Android层面的Fragments与ActionBar的结合< 13、有没有可行的办法？

Question

我想根据我的要求使用尽可能低的 Android 版本编写我的项目，即 11。

但我需要 Fragment.attach 和 ActionBars。

由于级别 11 不包括 Fragment.attach 我导入了 v4 的支持包。

但现在的问题是，ActionTab 的 TabListerner 不使用 v4 Fragment，而是使用 level 11 Fragment。选角不行。

我真的需要切换到13级吗？还是有一个可行的解决方案可以在11级中实现这一切。

代码如下：

import android.app.ActionBar;
import android.app.Activity;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.Fragment;
import android.app.ActionBar.Tab;
import android.app.ActionBar.TabListener;

import android.os.Bundle;
import android.support.v4.app.Fragment;

public class TestActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    }

    public static class TabListener<T extends android.support.v4.app.Fragment> /* to make sure it take the Fragment from the support package! */
    implements ActionBar.TabListener {
    private Fragment mFragment;
    private final Activity mActivity;
    private final String mTag;
    private final Class<T> mClass;

    /**
     * Constructor used each time a new tab is created.
     * 
     * @param activity
     *            The host Activity, used to instantiate the fragment
     * @param tag
     *            The identifier tag for the fragment
     * @param clz
     *            The fragment's Class, used to instantiate the fragment
     */
    public TabListener(Activity activity, String tag, Class<T> clz) {
        mActivity = activity;
        mTag = tag;
        mClass = clz;
    }

    /* The following are each of the ActionBar.TabListener callbacks */

    public void onTabSelected(Tab tab,
        android.support.v4.app.FragmentTransaction ft) {
        // Check if the fragment is already initialized
        if (mFragment == null) {
        // If not, instantiate and add it to the activity
        mFragment = Fragment.instantiate(mActivity, mClass.getName());
        ft.add(android.R.id.content, mFragment, mTag);
        } else {
        // If it exists, simply attach it in order to show it
        ft.attach(mFragment);
        }
    }

    /* these are NOT the implementation of the TabListener above, since the use the
     * 
     * the  FragmentTransactionof the support package and not of level 11
     * 
     */

    public void onTabUnselected(Tab tab,
        android.support.v4.app.FragmentTransaction ft) {
        if (mFragment != null) {
        // Detach the fragment, because another one is being attached
        ft.detach(mFragment);
        }
    }

    public void onTabReselected(Tab tab,
        android.support.v4.app.FragmentTransaction ft) {
        // User selected the already selected tab. Usually do nothing.
    }

    /* these are added since they belong to the above definition of TabListener 
     * 
     * unfortunately the use the FragmentTransaction of level 11, not the one of the support package!
     * 
     */
    @Override
    public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {

    }

    @Override
    public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {
    }

    @Override
    public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {

    }

    }
}

Answer 1

我在 Api Ver 8.0 上使用 ActionBarCompat 和 Fragments ，与您的代码的唯一区别是我使用 ft.replace 而不是 ft.add 以及 xml 上的 ViewPager 来显示片段，到目前为止它运行正常..

import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBar.Tab;

public final class TabListener<T extends Fragment> implements ActionBar.TabListener {
    private Fragment mFragment;
    private final Activity mActivity;
    private final String mTag;
    private final Class<T> mClass;

    /** Constructor used each time a new tab is created.
      * @param activity  The host Activity, used to instantiate the fragment
      * @param tag  The identifier tag for the fragment
      * @param clz  The fragment's Class, used to instantiate the fragment
      */
    public TabListener(Activity activity, String tag, Class<T> clz) {
        mActivity = activity;
        mTag = tag;
        mClass = clz;
    }

    /* The following are each of the ActionBar.TabListener callbacks */

    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        // Check if the fragment is already initialized
        if (mFragment == null) {
            // If not, instantiate and add it to the activity
            mFragment = Fragment.instantiate(mActivity, mClass.getName());
            ft.replace(R.id.pager, mFragment, mTag);
        } else {
            // If it exists, simply attach it in order to show it
            ft.replace(R.id.pager, mFragment, mTag);
        }
    }

    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        if (mFragment != null) {
            // Detach the fragment, because another one is being attached
            ft.remove(mFragment);
        }
    }

    public void onTabReselected(Tab tab, FragmentTransaction ft) {
        // User selected the already selected tab. Usually do nothing.
    }
}

Answer 2

不确定您是否仍然需要这个，但我们使用 ActionBarSherlock ，听起来它也可以帮助您：

http://actionbarsherlock.com /