在PagerAdapter中预加载片段的WebView

时间:2013-04-29 14:56:16

标签: android android-fragments android-webview

我正在使用FragmentStatePagerAdapterFragmets中列出我的ViewPager。每个片段只包含一个WebView。一切正常,我只想使用PagerAdapter的预加载机制,它预先加载1 Fragment。这是我Fragment的简化代码:

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
{
    View view = inflater.inflate(R.layout.ecard_fragment, container, false);
    webview = (WebView) view;
    webview.loadDataWithBaseURL("", HTML, "text/html", "utf-8", "");
    Toast.makeText(getActivity(), "fragment: " + NAME, Toast.LENGTH_SHORT).show();
    return view;
}

我确定,下一个Fragment已预生成,因为Toast已提前显示。但WebView稍后会加载 - 就在关注Fragment之后。如何强制WebView加载?

3 个答案:

答案 0 :(得分:2)

在OnCreate()方法中创建您的webview,然后在OnCreateView()方法中对该webview进行充气。

稍后加载WebView因为onCreateView() - 只有在片段需要将UI加载到用户时才调用方法。

另一方面,OnCreate()在OnCreateView()之前被调用,并且可以实例化片段的基本元素

答案 1 :(得分:0)

我已经编写了简单的演示项目,对我而言,它可以很好地生成邻居视图。这是我的代码:

public class DrawActivity extends FragmentActivity {

@Override
protected void onCreate(Bundle arg0) {
    setContentView(R.layout.pager);
    ((ViewPager) findViewById(R.id.pager)).setAdapter(new ScreenSlidePagerAdapter(getSupportFragmentManager()));
    super.onCreate(arg0);
}

private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {

    public ScreenSlidePagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        return new WebViewFragment(position);
    }

    @Override
    public int getCount() {
        return 3;
    }
}

@SuppressLint("ValidFragment")
private class WebViewFragment extends Fragment {

    private WebView mWebView;
    private int pos;

    public WebViewFragment(int pos) {
        this.pos = pos;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        mWebView = new WebView(getApplicationContext());
        mWebView.loadDataWithBaseURL("", "<h1> ----------------TEST----------------- " + pos + "</h1>", "text/html", "utf-8", "");
        Toast.makeText(getActivity(), "fragment: " + this.toString(), Toast.LENGTH_SHORT).show();
        return mWebView;
    }

}
}

和xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

结果:

enter image description here

答案 2 :(得分:0)

我遇到了同样的问题并通过禁用WebView的硬件加速来修复它:

webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

通过WebViews in ViewPager are not loaded/rendered until page is shown