Android獲取LayoutInflater對象的方法總結

在寫Android程序時，有時候會編寫自定義的View，使用Inflater對象來將佈局文件解析成一個View。本文主要目的是總結獲取LayoutInflater對象的方法。

1、若能獲取context對象，可以有以下幾種方法：

LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View child = inflater.inflate(R.layout.child, null);

or

LayoutInflater inflater = LayoutInflater.from(context);
View child = inflater.inflate(R.layout.child, null);

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2、在一個Activity中，可以有以下方法：

View child = getLayoutInflater().inflate(R.layout.child, item, false);

or

View view; 
LayoutInflater inflater = (LayoutInflater)   getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
view = inflater.inflate(R.layout.mylayout, null);

方法1和方法2其實都是對context().getSystemService()的使用

3、使用View的靜態方法：

View view=View.inflate(context, R.layout.child, null)

inflate實現源碼如下：

    /**
     * Inflate a view from an XML resource.  This convenience method wraps the {@link
     * LayoutInflater} class, which provides a full range of options for view inflation.
     *
     * @param context The Context object for your activity or application.
     * @param resource The resource ID to inflate
     * @param root A view group that will be the parent.  Used to properly inflate the
     * layout_* parameters.
     * @see LayoutInflater
     */
    public static View inflate(Context context, int resource, ViewGroup root) {
        LayoutInflater factory = LayoutInflater.from(context);
        return factory.inflate(resource, root);
    }

LayoutInflater.from(context)實際上是對方法1的包裝，可參考以下源碼：

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