不只是切换多语言Android（一）

前言：前几天在地铁上看到一哥们的一篇app换肤方案解决，觉得很nice，于是就研究了一下，收获蛮多，还想到以前我做过的app，当时是需要中英文切换的，于是打算把这哥们的换肤方案运用在切换语言上去，捣腾了一会，感觉还可以，但是自我感觉还是不太理想，不管咋样，就当涨涨见识呗，于是打算把我所学到的知识分享给大家，大家有什么好的切换语言方案记得告知一下哈，先拜谢啦！！

先附上大牛的换肤demo地址：
https://github.com/ximsfei/Android-skin-support

先看一下换肤效果：

然后根据换肤思路，看看我们实现的切换语言框架效果：

其中主要的思路还是来自v7的AppCompatActivity，AppCompatActivity做的一件事就是把我们的基本组件转换成了material效果组件，我们简单的看一下AppCompatActivity是怎么处理的。

public class AppCompatActivity extends FragmentActivity implements AppCompatCallback,        TaskStackBuilder.SupportParentable, ActionBarDrawerToggle.DelegateProvider {    。。。。     @Override    protected void onCreate(@Nullable Bundle savedInstanceState) {        final AppCompatDelegate delegate = getDelegate();        delegate.installViewFactory();        delegate.onCreate(savedInstanceState);    }    。。。。｝

首先创建了一个AppCompatDelegate对象delegate：

 /**     * @return The {@link AppCompatDelegate} being used by this Activity.     */    @NonNull    public AppCompatDelegate getDelegate() {        if (mDelegate == null) {            mDelegate = AppCompatDelegate.create(this, this);        }        return mDelegate;    }

然后我们看看它是怎么创建mDelegate对象的：

private static AppCompatDelegate create(Context context, Window window,            AppCompatCallback callback) {        final int sdk = Build.VERSION.SDK_INT;        if (BuildCompat.isAtLeastN()) {            return new AppCompatDelegateImplN(context, window, callback);        } else if (sdk >= 23) {            return new AppCompatDelegateImplV23(context, window, callback);        } else if (sdk >= 14) {            return new AppCompatDelegateImplV14(context, window, callback);        } else if (sdk >= 11) {            return new AppCompatDelegateImplV11(context, window, callback);        } else {            return new AppCompatDelegateImplV9(context, window, callback);        }    }

找到了delegate对象，我们反过来看看AppCompatActivity最初的oncreate方法：

@Override    protected void onCreate(@Nullable Bundle savedInstanceState) {        final AppCompatDelegate delegate = getDelegate();        delegate.installViewFactory();        delegate.onCreate(savedInstanceState);

我们找到installViewFactory方法：

@Override    public void installViewFactory() {        LayoutInflater layoutInflater = LayoutInflater.from(mContext);        if (layoutInflater.getFactory() == null) {            LayoutInflaterCompat.setFactory(layoutInflater, this);        } else {            if (!(LayoutInflaterCompat.getFactory(layoutInflater)                    instanceof AppCompatDelegateImplV9)) {                Log.i(TAG, "The Activity's LayoutInflater already has a Factory installed"                        + " so we can not install AppCompat's");            }        }    }

可以看到在delegate的内部，获取到当前app的 layoutInflater对象，然后给layoutInflater设置了一个factory：

  LayoutInflater layoutInflater = LayoutInflater.from(mContext);        if (layoutInflater.getFactory() == null) {            LayoutInflaterCompat.setFactory(layoutInflater, this);        } 

LayoutInflater我们都不陌生，当我们去加载一个xml布局的时候用到：

inflater.inflate(xxxx)

这个方法：

我们顺着这个方法往下走：

        getLayoutInflater().inflate()

ublic View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {。。省略很多代码                            rInflate(parser, root, inflaterContext, attrs, false);。。省略很多代码｝

我们看看rInflate方法：

void rInflate(XmlPullParser parser, View parent, Context context,            AttributeSet attrs, boolean finishInflate) throws XmlPullParserException, IOException {        final int depth = parser.getDepth();        int type;        while (((type = parser.next()) != XmlPullParser.END_TAG ||                parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {            if (type != XmlPullParser.START_TAG) {                continue;            }            final String name = parser.getName();            if (TAG_REQUEST_FOCUS.equals(name)) {                parseRequestFocus(parser, parent);            } else if (TAG_TAG.equals(name)) {                parseViewTag(parser, parent, attrs);            } else if (TAG_INCLUDE.equals(name)) {                if (parser.getDepth() == 0) {                    throw new InflateException("<include /> cannot be the root element");                }                parseInclude(parser, context, parent, attrs);            } else if (TAG_MERGE.equals(name)) {                throw new InflateException("<merge /> must be the root element");            } else {                final View view = createViewFromTag(parent, name, context, attrs);                final ViewGroup viewGroup = (ViewGroup) parent;                final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);                rInflateChildren(parser, view, attrs, true);                viewGroup.addView(view, params);            }        }        if (finishInflate) {            parent.onFinishInflate();        }    }

我们继续看到其中的createViewFromTag方法：

 View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,            boolean ignoreThemeAttr) {            。。。。     if (view == null && mPrivateFactory != null) {                view = mPrivateFactory.onCreateView(parent, name, context, attrs);            }            。。。。    }

这个mPrivateFactory就是我们在AppCompatActivity的onCreate方法中调用的：

        delegate.installViewFactory();

