在主Android Activity中加载Fragment的一般简易方法 ，来模拟一个微信界面。

在Fragment的生命周期中，需要重点关注onCreate、onCreateView、onViewCreated。Activity与Fragment生命周期在设计模式上大体一致。

 package com.lixu.fragment_test;

 import android.app.Activity;

 import android.app.FragmentManager;
 import android.app.FragmentTransaction;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.Window;
 import android.widget.ImageView;

 public class MainActivity extends Activity implements OnClickListener {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         requestWindowFeature(Window.FEATURE_NO_TITLE);
         setContentView(R.layout.activity_main);
         //设置初始界面为“微信”。
         getweixn();

         ImageView iv1 = (ImageView) findViewById(R.id.iv1);
         ImageView iv2 = (ImageView) findViewById(R.id.iv2);
         ImageView iv3 = (ImageView) findViewById(R.id.iv3);
         ImageView iv4 = (ImageView) findViewById(R.id.iv4);

         iv1.setOnClickListener(this);
         iv2.setOnClickListener(this);
         iv3.setOnClickListener(this);
         iv4.setOnClickListener(this);

     }

     public void getweixn() {
         FragmentManager fm = this.getFragmentManager();
         FragmentTransaction ft = fm.beginTransaction();
         // 将原有的Activity替换成Fragment。也可以添加到原有之上不替换 如：ft.add(R.id.rel, new
         // Fragment()) ;如果添加的多了会比较耗资源。
         ft.replace(R.id.fl, new MyFragment1());
         // 提交
         ft.commit();

     }

     public void gettongxunlu() {
         //设置Fragment管理器
         FragmentManager fm = this.getFragmentManager();
         FragmentTransaction ft = fm.beginTransaction();

         ft.replace(R.id.fl, new MyFragment2());

         ft.commit();

     }

     public void getfaxian() {
         FragmentManager fm = this.getFragmentManager();
         FragmentTransaction ft = fm.beginTransaction();

         ft.replace(R.id.fl, new MyFragment3());

         ft.commit();

     }

     public void getwo() {
         FragmentManager fm = this.getFragmentManager();
         FragmentTransaction ft = fm.beginTransaction();

         ft.replace(R.id.fl, new MyFragment4());

         ft.commit();

     }

     @Override
     public void onClick(View v) {
         switch (v.getId()) {
         case R.id.iv1:
             getweixn();
             break;
         case R.id.iv2:
             gettongxunlu();
             break;
         case R.id.iv3:
             getfaxian();
             break;
         case R.id.iv4:
             getwo();
             break;

         default:
             break;
         }
     }

 }

 package com.lixu.fragment_test;

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

 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;

 class MyFragment1 extends Fragment {

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
     }

     // 创建view   也可以直接在这里面获取view中的控件。
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

         View view = inflater.inflate(R.layout.image, null);

         return view;
     }

     // 创建view完毕  可以直接在onCreateView中获取view中控件。
     @Override
     public void onViewCreated(View view, Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);

         ImageView iv = (ImageView) view.findViewById(R.id.iv);
         iv.setImageResource(R.drawable.weixinjiemian);
     }
 }

 package com.lixu.fragment_test;

 import java.util.ArrayList;
 import java.util.HashMap;

 import android.app.Fragment;
 import android.content.Context;
 import android.graphics.Color;
 import android.os.Bundle;

 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ArrayAdapter;
 import android.widget.ListView;
 import android.widget.TextView;

 class MyFragment2 extends Fragment {
     private static final String TYPE = "type";
     private static final String DATE = "date";
     private static final int GROUP = -1;
     private static final int ITEM = -2;

     private ArrayList<HashMap<String, Object>> item = null;

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

     }

     // 创建view
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

         View view = inflater.inflate(R.layout.list, null);

         return view;
     }

     // 创建view完毕
     @Override
     public void onViewCreated(View view, Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);

         ListView lv = (ListView) view.findViewById(R.id.lv);
         MyAdaper adapter = new MyAdaper(getActivity(), -1);

         item = new ArrayList<HashMap<String, Object>>();

         String[] groups = { "家人", "朋友", "同学", "同事" };
         String[] date = { "张三", "李四", "王五", "狗儿" };
         for (String str : groups) {
             HashMap<String, Object> group_map = new HashMap<String, Object>();

             group_map.put(TYPE, GROUP);
             group_map.put(DATE, str);
             item.add(group_map);
             for (String n : date) {

