webview中back键拦截,弹出窗口进行确认

1.在android中拦截实现

webView.loadUrl("file:///android_asset/index.html");    //webview界面

webView.setOnKeyListener(new View.OnKeyListener()
{
    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);   //创建弹出窗口

    @Override
    public boolean onKey(View view, int i, KeyEvent keyEvent)
    {
        Log.e("onKey", keyEvent.toString());
        if(KeyEvent.KEYCODE_BACK == i && 0 == keyEvent.getRepeatCount() && KeyEvent.ACTION_DOWN == keyEvent.getAction())
        {
            if (webView != null && webView.canGoBack())
            {
                        webView.goBack();
            }
            else
            {
                builder.setTitle("是否确定退出");
                builder.setPositiveButton("确定退出", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i)
                    {
                        //点击确定退出的处理方式
                        finish();
                    }
                });
                builder.setNegativeButton("取消退出", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i)
                    {
                        //点击取消键的处理方式
                    }
                });
                builder.setOnKeyListener(new DialogInterface.OnKeyListener()
                {
                    @Override
                    public boolean onKey(DialogInterface dialogInterface, int i, KeyEvent keyEvent)
                    {
                        //在弹出窗口下，再次点击返回键的处理方式。
                        if(KeyEvent.KEYCODE_BACK == i)
                            return true;    //使返回键无效
                        return false;
                    }
                });
                builder.create().show();    //弹出窗口
                return true;    //返回键拦截
            }
        }
        return false;   //其他键，照常响应。
    }
});