@Override    public void installViewFactory() {        LayoutInflater layoutInflater = LayoutInflater.from(mContext);        if (layoutInflater.getFactory() == null) {            LayoutInflaterCompat.setFactory(layoutInflater, this);        } else {            if (!(LayoutInflaterCompat.getFactory(layoutInflater)                    instanceof AppCompatDelegateImplV9)) {                Log.i(TAG, "The Activity's LayoutInflater already has a Factory installed"                        + " so we can not install AppCompat's");            }        }    }

所以这个factory即为AppCompatActivity中的delegate，所以当我们调用setContentView的时候，其中在PhoneWindow中会去获取app的inflator对象，然后调用inflate方法，把通过我们传递的layoutid加载layout文件，在inflater方法中，当inflator设置了factory的话就会执行：

 if (view == null && mPrivateFactory != null) {                view = mPrivateFactory.onCreateView(parent, name, context, attrs);            }

所以会触发factory的onCreateView方法，把需要创建view的父类、名字、attrs属性传递过去：

比如下面的xml中view，就会传递name＝TextView、attrs为text等属性。

<TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/change_succ"        />

我们看看AppCompatActivity中的delegate对象（factory）怎么处理的：

@Override    public final View onCreateView(View parent, String name,            Context context, AttributeSet attrs) {        // First let the Activity's Factory try and inflate the view        final View view = callActivityOnCreateView(parent, name, context, attrs);        if (view != null) {            return view;        }        // If the Factory didn't handle it, let our createView() method try        return createView(parent, name, context, attrs);    }

@Override    public View createView(View parent, final String name, @NonNull Context context,            @NonNull AttributeSet attrs) {        final boolean isPre21 = Build.VERSION.SDK_INT < 21;        if (mAppCompatViewInflater == null) {            mAppCompatViewInflater = new AppCompatViewInflater();        }        // We only want the View to inherit its context if we're running pre-v21        final boolean inheritContext = isPre21 && shouldInheritContext((ViewParent) parent);        return mAppCompatViewInflater.createView(parent, name, context, attrs, inheritContext,                isPre21, /* Only read android:theme pre-L (L+ handles this anyway) */                true, /* Read read app:theme as a fallback at all times for legacy reasons */                VectorEnabledTintResources.shouldBeUsed() /* Only tint wrap the context if enabled */        );    }

最后看看
mAppCompatViewInflater.createView：

         @NonNull AttributeSet attrs, boolean inheritContext,            boolean readAndroidTheme, boolean readAppTheme, boolean wrapContext) {        final Context originalContext = context;        // We can emulate Lollipop's android:theme attribute propagating down the view hierarchy        // by using the parent's context        if (inheritContext && parent != null) {            context = parent.getContext();        }        if (readAndroidTheme || readAppTheme) {            // We then apply the theme on the context, if specified            context = themifyContext(context, attrs, readAndroidTheme, readAppTheme);        }        if (wrapContext) {            context = TintContextWrapper.wrap(context);        }        View view = null;        // We need to 'inject' our tint aware Views in place of the standard framework versions        switch (name) {            case "TextView":                view = new AppCompatTextView(context, attrs);                break;            case "ImageView":                view = new AppCompatImageView(context, attrs);                break;            case "Button":                view = new AppCompatButton(context, attrs);                break;            case "EditText":                view = new AppCompatEditText(context, attrs);                break;            case "Spinner":                view = new AppCompatSpinner(context, attrs);                break;            case "ImageButton":                view = new AppCompatImageButton(context, attrs);                break;            case "CheckBox":                view = new AppCompatCheckBox(context, attrs);                break;            case "RadioButton":                view = new AppCompatRadioButton(context, attrs);                break;            case "CheckedTextView":                view = new AppCompatCheckedTextView(context, attrs);                break;            case "AutoCompleteTextView":                view = new AppCompatAutoCompleteTextView(context, attrs);                break;            case "MultiAutoCompleteTextView":                view = new AppCompatMultiAutoCompleteTextView(context, attrs);                break;            case "RatingBar":                view = new AppCompatRatingBar(context, attrs);                break;            case "SeekBar":                view = new AppCompatSeekBar(context, attrs);                break;        }        if (view == null && originalContext != context) {            // If the original context does not equal our themed context, then we need to manually            // inflate it using the name so that android:theme takes effect.            view = createViewFromTag(context, name, attrs);        }        if (view != null) {            // If we have created a view, check it's android:onClick            checkOnClickListener(view, attrs);        }        return view;    }

好吧，看到这里是不是有点兴奋呢？？我们看到，当我们在xml布局中创建一些基本的组件的时候，都会AppCompatActivity转换成了AppCompatTextView等等这类的组件了，好累啊～AppCompatTextView我就不看了，AppCompatTextView等就是实现material属性的关键组件。

好啦～～也不知道小伙伴看懂了没有，简单总结一下：

比如我们在xml中创建一个TextView—>我们调用activity的setcontentview—>inflater的inflate方法－－－>在AppCompatActivity方法中给inflater设置factory－－－>调用inflater的factory的oncreateview方法—>然后在oncreateview方法中通过传递的组件name创建对应的组件AppCompatTextView－－>根据activity的主题修改AppCompatTextView样式。

换肤方案的实现：

跟AppCompatActivity一样，给inflater设置一个factory－－－>>调用inflater的factory的oncreateview方法－－－>然后在oncreateview方法中通过传递的组件name创建对应的组件SkinAbleTextView－－－>然后把创建的SkinAbleTextView组件用一个集合装起来—>最后通过观察者模式，当变皮肤的时候，遍历所有的组件，然后调用对应的换肤方法－－－>改变样式

我们的切换语言框架也是一样哈～～～我就不啰嗦了，下节直接撸代码了～

不只是切换多语言Android（二）

本节先到这里！！
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