目内不要使用array
            return resources.getTextArray(id)
        }

        override fun getStringArray(id: Int): Array<String?> {
            //项目内不要使用array
            return resources.getStringArray(id)
        }

        override fun getQuantityText(id: Int, quantity: Int): CharSequence {
            return resources.getQuantityText(id, quantity)
        }

        override fun getQuantityString(id: Int, quantity: Int, vararg formatArgs: Any?): String {
            return resources.getQuantityString(id, quantity, *formatArgs)
        }

        override fun getQuantityString(id: Int, quantity: Int): String {
            return resources.getQuantityString(id, quantity)
        }

        override fun getIntArray(id: Int): IntArray {
            return resources.getIntArray(id)
        }

        override fun obtainTypedArray(id: Int): TypedArray {
            return resources.obtainTypedArray(id)
        }

        override fun getDimension(id: Int): Float {
            return resources.getDimension(id)
        }

        override fun getDimensionPixelOffset(id: Int): Int {
            return resources.getDimensionPixelOffset(id)
        }

        override fun getDimensionPixelSize(id: Int): Int {
            return resources.getDimensionPixelSize(id)
        }

        override fun getFraction(id: Int, base: Int, pbase: Int): Float {
            return resources.getFraction(id, base, pbase)
        }

        override fun getDrawable(id: Int): Drawable? {
            return resources.getDrawable(id)
        }

        @RequiresApi(21)
        override fun getDrawable(id: Int, theme: Theme?): Drawable? {
            return resources.getDrawable(id, theme)
        }

        override fun getDrawableForDensity(id: Int, density: Int): Drawable? {
            return resources.getDrawableForDensity(id, density)
        }

        @RequiresApi(21)
        override fun getDrawableForDensity(id: Int, density: Int, theme: Theme?): Drawable? {
            return resources.getDrawableForDensity(id, density, theme)
        }

        override fun getMovie(id: Int): Movie? {
            return resources.getMovie(id)
        }

        override fun getColor(id: Int): Int {
            return resources.getColor(id)
        }

        override fun getColorStateList(id: Int): ColorStateList {
            return resources.getColorStateList(id)
        }

        override fun getBoolean(id: Int): Boolean {
            return resources.getBoolean(id)
        }

        override fun getInteger(id: Int): Int {
            return resources.getInteger(id)
        }

        override fun getLayout(id: Int): XmlResourceParser {
            return resources.getLayout(id)
        }

        override fun getAnimation(id: Int): XmlResourceParser {
            return resources.getAnimation(id)
        }

        override fun getXml(id: Int): XmlResourceParser {
            return resources.getXml(id)
        }

        override fun openRawResource(id: Int): InputStream {
            return resources.openRawResource(id)
        }

        override fun openRawResource(id: Int, value: TypedValue?): InputStream {
            return resources.openRawResource(id, value)
        }

        override fun openRawResourceFd(id: Int): AssetFileDescriptor? {
            return resources.openRawResourceFd(id)
        }

        override fun getValue(id: Int, outValue: TypedValue?, resolveRefs: Boolean) {
            resources.getValue(id, outValue, resolveRefs)
        }

        override fun getValueForDensity(id: Int, density: Int, outValue: TypedValue?, resolveRefs: Boolean) {
            resources.getValueForDensity(id, density, outValue, resolveRefs)
        }

        override fun getValue(name: String?, outValue: TypedValue?, resolveRefs: Boolean) {
            resources.getValue(name, outValue, resolveRefs)
        }

        override fun obtainAttributes(set: AttributeSet?, attrs: IntArray?): TypedArray? {
            return resources.obtainAttributes(set, attrs)
        }

        override fun updateConfiguration(config: Configuration?, metrics: DisplayMetrics?) {
            if (resources == null)
                super.updateConfiguration(config, metrics)
            else
                resources.updateConfiguration(config, metrics)
        }

        override fun getDisplayMetrics(): DisplayMetrics? {
            return resources.displayMetrics
        }

        override fun getConfiguration(): Configuration? {
            return resources.configuration
        }

        override fun getIdentifier(name: String?, defType: String?, defPackage: String?): Int {
            return resources.getIdentifier(name, defType, defPackage)
        }

        override fun getResourceName(resid: Int): String? {
            return resources.getResourceName(resid)
        }

        override fun getResourcePackageName(resid: Int): String? {
            return resources.getResourcePackageName(resid)
        }

        override fun getResourceTypeName(resid: Int): String? {
            return resources.getResourceTypeName(resid)
        }

        override fun getResourceEntryName(resid: Int): String? {
            return resources.getResourceEntryName(resid)
        }

        override fun parseBundleExtras(parser: XmlResourceParser?, outBundle: Bundle?) {
            resources.parseBundleExtras(parser, outBundle)
        }

        override fun parseBundleExtra(tagName: String?, attrs: AttributeSet?, outBundle: Bundle?) {
            resources.parseBundleExtra(tagName, attrs, outBundle)
        }

        @RequiresApi(Build.VERSION_CODES.M)
        override fun getColor(id: Int, theme: Theme?): Int {
            return resources.getColor(id, theme)
        }

        @RequiresApi(Build.VERSION_CODES.M)
        override fun getColorStateList(id: Int, theme: Theme?): ColorStateList {
            return resources.getColorStateList(id, theme)
        }

        @RequiresApi(Build.VERSION_CODES.O)
        override fun getFont(id: Int): Typeface {
            return resources.getFont(id)
        }

        @RequiresApi(Build.VERSION_CODES.Q)
        override fun getFloat(id: Int): Float {
            return resources.getFloat(id)
        }
    }

