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);