webview子类中无法调起输入键盘的问题

看一下webview自己的构造方法：

    /**
     * Construct a new WebView with a Context object.
     * @param context A Context object used to access application assets.
     */
    public WebView(Context context) {
        this(context, null);
    }

    /**
     * Construct a new WebView with layout parameters.
     * @param context A Context object used to access application assets.
     * @param attrs An AttributeSet passed to our parent.
     */
    public WebView(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.webViewStyle);
    }

    /**
     * Construct a new WebView with layout parameters and a default style.
     * @param context A Context object used to access application assets.
     * @param attrs An AttributeSet passed to our parent.
     * @param defStyle The default style resource ID.
     */
    public WebView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

上面红色标记的地方就是关键所在，平时当我们自定义view的时候，可能会习惯把三个构造这样写：

    public XxxView(Context context) {
        this(context, null);
    }

    public XxxView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public XxxView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    private void init(){
        ......
    }