简单解释一下:resources.getResourceEntryName()是通过id获取对应的资源名,thisLanguageKVMap是从服务端获取的多语言键值对HashMap(因为查找快),而我没有拦截getStringArray()和getTextArray()是因为项目内只有一个地方用了,且多语言不好搞,且实现方式不同,我就给改成getString()的形式懒得去研究它了

ps:不能混淆资源名(腾讯的一个混淆资源框架),否则该方案无效

pps:顺便吐槽一下,为啥kotlin的类委托只支持接口,不支持类..好坑,多写了一堆模板代码

第二种:通过拦截xml解析来Hook @string/

最开始我通过参考TextView的text获取逻辑,然后找到TypedArray#getText(),然后发现传进去的是个index,然后各种乱七八糟不熟悉的东西快给我绕晕了,果断使用其他方案

然后我想起来前两年有个很火的快捷开发的方案,通过拦截View生成来在xml中写shape,当时我也模仿写了个ShapeAndSelectUtil,用到的原理也是拦截LayoutInflater.Factory2,正好能用这个来拦截xml解析

原理:

通过拦截View的创建过程,拿到会用到@string/的View的对象(比如TextView和EditText或自定义View),获取对应的id并重新从key value中获取和设置

代码如下:

//在BaseActivity的onCreate()中的super.onCreate()之前调用
layoutInflater.factory2 = LanguageLayoutInflaterFactory(this)


/**
 * creator: lt  [e-mail]
 */
class LanguageLayoutInflaterFactory(val activity: Activity) : LayoutInflater.Factory2 {
    private val APP_KEY = "http://schemas.android.com/apk/res-auto"
    private val ANDROID_KEY = "http://schemas.android.com/apk/res/android"

    //sdk的activity使用的布局生成器
    private val delegate: AppCompatDelegate by lazy(LazyThreadSafetyMode.NONE) { AppCompatDelegate.create(activity, null) }

    //获取默认的createView方法,可以在这里判断并适配换肤框架等
    fun checkAndCreateView(parent: View?, name: String?, context: Context, attrs: AttributeSet): View? {
        return when (activity) {
            is AppCompatActivity -> activity.delegate.createView(parent, name, context, attrs)
            else -> delegate.createView(parent, name, context, attrs)
        }
    }

    override fun onCreateView(parent: View?, name: String, context: Context, attrs: AttributeSet): View? {
        return checkAndReturnView(name, context, attrs, checkAndCreateView(parent, name, context, attrs))
    }

    override fun onCreateView(name: String, context: Context, attrs: AttributeSet): View? {
        return null
    }

    fun checkAndReturnView(name: String, context: Context, attrs: AttributeSet, view: View?): View? {
        val view = view ?: try {
            createViewGroup(name, context, attrs)
        } catch (e: Exception) {
            e.toString().e()
            null
        } ?: return null

        handlerXmlText(view, attrs)
        return view
    }

    private fun handlerXmlText(view: View, attrs: AttributeSet) {
        if (view is TextView) {
            val value = getStringValue(attrs, true, "text")
            if (value != null)
                view.text = value
        }
        if (view is EditText) {
            val value = getStringValue(attrs, true, "hint")
            if (value != null)
                view.hint = value
        }
        //下面两个是自定义View使用了@string/
        if (view is ItemView) {
            val value = getStringValue(attrs, false, "left_text")
            if (value != null)
                view.setLeftText(value)
        }
        if (view is SelectView) {
            val value = getStringValue(attrs, false, "middle_text")
            if (value != null)
                view.setMiddleText(value)
        }
        //或者下面这种写法
        /*if (view is TextView)
            getStringValue(attrs, true, "text")?.let(view::setText)
        if (view is EditText)
            getStringValue(attrs, true, "hint")?.let(view::setHint)
        if (view is ItemView)
            getStringValue(attrs, false, "left_text")?.let(view::setLeftText)
        if (view is SelectView)
            getStringValue(attrs, false, "middle_text")?.let(view::setMiddleText)*/
    }

    private fun Int.toText() = activity.getString(this)

    private fun getStringValue(attrs: AttributeSet, isAndroidSystem: Boolean, valueName: String): String? {
        val value = attrs.getAttributeValue(if (isAndroidSystem) ANDROID_KEY else APP_KEY, valueName)
        if (value?.startsWith("@") == true)
            try {
                return value.substring(1).toIntOrNull()?.toText()
            } catch (e: Exception) {
                e.upload()
            }
        return null
    }

    private fun createViewGroup(name: String, context: Context, attrs: AttributeSet): View? {
        return when (name) {
            //下面两个是自定义View使用了@string/
            //且下面两个是ViewGroup,如果是View则会在delegate中就创建完成
            "com.xxx.ItemView" -> ItemView(context, attrs)
            "com.xxx.SelectView" -> SelectView(context, attrs)
            else -> null
        }
    }
}

最后把两种方式一块使用,然后就ok了(应该不会有人只用xml或只用getString()吧)

扩展

多语言使用过程中可能会遇见类似阿拉伯语的从右往左的习惯,其文字也是从右往左看的,这时需要将类似paddingLeft和paddingRight改成paddingStart和paddingEnd,更多的多语言适配可以参考安卓官网:https://developer.android.com/training/basics/supporting-devices/languages?hl=zh-cn#kotlin

然后获取是否是从左到右的api:

    fun isLTR(context: Context): Boolean {
        return context.resources.configuration.layoutDirection == View.LAYOUT_DIRECTION_LTR
    }

 

end

本文地址：https://blog.csdn.net/qq_33505109/article/details/112212969