起因
看到众多大神纷纷有了自己的开源项目,于是自己琢磨着也想做一个开源项目来学习下,因为每次无聊必刷的app就是今日头条,评论简直比内容都精彩,所以我打算仿今日头条来练练手,期间也曾放弃过,也遇到很多坑,拿出来跟大家分享一下,喜欢的记得给个Star,当作是给我的鼓励和动力吧。
源码链接
https://github.com/yewei02538/TodayNews
无图言屌
第三方库
- BaseRecyclerViewAdapterHelper
- ImageLoader
- Retrofit
- RxJava
- ButterKnife
- MultipleTheme
- ColorTrackView
- Gson
- JieCaoVideoPlayer
技术要点
- 主要是一些第三方库的使用
- 首页顶部导航使用的hongyang大神的ColorTrackView然后做了一下封装来实现滑动渐变效果
- 多种Item布局展示->BaseRecyclerViewAdapterHelper
- 日夜间模式切换->MultipleTheme
- 个人中心 自定义ScrollView实现下拉图片放大
- 新闻详情我采用的是RecyclerView添加头的方式添加WebView(当然是Adapter里面添加),加载页面成功之后获取评论信息,点击评论图标滑动至评论第一条,这里我是调用
recyclerView.smoothScrollToPosition(1);
- 视频播放我使用的是JieCaoVideoPlayer,一群大牛封装的代码,底层实际使用ijkplayer,视频源均使用非正常手段获取,视频源地址分析请看我的另一篇博客手撸一个今日头条视频下载器
问题1
在使用MultipleTheme的时候唯一的缺陷就是需要在布局里面大量使用到自定义控件,这对于我们的项目而言,布局看着很冗余,也有点恶心。。我有时候就在想,那我可不可以写原生控件,然后在特定的时机来个偷梁换柱换成我们的自定义控件呢?(比如我们布局写RelativeLayout—转换成MyRelativeLayout),似乎好像是可以的。
思路1
当时想到一个最简单最快实现的方法,也就是替换,我在布局里面写原生控件,然后在用工具全局替换成我们的自定义控件,但是假如我们换了包名,那就需要重新替换,这无疑是不易扩展的,所以这个方法放弃掉
思路2
不知道大家有木有发现就是,我们在布局里面写上Button
、ImageView
、TextView
等这些控件的时候,在5.0以上运行的时候实际变成了AppCompatButton
、AppCompatImageView
、AppCompatTextView
(debug或者打印对象就可以看到实际的类型),在当我们运行的时候就这样悄无声息的给替换了,那系统又是怎么做到的?那只要找到它的实现方法,我们的问题不就迎刃而解了吗?
于是我找到系统替换的代码(以下代码全部基于Api23)
AppCompatViewInflater.Java
public final View createView(View parent, final String name, @NonNull Context context, @NonNull AttributeSet attrs, boolean inheritContext, boolean readAndroidTheme, boolean readAppTheme, boolean wrapContext) { final Context originalContext = context; if (inheritContext && parent != null) { context = parent.getContext(); } if (readAndroidTheme || readAppTheme) { context = themifyContext(context, attrs, readAndroidTheme, readAppTheme); } if (wrapContext) { context = TintContextWrapper.wrap(context); } View view = null; 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) { view = createViewFromTag(context, name, attrs); } if (view != null) { checkOnClickListener(view, attrs); } return view; }
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当我们在xml写的那些布局映射成对象的时候,都会调用到这里来转换成对应的AppCompat。
偷梁换柱的关键点我们找到了,那如何找到这个入口呢?
