FragmentHelper

 package com.icitymobile.anda.util;

 import java.lang.ref.SoftReference;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;

 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentTransaction;

 import com.hualong.framework.log.Logger;

 /**
  * Fragment帮助类
  */
 public class FragmentHelper {

     public static final String TAG = "FragmentHelper";

     private static final String STATE_IDS = "fragment_ids";
     private static final String STATE_CURRENT_FRAGMENT_ID = "current_fragment_id";
     private static final String STATE_LAST_FRAGMENT = "last_fragment";

     private Context mContext;
     private FragmentManager mManager;
     private int mContainerId;

     private Map<String, SoftReference<Fragment>> mFragments = new HashMap<String, SoftReference<Fragment>>();
     private String mCurrentFragmentId = null;
     private Fragment mLastFragment;

     public FragmentHelper(Context context, FragmentManager manager, int containerId) {
         mContext = context;
         mManager = manager;
         mContainerId = containerId;
     }

     public Fragment getFragment(String fragmentId) {
         Fragment fragment = null;
         SoftReference<Fragment> reference = mFragments.get(fragmentId);
         if (reference != null) {
             fragment = reference.get();
         }
         return fragment;
     }

     public String getCurrentFragmentId() {
         return mCurrentFragmentId;
     }

     public Fragment getCurrentFragment() {
         return getFragment(getCurrentFragmentId());
     }

     public void switchFragment(String id, Intent intent) {
         switchFragment(id, intent, -);
     }

     public void switchFragment(String id, Intent intent, int transition) {
         if (intent == null) {
             return;
         }
         Fragment newFragment = getFragment(id);
         if (mLastFragment == null || mLastFragment != newFragment) {
             FragmentTransaction ft = mManager.beginTransaction();
             if (mLastFragment != null) {
                 ft.hide(mLastFragment);
             }
             if (newFragment == null) {
                 Logger.i(TAG, TAG + ": Instantiate a new fragment " + id);
                 String fname = intent.getComponent().getClassName();
                 Bundle args = intent.getExtras();
                 newFragment = Fragment.instantiate(mContext, fname);
                 if (args != null) {
                     newFragment.setArguments(args);
                 }
                 mFragments.put(id, new SoftReference<Fragment>(newFragment));
                 ft.add(mContainerId, newFragment, id);
             } else {
                 Logger.i(TAG, TAG + ": Load an old fragment " + id);
                 ft.show(newFragment);
             }
             if (transition != -) {
                 ft.setTransition(transition);
             }
             mLastFragment = newFragment;
             mCurrentFragmentId = id;
             ft.commit();
 //            mManager.executePendingTransactions();
         }
     }

     /**
      * 在Bundle中保存状态
      *
      * @param bundle
      */
     public void saveInBundle(Bundle bundle) {
         if (bundle == null) {
             return;
         }
         Logger.i(TAG, TAG + ": saving in bundle");
         ArrayList<String> idList = new ArrayList<String>(mFragments.keySet());
         bundle.putStringArrayList(STATE_IDS, idList);

         Iterator<Entry<String, SoftReference<Fragment>>> iter = mFragments.entrySet().iterator();
         Entry<String, SoftReference<Fragment>> entry;
         SoftReference<Fragment> reference;
         Fragment fragment;
         while (iter.hasNext()) {
             entry = iter.next();
             reference = entry.getValue();
             if (reference != null) {
                 fragment = reference.get();
                 if (fragment != null) {
                     mManager.putFragment(bundle, entry.getKey(), fragment);
                 }
             }
         }

         if (mCurrentFragmentId != null) {
             bundle.putString(STATE_CURRENT_FRAGMENT_ID, mCurrentFragmentId);
         }

         if (mLastFragment != null) {
             mManager.putFragment(bundle, STATE_LAST_FRAGMENT, mLastFragment);
         }
     }

     /**
      * 在Bundle中保存状态，只保存当前的fragment
      *
      * @param bundle
      */
     public void saveStateSimple(Bundle bundle) {
         if (bundle == null) {
             return;
         }
         Logger.i(TAG, TAG + ": saving in bundle simple");

         if (mCurrentFragmentId != null) {
             bundle.putString(STATE_CURRENT_FRAGMENT_ID, mCurrentFragmentId);

             ArrayList<String> idList = new ArrayList<String>();
             idList.add(mCurrentFragmentId);
             bundle.putStringArrayList(STATE_IDS, idList);

             Fragment currentFragment = getCurrentFragment();
             if (currentFragment != null) {
                 mManager.putFragment(bundle, mCurrentFragmentId, currentFragment);
             }
         }

         if (mLastFragment != null) {
             mManager.putFragment(bundle, STATE_LAST_FRAGMENT, mLastFragment);
         }
     }

     /**
      * 从Bundle中恢复状态
      *
      * @param bundle
      */
     public void restoreFromBundle(Bundle bundle) {
         if (bundle == null) {
             return;
         }
         Logger.i(TAG, TAG + ": restoring from bundle");
         ArrayList<String> idList = bundle.getStringArrayList(STATE_IDS);
         if (idList != null) {
             Fragment fragment;
             for (String id : idList) {
                 fragment = mManager.getFragment(bundle, id);
                 if (fragment != null) {
                     mFragments.put(id, new SoftReference<Fragment>(fragment));
                 }
             }
         }

         String currentId = bundle.getString(STATE_CURRENT_FRAGMENT_ID);
         if (currentId != null) {
             mCurrentFragmentId = currentId;
         }

         Fragment lastFragment = mManager.getFragment(bundle, STATE_LAST_FRAGMENT);
         if (lastFragment != null) {
             mLastFragment = lastFragment;
         }
     }
 }