                 HashMap<String, Object> date_map = new HashMap<String, Object>();

                 date_map.put(TYPE, ITEM);
                 date_map.put(DATE, n);
                 item.add(date_map);

             }

         }
         lv.setAdapter(adapter);
     }

     private class MyAdaper extends ArrayAdapter {
         private LayoutInflater flater = null;
         private Context context;

         public MyAdaper(Context context, int resource) {
             super(context, resource);
             this.context = context;
             flater = LayoutInflater.from(context);
         }

         @Override
         public int getCount() {
             return item.size();
         }

         @Override
         public int getItemViewType(int position) {
             HashMap<String, Object> map = item.get(position);
             return (Integer) map.get(TYPE);
         }

         @Override
         public int getViewTypeCount() {

             return 2;
         }

         @Override
         public View getView(int position, View convertView, ViewGroup parent) {
             int type = getItemViewType(position);
             // 根据不同的view type加载不同的布局文件。
             switch (type) {
             case GROUP:

                 convertView = flater.inflate(android.R.layout.simple_list_item_1, null);
                 TextView tv1 = (TextView) convertView.findViewById(android.R.id.text1);
                 tv1.setText(item.get(position).get(DATE) + "");
                 tv1.setBackgroundColor(Color.RED);
                 tv1.setTextSize(20);

                 break;
             case ITEM:
                 convertView = flater.inflate(android.R.layout.simple_list_item_1, null);
                 TextView tv2 = (TextView) convertView.findViewById(android.R.id.text1);
                 tv2.setText(item.get(position).get(DATE) + "");

                 break;

             default:
                 break;
             }

             return convertView;
         }

     }
 }

 package com.lixu.fragment_test;

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

 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;

 class MyFragment3 extends Fragment {

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
     }

     // 创建view
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

         View view = inflater.inflate(R.layout.image, null);

         return view;
     }

     // 创建view完毕
     @Override
     public void onViewCreated(View view, Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);

         ImageView iv = (ImageView) view.findViewById(R.id.iv);
         iv.setImageResource(R.drawable.faxianjiemian);
     }
 }

 package com.lixu.fragment_test;

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

 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;

 class MyFragment4 extends Fragment {

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
     }

     // 创建view
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

         View view = inflater.inflate(R.layout.image, null);

         return view;
     }

     // 创建view完毕
     @Override
     public void onViewCreated(View view, Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);

         ImageView iv = (ImageView) view.findViewById(R.id.iv);
         iv.setImageResource(R.drawable.wojiemian);
     }
 }

xml文件：

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/LinearLayout1"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical"
     tools:context="com.lixu.fragment_test.MainActivity" >

     <FrameLayout
         android:id="@+id/fl"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_weight="1" >
     </FrameLayout>

     <LinearLayout
         android:id="@+id/linearlayout"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:orientation="horizontal" >

         <ImageView
             android:id="@+id/iv1"
             android:layout_width="90dp"
             android:layout_height="60dp"
             android:layout_weight="1"
             android:background="@drawable/weixin" />

         <ImageView
             android:id="@+id/iv2"
             android:layout_width="90dp"
             android:layout_height="60dp"
             android:layout_weight="1"
             android:background="@drawable/tongxunlu" />

         <ImageView
             android:id="@+id/iv3"
             android:layout_width="90dp"
             android:layout_height="60dp"
             android:layout_weight="1"
             android:background="@drawable/faxian" />

         <ImageView
             android:id="@+id/iv4"
             android:layout_width="90dp"
             android:layout_height="60dp"
             android:layout_weight="1"
             android:background="@drawable/wo" />
     </LinearLayout>

 </LinearLayout>

 <?xml version="1.0" encoding="utf-8"?>
 <ImageView xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/iv"
     android:layout_width="match_parent"
     android:layout_height="match_parent" >

 </ImageView>

 <?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" >

     <ListView
         android:id="@+id/lv"
         android:layout_width="match_parent"
         android:layout_height="match_parent" >
     </ListView>

 </LinearLayout>

运行效果图，演示为主，效果为辅，图片有点不真实，哈哈。