其实当我们加载布局的时候最终都会用LayoutInflater
来加载,所以我打算从这里入手,看源码我发现有一个接口可以利用->Factory
,这个接口有一个方法
public interface Factory { /** * Hook you can supply that is called when inflating from a LayoutInflater. * You can use this to customize the tag names available in your XML * layout files. * * <p> * Note that it is good practice to prefix these custom names with your * package (i.e., com.coolcompany.apps) to avoid conflicts with system * names. * * @param name Tag name to be inflated. * @param context The context the view is being created in. * @param attrs Inflation attributes as specified in XML file. * * @return View Newly created view. Return null for the default * behavior. */ public View onCreateView(String name, Context context, AttributeSet attrs); }
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果然功夫不负有心人,如果我们实现了这个接口,最终加载布局的时候那么就会调用onCreateView
在这里面来实现偷梁换柱替换成我们的自定义控件
ok,入口和关键代码都找到了,剩下的就是撸代码了
public class SkinFactory implements LayoutInflaterFactory { private AppCompatActivity mActivity; public SkinFactory(AppCompatActivity activity) { mActivity = activity; } @Override public View onCreateView(View parent, String name, Context context, AttributeSet attrs) { View view = null; boolean isColorUi = attrs.getAttributeBooleanValue("http://schemas.android.com/apk/res-auto", "isColorUi", false); if (!isColorUi) return delegateCreateView(parent, name, context, attrs); switch (name) { case "TextView": view = new ColorTextView(context, attrs); break; case "ImageView": view = new ColorImageView(context, attrs); Logger.i("ImageView 转换成"+view.getClass().getSimpleName()); break; case "RelativeLayout": view = new ColorRelativeLayout(context, attrs); break; case "LinearLayout": view = new ColorLinearLayout(context, attrs); break; case "View": view = new ColorView(context, attrs); break; } if (view == null) { view = delegateCreateView(parent, name, context, attrs); } return view; } private View delegateCreateView(View parent, String name, Context context, AttributeSet attrs) { AppCompatDelegate delegate = mActivity.getDelegate(); return delegate.createView(parent, name, context, attrs); }}
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这里isColorUi
做了一个标示,因为有的是不需要转换的,如果不转换,直接走系统的创建View流程
关键代码写好了,下面是入口
BaseActivity.java
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); LayoutInflaterCompat.setFactory(layoutInflater, new SkinFactory(this)); }
原本以为这样就完美的解决了,没想到又引出了下一个问题
Caused by: java.lang.IllegalStateException: A factory has already been set on this LayoutInflater at android.view.LayoutInflater.setFactory2(LayoutInflater.java:317) at android.support.v4.view.LayoutInflaterCompatLollipop.setFactory(LayoutInflaterCompatLollipop.java:28) at android.support.v4.view.LayoutInflaterCompat$LayoutInflaterCompatImplV21.setFactory(LayoutInflaterCompat.java:55) at android.support.v4.view.LayoutInflaterCompat.setFactory(LayoutInflaterCompat.java:85) at me.weyye.todaynews.base.BaseActivity.setLayoutInflaterFactory(BaseActivity.java:70) at me.weyye.todaynews.base.BaseActivity.onCreate(BaseActivity.java:60) at android.app.Activity.performCreate(Activity.java:6910) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2746) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567)
于是找到这个方法
public void setFactory(Factory factory) { if (mFactorySet) { throw new IllegalStateException("A factory has already been set on this LayoutInflater"); } if (factory == null) { throw new NullPointerException("Given factory can not be null"); } mFactorySet = true; if (mFactory == null) { mFactory = factory; } else { mFactory = new FactoryMerger(factory, null, mFactory, mFactory2); } }
当mFactorySet=true
的时候就会抛出这个错误,可是我并没有去set,那么可能是系统set了,对,没错,不然它怎么转换成AppCompat呢。
那么我只需要用反射把mFactorySet改成false就可以了
于是乎我修改了下原来的代码
BaseActivity.java
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setLayoutInflaterFactory(); } public void setLayoutInflaterFactory() { LayoutInflater layoutInflater = getLayoutInflater(); try { Field mFactorySet = LayoutInflater.class.getDeclaredField("mFactorySet"); mFactorySet.setAccessible(true); mFactorySet.set(layoutInflater, false); LayoutInflaterCompat.setFactory(layoutInflater, new SkinFactory(this)); } catch (Exception e) { e.printStackTrace(); } }
先利用反射改成false然后在设置上去,这样就不会报错了
问题2
好吧,几经周折终于完成了日夜间切换,但是当我滑动新闻列表的时候,又一个问题出来了…
当点击切换成夜间主题后,列表滑动后有的还是白天的主题,这很明显是RecyclerView
复用的问题,我的思路是当点击切换主题后清除掉复用的View,这样就不会出现这种问题。怎么清除呢?好像RecyclerView没有直接给我们方法,所以我得去源码好好看看,发现RecyclerView里面有个内部类Recycler
用来管理复用和回收的类,而且有clear
方法,
public final class Recycler { ... /** * Clear scrap views out of this recycler. Detached views contained within a * recycled view pool will remain. */ public void clear() { mAttachedScrap.clear(); recycleAndClearCachedViews(); } ...}
看代码好像是我所需要的,于是找到这个类对应的变量mRecycler
,可惜的是private并且没有get方法,那就只好反射咯~
RecyclerView recyclerView = (RecyclerView) rootView; try { Field mRecyclerField = RecyclerView.class.getDeclaredField("mRecycler"); mRecyclerField.setAccessible(true); Method clearMethod = RecyclerView.Recycler.class.getDeclaredMethod("clear"); clearMethod.setAccessible(true); clearMethod.invoke(mRecyclerField.get(recyclerView)); } catch (Exception e) { e.printStackTrace(); }
ok,成功解决!
未完待续…
TODO