# 5.2.5 Fragment實例精講——新聞(購物)類App列表Fragment的簡單實現 ## 本節引言： > 相信大家對點擊列表，然后進入詳情這種App并不陌生吧，在購物類App和新聞類App中最為常見： 下面我們簡單來講一下流程邏輯！ ## 1.邏輯流程講解： 剛好公司測試妹子的測試機上裝了楚楚街9塊9的APP，呵呵，直接就照這個來研究吧：  嘿嘿，市面上很多APP都是這種樣子的，而這個可以用我們學到的Fragment來實現： 可能gif動畫看不清，筆者用界面原型工具畫個大概吧：  大概就這樣，中間區域是一個布局容器，一般是FrameLayout，然后我們將一個Fragment replace 到這個容器中或者add也行，而這個Fragment中有一個listview，當我們點擊這個ListView中的一項， 中間容器中的Fragment就會被replace成對應詳細信息的Fragment所替代，如果我們只是replace的話， 就不會保存第一個Fragment的狀態，用戶又得從頭開始瀏覽，這肯定是很不方便的，這里我們可以 通過Fragment棧的addtobackStack和popbackstack來解決這個問題！當replace的同時，我們將被替換 的Fragment添加到stack中，當用戶點擊回退按鈕時，調用popbackstack彈出棧，具體實現見下述代碼 示例！ ## 2.代碼示例：簡單新聞類APP列表和內容切換的實現 **運行效果圖**：  **實現代碼**： **Step 1**:先把兩個Fragment以及Activity的布局實現了 **fg_newlist.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:background="@color/white" android:orientation="horizontal"> <ListView android:id="@+id/list_news" android:layout_width="match_parent" android:layout_height="match_parent" /> </LinearLayout> ``` **fg_context.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"> <TextView android:id="@+id/txt_content" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:textColor="@color/blue" android:textSize="20sp" /> </LinearLayout> ``` **activity_main.xml**: ``` <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <TextView android:id="@+id/txt_title" android:layout_width="match_parent" android:layout_height="56dp" android:background="@color/blue" android:textColor="@color/white" android:text="新聞列表" android:textSize="20sp" android:textStyle="bold" android:gravity="center"/> <FrameLayout android:id="@+id/fl_content" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/txt_title"/> </RelativeLayout> ``` **Step 2**:實現我們的業務Bean類和自定義BaseAdapter類： **Data.java:** ``` /** * Created by Jay on 2015/9/6 0006. */ public class Data { private String new_title; private String new_content; public Data(){} public Data(String new_title, String new_content) { this.new_title = new_title; this.new_content = new_content; } public String getNew_title() { return new_title; } public String getNew_content() { return new_content; } public void setNew_title(String new_title) { this.new_title = new_title; } public void setNew_content(String new_content) { this.new_content = new_content; } } ``` **MyAdapter.java**: ``` /** * Created by Jay on 2015/9/6 0006. */ public class MyAdapter extends BaseAdapter{ private List<Data> mData; private Context mContext; public MyAdapter(List<Data> mData, Context mContext) { this.mData = mData; this.mContext = mContext; } @Override public int getCount() { return mData.size(); } @Override public Object getItem(int position) { return null; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder; if(convertView == null){ convertView = LayoutInflater.from(mContext).inflate(R.layout.list_item,parent,false); viewHolder = new ViewHolder(); viewHolder.txt_item_title = (TextView) convertView.findViewById(R.id.txt_item_title); convertView.setTag(viewHolder); }else{ viewHolder = (ViewHolder) convertView.getTag(); } viewHolder.txt_item_title.setText(mData.get(position).getNew_title()); return convertView; } private class ViewHolder{ TextView txt_item_title; } } ``` **Step 3**:MainActivity的實現 **MainActivity.java**: ``` public class MainActivity extends AppCompatActivity { private TextView txt_title; private FrameLayout fl_content; private Context mContext; private ArrayList<Data> datas = null; private FragmentManager fManager = null; private long exitTime = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mContext = MainActivity.this; fManager = getFragmentManager(); bindViews(); datas = new ArrayList<Data>(); for (int i = 1; i <= 20; i++) { Data data = new Data("新聞標題" + i, i + "~新聞內容~~~~~~~~"); datas.add(data); } NewListFragment nlFragment = new NewListFragment(fManager, datas); FragmentTransaction ft = fManager.beginTransaction(); ft.replace(R.id.fl_content, nlFragment); ft.commit(); } private void bindViews() { txt_title = (TextView) findViewById(R.id.txt_title); fl_content = (FrameLayout) findViewById(R.id.fl_content); } //點擊回退鍵的處理：判斷Fragment棧中是否有Fragment //沒，雙擊退出程序，否則像是Toast提示 //有，popbackstack彈出棧 @Override public void onBackPressed() { if (fManager.getBackStackEntryCount() == 0) { if ((System.currentTimeMillis() - exitTime) > 2000) { Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show(); exitTime = System.currentTimeMillis(); } else { super.onBackPressed(); } } else { fManager.popBackStack(); txt_title.setText("新聞列表"); } } } ``` **Step 4**:列表Fragment的實現： **NewListFragment.java**： ``` package com.jay.fragmentdemo4; import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.ListView; import android.widget.TextView; import java.util.ArrayList; /** * Created by Jay on 2015/9/6 0006. */ public class NewListFragment extends Fragment implements AdapterView.OnItemClickListener { private FragmentManager fManager; private ArrayList<Data> datas; private ListView list_news; public NewListFragment(FragmentManager fManager, ArrayList<Data> datas) { this.fManager = fManager; this.datas = datas; } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fg_newlist, container, false); list_news = (ListView) view.findViewById(R.id.list_news); MyAdapter myAdapter = new MyAdapter(datas, getActivity()); list_news.setAdapter(myAdapter); list_news.setOnItemClickListener(this); return view; } @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { FragmentTransaction fTransaction = fManager.beginTransaction(); NewContentFragment ncFragment = new NewContentFragment(); Bundle bd = new Bundle(); bd.putString("content", datas.get(position).getNew_content()); ncFragment.setArguments(bd); //獲取Activity的控件 TextView txt_title = (TextView) getActivity().findViewById(R.id.txt_title); txt_title.setText(datas.get(position).getNew_content()); //加上Fragment替換動畫 fTransaction.setCustomAnimations(R.anim.fragment_slide_left_enter, R.anim.fragment_slide_left_exit); fTransaction.replace(R.id.fl_content, ncFragment); //調用addToBackStack將Fragment添加到棧中 fTransaction.addToBackStack(null); fTransaction.commit(); } } ``` **Step 5**:內容Fragment的實現： **NewContentFragment.java**: ``` /** * Created by Jay on 2015/9/6 0006. */ public class NewContentFragment extends Fragment { NewContentFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fg_content, container, false); TextView txt_content = (TextView) view.findViewById(R.id.txt_content); //getArgument獲取傳遞過來的Bundle對象 txt_content.setText(getArguments().getString("content")); return view; } } ``` 代碼很簡單，就不慢慢解釋了~ ## 3.代碼下載 **FragmentDemo5.zip**：[下載 FragmentDemo5.zip](/try/download/FragmentDemo5.zip) ## 本節小結： > 因為時間的關系，并沒有詳細的去做過多的講解，示例代碼也很簡單，方便各位初學者理解！ 如果要用到實際項目中還需要對此進行一番修改~！好的，本節就到這里，謝謝~