# 5.2.5 Fragment实例精讲——新闻(购物)类App列表Fragment的简单实现 ## 本节引言： > 相信大家对点击列表，然后进入详情这种App并不陌生吧，在购物类App和新闻类App中最为常见： 下面我们简单来讲一下流程逻辑！ ## 1.逻辑流程讲解： 刚好公司测试妹子的测试机上装了楚楚街9块9的APP，呵呵，直接就照这个来研究吧：  嘿嘿，市面上很多APP都是这种样子的，而这个可以用我们学到的Fragment来实现： 可能gif动画看不清，笔者用界面原型工具画个大概吧：  大概就这样，中间区域是一个布局容器，一般是FrameLayout，然后我们将一个Fragment replace 到这个容器中或者add也行，而这个Fragment中有一个listview，当我们点击这个ListView中的一项， 中间容器中的Fragment就会被replace成对应详细信息的Fragment所替代，如果我们只是replace的话， 就不会保存第一个Fragment的状态，用户又得从头开始浏览，这肯定是很不方便的，这里我们可以 通过Fragment栈的addtobackStack和popbackstack来解决这个问题！当replace的同时，我们将被替换 的Fragment添加到stack中，当用户点击回退按钮时，调用popbackstack弹出栈，具体实现见下述代码 示例！ ## 2.代码示例：简单新闻类APP列表和内容切换的实现 **运行效果图**：  **实现代码**： **Step 1**:先把两个Fragment以及Activity的布局实现了 **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="新闻列表" 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**:实现我们的业务Bean类和自定义BaseAdapter类： **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的实现 **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("新闻标题" + i, i + "~新闻内容~~~~~~~~"); 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); } //点击回退键的处理：判断Fragment栈中是否有Fragment //没，双击退出程序，否则像是Toast提示 //有，popbackstack弹出栈 @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("新闻列表"); } } } ``` **Step 4**:列表Fragment的实现： **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); //获取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替换动画 fTransaction.setCustomAnimations(R.anim.fragment_slide_left_enter, R.anim.fragment_slide_left_exit); fTransaction.replace(R.id.fl_content, ncFragment); //调用addToBackStack将Fragment添加到栈中 fTransaction.addToBackStack(null); fTransaction.commit(); } } ``` **Step 5**:内容Fragment的实现： **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获取传递过来的Bundle对象 txt_content.setText(getArguments().getString("content")); return view; } } ``` 代码很简单，就不慢慢解释了~ ## 3.代码下载 **FragmentDemo5.zip**：[下载 FragmentDemo5.zip](/try/download/FragmentDemo5.zip) ## 本节小结： > 因为时间的关系，并没有详细的去做过多的讲解，示例代码也很简单，方便各位初学者理解！ 如果要用到实际项目中还需要对此进行一番修改~！好的，本节就到这里，谢谢~