LayoutInflater源码分析

LayoutInflater.from(mContext).inflate(mLayoutId,parent,false);

1.1 LayoutInflater.from(mContext)源码分析

    /**
     * Obtains the LayoutInflater from the given context.
     */
    public static LayoutInflater from(Context context) {
        //系统的服务
        LayoutInflater LayoutInflater =
                (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if (LayoutInflater == null) {
            throw new AssertionError("LayoutInflater not found.");
        }
        return LayoutInflater;
    }

     //获取系统服务
    @Override
    public Object getSystemService(String name) {
        return SystemServiceRegistry.getSystemService(this, name);
    }

    // Service registry information.
    // This information is never changed once static initialization has completed.
    private static final HashMap<Class<?>, String> SYSTEM_SERVICE_NAMES =
            new HashMap<Class<?>, String>();
    //在静态代码块中注册LAYOUT_INFLATER_SERVICE的服务.单例
    static {
            registerService(Context.LAYOUT_INFLATER_SERVICE, LayoutInflater.class,
                new CachedServiceFetcher<LayoutInflater>() {
            @Override
            public LayoutInflater createService(ContextImpl ctx) {
                return new PhoneLayoutInflater(ctx.getOuterContext());
            }});
    }

    /**
     * Gets the name of the system-level service that is represented by the specified class.
     */
    public static String getSystemServiceName(Class<?> serviceClass) {
        //从静态的Map获取系统服务.
        return SYSTEM_SERVICE_NAMES.get(serviceClass);
    }

所以LayoutInflater.from(mContext)是一个系统服务.并且是单例的.

1.2 inflate源码分析

    public View inflate(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) {
        //创建Xml解析器
        final XmlResourceParser parser = res.getLayout(resource);
        try {
            //调用这个方法
            return inflate(parser, root, attachToRoot);
        } finally {
            parser.close();
        }
    }

    public View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {
     // Temp is the root view that was found in the xml
     //根据name实例化View
     final View temp = createViewFromTag(root, name, inflaterContext, attrs);
    }

    private View createViewFromTag(View parent, String name, Context context, AttributeSet attrs) {
        return createViewFromTag(parent, name, context, attrs, false);
    }

    View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,
            boolean ignoreThemeAttr) {
 View view;
            //前提看你有没有设置Factory.其实在 AppCompatActivity里面会走这个方法，也就会去替换某些控件
            if (mFactory2 != null) {
                view = mFactory2.onCreateView(parent, name, context, attrs);
            } else if (mFactory != null) {
                view = mFactory.onCreateView(name, context, attrs);
            } else {
                view = null;
            }

            if (view == null) {
                final Object lastContext = mConstructorArgs[0];
                mConstructorArgs[0] = context;
                try {
                    if (-1 == name.indexOf('.')) {
                        //系统的View.在xml中写不带 . 的
                        view = onCreateView(parent, name, attrs);
                    } else {
                        view = createView(name, null, attrs);
                    }
                } finally {
                    mConstructorArgs[0] = lastContext;
                }
            }
}

    protected View onCreateView(View parent, String name, AttributeSet attrs)
            throws ClassNotFoundException {
        return onCreateView(name, attrs);
    }

    protected View onCreateView(String name, AttributeSet attrs)
            throws ClassNotFoundException {
        return createView(name, "android.view.", attrs);
    }
    
    //通过反射创建View
    public final View createView(String name, String prefix, AttributeSet attrs)
            throws ClassNotFoundException, InflateException {
    }